RECALLS 2 Flashcards

Question

Which of the following is not a feature of normal cerebrospinal fluid? It has a pressure of between 10 and 15 mmHg. It usually contains a small amount of glucose. It may normally contain up to 5 red blood cells per mm3. It may normally contain up to 3 white blood cells per mm3. None of the above

Answer 1

Let me think about this step by step: 1. CSF Pressure: - Normal CSF pressure is 10-15 mmHg when measured by lumbar puncture - This is a correct feature of normal CSF 2. Glucose content: - Normal CSF does contain glucose - The level is typically about 2/3 of blood glucose - This is a correct feature 3. Red blood cells (RBCs): - Normal CSF should not contain any RBCs - The presence of RBCs indicates either a traumatic tap or pathology - Up to 5 RBCs per mm3 is NOT a normal feature 4. White blood cells (WBCs): - Normal CSF can contain 0-5 WBCs per mm3 - 3 WBCs per mm3 falls within this range - This is a correct feature Therefore, the statement that "It may normally contain up to 5 red blood cells per mm3" is NOT a feature of normal CSF. This is the answer. The presence of any RBCs in CSF is abnormal and should prompt investigation for: - Traumatic tap during collection - Subarachnoid hemorrhage - Other pathological conditions

Answer 2

The Cushing triad is a clinical syndrome associated with increased intracranial pressure (ICP). It consists of three main components: hypertension, bradycardia, and irregular respiration. The bradycardia in Cushing triad is primarily due to the body's response to increased ICP, which involves the autonomic nervous system. Here’s the mechanism: 1. **Increased Intracranial Pressure (ICP):** As ICP rises, it compresses the brainstem, including the medulla oblongata, which houses the cardiovascular and respiratory centers. 2. **Cushing Reflex:** The body responds to the decreased cerebral perfusion caused by the increased ICP. The initial response is systemic vasoconstriction to increase blood pressure (hypertension) to ensure adequate blood flow to the brain. 3. **Baroreceptor Response:** The increased blood pressure is detected by baroreceptors located in the carotid sinus and aortic arch. These baroreceptors send signals to the medulla oblongata to decrease heart rate (bradycardia) as a compensatory mechanism to reduce the blood pressure. 4. **Parasympathetic Activation:** The medulla oblongata increases parasympathetic (vagal) outflow to the heart, leading to bradycardia. Given this mechanism, the correct answer is: **C. Decreased activity from carotid sinus** Explanation: The baroreceptors in the carotid sinus detect the elevated blood pressure and decrease their firing rate, which leads to increased parasympathetic activity and subsequent bradycardia. This is a reflex response to the hypertension caused by the Cushing reflex. The other options are incorrect because: - **A. Increased activity from carotid body:** The carotid body responds to changes in oxygen, carbon dioxide, and pH levels, not directly to blood pressure changes. - **B. Increased activity from aortic body:** Similar to the carotid body, the aortic body responds to chemical changes in the blood, not directly to blood pressure. - **D. Decreased activity from cardiopulmonary receptors:** These receptors are involved in regulating blood volume and pressure but are not the primary mechanism in the Cushing triad. - **E. Increased activity from aortic sinus:** The aortic sinus contains baroreceptors that respond to increased blood pressure by decreasing heart rate, but the primary site for this reflex in the context of Cushing triad is the carotid sinus.

Answer 3

The pharyngeal diverticulum you are referring to is most likely a **Zenker's diverticulum**, which is a type of esophageal diverticulum. This condition occurs due to a weakness in the pharyngeal musculature, specifically at **Killian's dehiscence**, which is an anatomical area of potential weakness in the posterior pharyngeal wall. ### Site of the Diverticulum: - **Killian's dehiscence** is located **between the inferior constrictor muscle and the cricopharyngeus muscle** (which is the upper esophageal sphincter). - This area is **above the inferior constrictor muscle** but **below the middle constrictor muscle**. ### Correct Answer: **D. Above the inferior constrictor** ### Explanation: - The diverticulum forms in the posterior pharyngeal wall, specifically in the area of Killian's dehiscence, which is located **above the inferior constrictor muscle** but **below the middle constrictor muscle**. - This is the most common site for a Zenker's diverticulum to develop. ### Why Not the Other Options? - **A. Above superior constrictor:** This is not the site of Zenker's diverticulum. - **B. Between superior and middle constrictor:** This is not the site of weakness where Zenker's diverticulum typically forms. - **C. Between medial and inferior constrictor:** This is not anatomically correct. - **E. Through inferior constrictor muscles:** The diverticulum does not form through the inferior constrictor muscles but rather above them at Killian's dehiscence. Thus, the correct answer is **D. Above the inferior constrictor**.

Answer 4

The correct answer is: C. Passes behind the pulmonary trunk. Explanation: • The left coronary artery (LCA) arises from the left posterior aortic sinus, also known as the left coronary sinus oai_citation:0‡Anatomy Questions for the MRCS.pdf. • It passes forward from its origin, behind the pulmonary trunk, and then courses anterior to the left auricle oai_citation:1‡Anatomy Questions for the MRCS.pdf. • It then bifurcates into the left anterior descending (LAD) artery and the circumflex artery oai_citation:2‡Anatomy Questions for the MRCS.pdf. Why Other Options Are Incorrect: • A. Arises from posterior aortic sinus – Incorrect, as it arises from the left posterior aortic sinus, not the general “posterior aortic sinus” oai_citation:3‡Anatomy Questions for the MRCS.pdf. • B. Arises from below anterior aortic valve – Incorrect, as it arises from the left posterior aortic sinus, not below the valve oai_citation:4‡Anatomy Questions for the MRCS.pdf. • D. Situated in posterior interventricular groove – Incorrect, as the posterior interventricular groove contains the posterior interventricular artery, which is usually a branch of the right coronary artery or the circumflex artery in left-dominant hearts oai_citation:5‡Anatomy Questions for the MRCS.pdf. • E. Arises from anterior ascending aorta – Incorrect, as it arises from the left posterior aortic sinus, which is not directly from the ascending aorta oai_citation:6‡Anatomy Questions for the MRCS.pdf. Thus, the left coronary artery passes behind the pulmonary trunk before dividing into its branches.

Answer 5

The patient in question is a 53-year-old man who has undergone emergency abdominal aortic aneurysm repair and is now in the intensive care unit. He has developed abdominal pain and diarrhea and is profoundly unwell, though his abdomen does not show signs of peritonism. This clinical scenario is concerning for **mesenteric ischemia**, a condition where blood flow to the intestines is compromised, leading to tissue hypoxia, acidosis, and elevated lactate levels. Let’s analyze the arterial blood gas (ABG) options: 1. **pH 7.45, pO2 10.1, pCO2 3.2, Base excess 0, Lactate 0** - This ABG shows a slightly alkalotic pH, low pCO2 (respiratory alkalosis), and normal lactate. This is unlikely in a profoundly unwell patient with suspected mesenteric ischemia. 2. **pH 7.35, pO2 8.0, pCO2 5.2, Base excess 2, Lactate 1** - This ABG is within normal limits, with no acidosis or elevated lactate. This is inconsistent with the clinical picture of mesenteric ischemia. 3. **pH 7.20, pO2 9.0, pCO2 3.5, Base excess -10, Lactate 8** - This ABG shows a significant **metabolic acidosis** (low pH, low bicarbonate/base excess, and elevated lactate). The elevated lactate (8 mmol/L) is a key finding, as it indicates tissue hypoxia and anaerobic metabolism, which is consistent with mesenteric ischemia. The low pCO2 suggests a compensatory respiratory alkalosis. 4. **pH 7.29, pO2 8.9, pCO2 5.9, Base excess -4, Lactate 3** - This ABG shows a mild metabolic acidosis with a moderately elevated lactate. While this could be seen in early or less severe mesenteric ischemia, it is less likely in a profoundly unwell patient. 5. **pH 7.30, pO2 9.2, pCO2 4.8, Base excess -2, Lactate 1** - This ABG shows a mild acidosis with a normal lactate. This is not consistent with the severe clinical picture described. ### Conclusion: The most likely ABG in this patient is: **pH 7.20, pO2 9.0, pCO2 3.5, Base excess -10, Lactate 8** This reflects a severe metabolic acidosis with elevated lactate, which is characteristic of mesenteric ischemia.

Answer 6

Correct Answer: A) IV Pamidronate Hypercalcemia (corrected calcium >3.0 mmol/L) is a medical emergency and requires urgent treatment to prevent complications such as nephrocalcinosis, arrhythmias, and neurological deterioration. Stepwise Management of Severe Hypercalcemia (>3.0 mmol/L): 1. Aggressive IV Fluid Resuscitation – 0.9% Normal Saline to correct dehydration and enhance renal calcium excretion. 2. IV Bisphosphonates (Pamidronate or Zoledronate) – Pamidronate is the first-line choice as it inhibits osteoclastic bone resorption, lowering calcium levels within 2–4 days. 3. Calcitonin (if needed for rapid lowering) – Acts quicker but is short-lived. 4. Consider Steroids (Dexamethasone) if hypercalcemia is due to granulomatous disease or lymphoma. Why not the other options? • Oral Alendronate (B) – Used for osteoporosis, not for acute hypercalcemia. • Dexamethasone (C) – Can help in some malignancy-related cases but is not the first-line treatment. • Vitamin D (D) – Would worsen hypercalcemia, especially in vitamin D toxicity or sarcoidosis. • Resonium salts (E) – Used for hyperkalemia, not hypercalcemia. Thus, IV Pamidronate is the treatment of choice for severe hypercalcemia in this patient.

Answer 7

Correct Answer: B) Reduction in ionised calcium levels Mechanism: • Hyperventilation causes respiratory alkalosis due to excessive CO₂ exhalation. • This leads to a rise in blood pH, causing increased binding of calcium to albumin. • As a result, ionised (free) calcium levels fall, leading to neuromuscular excitability (tetany, paraesthesia, twitching). • This is why the patient develops circumoral paraesthesia and muscle twitching—classic signs of acute hypocalcaemia due to alkalosis. Why not the other options? • A) Temporal lobe epilepsy – Epilepsy would cause altered consciousness, automatisms, or seizures, not selective paraesthesia/twitching due to hyperventilation. • C) Increase in ionised calcium levels – Hyperventilation leads to reduced ionised calcium, not an increase. • D) Fall in serum PTH levels – PTH regulation takes time and does not cause immediate symptoms like this. • E) Rise in serum PTH levels – PTH increases in chronic hypocalcaemia but does not contribute to the acute symptoms seen here. Thus, hyperventilation-induced respiratory alkalosis leads to a fall in ionised calcium levels, causing neuromuscular excitability, making option B the correct answer.

Answer 8

Correct Answer: A) Formation of IgG antibodies to the TSH receptors on the thyroid gland Pathophysiology of Graves’ Disease: • Graves’ disease is an autoimmune disorder in which the body produces thyroid-stimulating immunoglobulins (TSI). • These are IgG antibodies that bind to and activate the TSH receptors on the thyroid gland, leading to excess thyroid hormone production (hyperthyroidism). • This continuous stimulation leads to thyroid gland enlargement (goitre) and systemic effects of excessive thyroid hormones. Why not the other options? • B) Formation of IgG antibodies to TRH receptors on the anterior pituitary – Graves’ disease does not affect TRH receptors; the pathology is at the level of the thyroid gland. • C) Formation of IgM antibodies to TSH receptors on the thyroid gland – The antibodies in Graves’ disease are IgG, not IgM. • D) Formation of IgA antibodies to TSH receptors on the thyroid gland – IgA is mainly involved in mucosal immunity, not autoimmune thyroid disease. • E) Formation of IgM antibodies to TRH receptors on the anterior pituitary – Again, Graves’ disease does not involve TRH receptors or IgM antibodies. Key Learning Points: • Graves’ disease is caused by IgG autoantibodies against TSH receptors, leading to hyperthyroidism. • Exophthalmos and pretibial myxoedema occur due to antibody-mediated stimulation of fibroblasts in the orbit and skin. • TSH levels are low due to negative feedback from excess T3 and T4. Thus, option A is the correct answer.

Answer 9

Nausea inhibits gastric acid secretion. Explanation: • Histamine: Stimulates gastric acid secretion by binding to H₂ receptors on parietal cells. • Nausea: Generally inhibits gastric acid secretion, likely due to the activation of inhibitory pathways in the brainstem that reduce gastric motility and secretion. • Calcium: Can stimulate acid secretion by increasing gastrin release. • Parasympathetic vagal stimulation: Increases gastric acid secretion via acetylcholine acting on parietal cells. • Gastrin: Strongly stimulates gastric acid secretion by directly acting on parietal cells and indirectly by stimulating histamine release. So, the correct answer is nausea.

Answer 10

In this scenario, the patient is experiencing massive postoperative hemorrhage (1600 mL of fresh blood loss). This will lead to hypovolemic shock, triggering compensatory mechanisms. Let’s analyze the listed parameters: 1. Cardiac output → Decreases • Severe blood loss reduces preload (venous return), leading to a drop in stroke volume and cardiac output. 2. Renin secretion → Increases • The loss of blood volume activates the renin-angiotensin-aldosterone system (RAAS) in an attempt to restore blood pressure. 3. Firing of carotid baroreceptors → Decreases • Baroreceptors (in the carotid sinus) respond to arterial stretch. With hemorrhage-induced hypotension, there is less stretch, leading to reduced firing. 4. Firing of aortic baroreceptors → Decreases • Similar to the carotid baroreceptors, aortic baroreceptors (located in the aortic arch) respond to stretch. Blood loss reduces arterial pressure, leading to decreased firing. 5. Blood pressure → Decreases • Massive blood loss reduces circulating volume, causing a drop in blood pressure. Answer: Renin secretion is unlikely to decrease—it actually increases in response to hypovolemia.

Answer 11

The correct answer is heparin. Explanation: Hyperkalemia (elevated potassium levels) can occur due to various mechanisms, including reduced renal excretion, increased potassium release from cells, or altered hormonal regulation. Let’s analyze each drug: 1. Heparin → Can cause hyperkalemia • Heparin inhibits aldosterone secretion, leading to reduced potassium excretion by the kidneys, which can result in hyperkalemia. 2. Ciprofloxacin → Does not typically cause hyperkalemia • Fluoroquinolones like ciprofloxacin are not strongly associated with potassium disturbances. 3. Salbutamol → Causes hypokalemia • Salbutamol (a β₂-agonist) stimulates Na⁺/K⁺ ATPase, driving potassium into cells and reducing serum potassium. 4. Levothyroxine → No significant effect on potassium levels • Thyroid hormones generally do not have a direct impact on potassium homeostasis. 5. Codeine phosphate → No significant effect on potassium levels • Opioids do not typically influence potassium balance in a way that causes hyperkalemia. Answer: Heparin causes hyperkalemia due to its inhibitory effect on aldosterone secretion.

Answer 12

The correct answer is pulmonary haemorrhage. Explanation: The carbon monoxide transfer factor (TLCO) measures the ability of the lungs to transfer carbon monoxide (CO) from alveolar air to the blood. It is influenced by factors such as alveolar surface area, capillary blood volume, and haemoglobin concentration. • Emphysema → Decreased TLCO • Destruction of alveolar walls reduces the surface area for gas exchange, leading to a lower TLCO. • Pulmonary embolism → Decreased TLCO • Reduced perfusion due to blocked pulmonary arteries decreases effective gas exchange. • Pulmonary haemorrhage → Increased TLCO • Alveolar haemorrhage increases the amount of haemoglobin in the alveoli, which binds CO more readily, artificially elevating TLCO. • Pneumonia → No consistent effect on TLCO • Localized inflammation and consolidation may mildly reduce TLCO, but this varies depending on severity and extent. • Pulmonary fibrosis → Decreased TLCO • Thickening of the alveolar-capillary membrane impairs gas diffusion, reducing TLCO. Thus, pulmonary haemorrhage is the only condition in this list that increases TLCO.

Answer 13

The most appropriate initial treatment for a 45-year-old female diagnosed with carcinoma of the caecum, where the tumour invades the muscularis propria with some regional lymphadenopathy, is right hemicolectomy. Explanation: • Right hemicolectomy: This is the standard treatment for a localized right-sided colon cancer, particularly when the tumor has invaded the muscularis propria and there is regional lymphadenopathy. Surgical resection is essential to remove the tumor and involved lymph nodes. • External beam radiotherapy: This is generally not the first-line treatment for colon cancer. It’s more commonly used in rectal cancer or for palliative purposes. • Chemotherapy: While chemotherapy is important for treating metastatic disease or as adjuvant therapy after surgery (if the tumor has spread to lymph nodes), it is not the initial treatment for localized colon cancer. • Combined long course chemo-radiotherapy: This is typically reserved for rectal cancer, not colon cancer, and is not the first-line treatment for a cecal carcinoma. • Referral for palliative care: This would only be appropriate if the cancer were metastatic or the patient were not a surgical candidate, which is not indicated in the given scenario. Thus, right hemicolectomy is the most appropriate initial treatment for this patient.

Answer 14

The best The best course of action in this case would be to undertake an ultrasound scan. Explanation: This 4-year-old girl presents with lethargy, abdominal pain, fever, and signs of right-sided peritonism, which raises concern for conditions such as appendicitis or a urinary tract infection (UTI). Let’s break down the options: • Manage as urinary tract infection with oral antibiotics: Although the urinanalysis is positive for leucocytes, which can suggest a UTI, the clinical signs of abdominal pain, fever, and peritonism are more concerning for an acute abdominal condition, such as appendicitis, which needs further investigation. • Manage as urinary tract infection with intravenous antibiotics: Given the patient’s clinical findings, an IV antibiotic approach might be appropriate if the patient were to be diagnosed with a serious UTI or sepsis. However, the primary concern here is still appendicitis, so antibiotics alone would not address the underlying issue without further evaluation. • Take to theatre for appendicectomy within 6 hours: This is premature without confirming the diagnosis of appendicitis. Although appendicitis is a strong possibility, a thorough diagnostic workup (like an ultrasound) is necessary before proceeding to surgery. • Undertake ultrasound scan: Ultrasound is the best initial diagnostic tool to assess for appendicitis, especially in children. It can help confirm the presence of an inflamed appendix or reveal other causes of abdominal pain, such as inflammatory bowel disease or urinary tract issues. • Admit for serial clinical examination: While serial examination might help monitor the patient’s progress, the clinical picture is concerning enough to warrant prompt imaging to rule out conditions like appendicitis before the situation worsens. Given the combination of peritonism, fever, and abdominal pain, an ultrasound scan should be performed urgently to evaluate for appendicitis or any other abdominal pathology.

Answer 15

The polyp type with the greatest risk of malignant transformation is villous adenoma. Explanation: • Hyperplastic polyp: These are generally considered benign and have a very low risk of malignant transformation. They are often found in the rectum and are typically not a concern for malignancy. • Tubular adenoma: This is the most common type of adenomatous polyp and is considered precancerous. However, its malignant potential is relatively lower compared to villous adenomas, particularly if it is small and has a tubular architecture. • Villous adenoma: These have the highest risk of malignant transformation among the polyp types listed. They are typically large, have a villous architecture, and have a higher propensity for dysplasia, which can progress to cancer. The malignant transformation rate is significantly higher, especially as they grow in size. • Hamartomatous polyp: These are benign growths composed of disorganized tissue. They do not have a significant risk of malignant transformation but can be associated with certain genetic syndromes, such as Peutz-Jeghers syndrome or Juvenile Polyposis Syndrome. • Pseudopolyp: These are non-neoplastic lesions that typically result from inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn’s disease. They have no malignant potential but can be associated with dysplasia in the background of IBD. Thus, villous adenomas carry the greatest risk of malignant transformation due to their larger size, villous structure, and higher likelihood of dysplasia.

Answer 16

The correct answer is Axillary vein. When a peripherally inserted central catheter (PICC) line is inserted into the basilic vein at the elbow and advanced, it most commonly passes into the axillary vein. The basilic vein continues proximally and becomes the axillary vein at the lower border of the teres major muscle. From there, the catheter will typically proceed into the subclavian vein, then into the brachiocephalic vein, and finally into the superior vena cava, where the catheter tip is ideally placed for central venous access oai_citation:0‡EMRCS and pas test MCQs -1.pdf.

Answer 17

The correct answer is Topical GTN (Glyceryl trinitrate). Explanation: This patient’s symptoms—bright red rectal bleeding post-defecation, severe pain, and a skin tag at the 6 o’clock position—are highly suggestive of a chronic anal fissure. Chronic anal fissures commonly occur in the posterior midline (6 o’clock position) and may be associated with a sentinel skin tag. Management: • First-line treatment: Topical GTN (0.2%) is commonly used as it helps to relax the internal anal sphincter, improving blood flow to the area and promoting healing. • Other conservative options: Stool softeners, dietary modifications (high-fiber diet), sitz baths, and topical local anesthetics. • Second-line options: If medical therapy fails, lateral internal sphincterotomy or Botox injections may be considered. Why not the other options? • Rubber band ligation – Used for internal hemorrhoids, not anal fissures. • Injections of oily phenol – Used for hemorrhoids, not fissures. • Milligan Morgan haemorrhoidectomy – A surgical procedure for severe hemorrhoids, not indicated here. • Lords anal dilatation – Outdated treatment for anal fissures, associated with incontinence risk. Thus, Topical GTN is the most appropriate treatment in this case.

Answer 18

The correct answer is Subtotal colectomy. Explanation: This patient has an obstructing carcinoma of the splenic flexure, and colonic stenting has failed, meaning an urgent surgical solution is required. Why subtotal colectomy is the best option: 1. Oncological clearance – A subtotal colectomy ensures removal of the entire colon up to the rectosigmoid junction, including the tumor and potential synchronous lesions or polyps. 2. Preventing future obstruction – Patients with left-sided colonic obstruction are at risk of having synchronous or metachronous lesions in other parts of the colon. Removing most of the colon prevents future obstruction. 3. Safe anastomosis – A subtotal colectomy with ileorectal anastomosis is preferable to avoid tension and ischemia, which can be problematic in an isolated left hemicolectomy. Why not the other options? • Extended right hemicolectomy – This includes the right colon, transverse colon, and splenic flexure, but does not adequately address descending and sigmoid colon disease, which could be problematic. • Standard right hemicolectomy – Does not address the splenic flexure. • Standard left hemicolectomy – While this removes the splenic flexure, it may leave behind the proximal colon, which could be poorly prepared and at risk for further obstruction. • Transverse colectomy – Rarely performed as a standalone procedure due to poor vascular supply and higher anastomotic failure rates. Conclusion: Subtotal colectomy with ileorectal anastomosis is the best approach for an obstructing splenic flexure cancer when stenting has failed, as it provides oncological clearance, reduces risk of future obstruction, and allows for a safer anastomosis.

Answer 19

The correct answer is: Commence resuscitation with intravenous fluids and then undertake a laparotomy 2-4 hours later. Explanation: This 75-year-old lady presents with large bowel obstruction (LBO) secondary to a hepatic flexure tumour, with a caecal diameter of 11 cm on imaging. This is a surgical emergency because: • The caecum is at risk of perforation when it exceeds 10-12 cm due to increased intraluminal pressure. • Large bowel obstruction can lead to bowel ischemia, necrosis, or perforation, requiring urgent surgical intervention. Best Approach: 1. Immediate resuscitation • Intravenous fluids to correct dehydration and electrolyte imbalances. • Nasogastric tube decompression if vomiting persists. • Broad-spectrum antibiotics (to cover gut flora in case of perforation). 2. Urgent surgery within 2-4 hours • Options include right hemicolectomy (standard oncological resection for hepatic flexure tumours) with primary anastomosis or stoma creation if the bowel is unhealthy. Why not the other options? • Immediate laparotomy – Without prior resuscitation, the patient is at higher risk of perioperative complications due to dehydration and electrolyte imbalances. • Delay surgery to the next day – This is unsafe as there is a high risk of perforation, leading to peritonitis and sepsis. • Colonoscopy – Not appropriate in an acute obstruction with a massively dilated caecum; could risk perforation. • Oral sodium picosulphate – A laxative is contraindicated in bowel obstruction and could worsen the condition by increasing intraluminal pressure. Conclusion: This patient requires urgent resuscitation followed by laparotomy within 2-4 hours to prevent caecal perforation and sepsis.

Answer 20

The correct answer is: Arrange a CT angiogram. Explanation: This 66-year-old man presents with massive lower gastrointestinal (GI) bleeding, which has persisted despite a normal upper GI endoscopy. In cases of severe lower GI bleeding, it is essential to identify the source before considering definitive treatment. Why CT angiography (CTA)? • First-line investigation for hemodynamically significant lower GI bleeding when the source is unclear. • Can localize the bleeding site if the bleeding rate is ≥ 0.3–0.5 mL/min. • Can help guide endovascular intervention (e.g., embolization) or surgical management if required. Why not the other options? • Laparotomy and subtotal colectomy – A last resort if the bleeding is uncontrollable and no clear source is identified. Subtotal colectomy is highly morbid and should be avoided unless life-threatening bleeding persists despite all interventions. • Colonoscopy – Can be done electively but is usually not helpful in massive bleeding because poor visualization limits its diagnostic and therapeutic potential. It is better suited for stable or slower bleeding cases. • Laparoscopy with on-table colonoscopy – Rarely used in emergencies. Requires a well-prepared colon, which is not feasible in this scenario. • Capsule endoscopy – Used mainly for small bowel bleeding when colonoscopy and upper GI endoscopy are inconclusive. However, it is not useful in massive bleeding as it cannot provide immediate localization or treatment. Conclusion: CT angiogram is the best next step to localize the bleeding source and guide either interventional radiology (embolization) or surgery if needed.

Answer 21

The correct answer is: Laparotomy with Low Anterior Resection (LAR) and Covering Loop Ileostomy. Explanation: This 65-year-old lady has a large bowel obstruction secondary to a mid-rectal tumor without metastatic disease. The goal of treatment is to provide curative resection while ensuring safe recovery from obstruction. Why Low Anterior Resection (LAR) with Covering Loop Ileostomy? • LAR is the standard surgical treatment for mid and upper rectal cancers when an oncological resection is feasible. • A covering loop ileostomy is typically formed to protect the low pelvic anastomosis and reduce the risk of anastomotic leakage, which is high in rectal surgery. • This approach preserves bowel continuity, improving long-term quality of life. Why not the other options? • Formation of a loop colostomy – This is only a temporary palliative measure for unresectable or frail patients. It does not provide curative intent. • Laparotomy and Hartmann’s procedure – Reserved for emergencies (e.g., perforation, sepsis) or in patients unfit for anastomosis. It results in a permanent colostomy with difficult future reversal. • Pan-proctocolectomy and end ileostomy – Only indicated in familial conditions (e.g., FAP or IBD) or extensive multifocal disease, not for isolated mid-rectal tumors. • LAR with end colostomy – This would be an abdominoperineal resection (APR), which is needed for low rectal tumors involving the anal sphincter, but not for mid-rectal tumors, where sphincter preservation is possible. Conclusion: Low Anterior Resection (LAR) with Covering Loop Ileostomy is the best option, allowing curative resection, preservation of bowel continuity, and protection against anastomotic leaks. Debate: Key says A

Answer 22

The correct answer is: Proceed to abdominoperineal excision of the rectum (ELAPE). Explanation: This 62-year-old man has a T2N0 rectal cancer located 2 cm from the anal verge. The key factor here is the tumor’s proximity to the anal verge, which makes sphincter-preserving surgery (like Low Anterior Resection, LAR) unfeasible due to the lack of a sufficient distal margin. Why ELAPE (Extralevator Abdominoperineal Excision)? • Tumors ≤ 4 cm from the anal verge often require abdominoperineal excision (APE) because a safe oncological margin cannot be achieved while preserving the sphincters. • ELAPE (extralevator APE) is a modified technique of APE that provides a more radical excision with better oncological clearance and reduced local recurrence rates. • Since the tumor is T2N0 (localized, no nodal spread), there is no need for neoadjuvant radiotherapy, and immediate surgery is recommended. Why not the other options? • Low Anterior Resection (LAR) + Loop Ileostomy – Not suitable because LAR requires a distal margin of at least 1–2 cm, which is not feasible with a tumor only 2 cm from the anal verge. • Hartmann’s Procedure – Typically used in emergency settings like perforation or obstruction. It is not a standard treatment for low rectal cancer. • Radical Radiotherapy + ELAPE – Neoadjuvant chemoradiotherapy is not necessary for a T2N0 tumor, as the goal is curative resection. • Radical Radiotherapy + LAR – Again, LAR is not an option due to the low position of the tumor, and radiotherapy is not required in T2N0 disease. Conclusion: For a T2N0 rectal cancer located 2 cm from the anal verge, abdominoperineal excision of the rectum (ELAPE) is the best approach, ensuring complete oncological clearance while avoiding inadequate sphincter preservation attempts.

Answer 23

The correct answer is: Undertake a subtotal colectomy and end ileostomy. Explanation: This 20-year-old man presents with severe ulcerative colitis (UC) complicated by toxic megacolon, which is a life-threatening condition requiring urgent surgical intervention. Why subtotal colectomy with end ileostomy? • Toxic megacolon is a surgical emergency, and the goal is to remove the diseased colon while minimizing perioperative morbidity. • Subtotal colectomy with end ileostomy is preferred in the acute setting because: • It removes the majority of the diseased colon, eliminating the immediate inflammatory burden. • It preserves the rectum, which can be managed later with either: • Completion proctectomy with ileal pouch-anal anastomosis (IPAA) (J-pouch) if the patient desires sphincter preservation. • Completion proctectomy with permanent end ileostomy if pouch formation is unsuitable. Why not the other options? • Double the steroid dose – The patient has failed medical therapy (5 days of IV steroids) and has now developed megacolon, meaning surgery is needed. Increasing steroids will delay necessary intervention and increase the risk of perforation and sepsis. • Loop ileostomy – This is not sufficient in toxic megacolon, as it does not remove the diseased, inflamed colon. • Subtotal colectomy with ileorectal anastomosis – The rectum remains inflamed, and an anastomosis in an inflamed field risks breakdown. In acute colitis, rectal preservation is only temporary. • Panproctocolectomy (PPC) with end ileostomy – Too extensive in an unstable patient. It is safer to perform a staged approach, starting with a subtotal colectomy, and then removing the rectum later when the patient is stable. Conclusion: For toxic megacolon in severe ulcerative colitis, subtotal colectomy with end ileostomy is the safest option, allowing stabilization before deciding on a definitive restorative or permanent procedure.

Answer 24

The correct answer is: Radical chemoradiotherapy. Explanation: This 55-year-old man has a T2 anal cancer with no metastatic disease. The standard first-line treatment for localized anal squamous cell carcinoma (SCC) is radical chemoradiotherapy (CRT), which has been shown to be highly effective for organ preservation and oncological control. Why Radical Chemoradiotherapy? • The Nigro Protocol (5-fluorouracil + mitomycin C + radiotherapy) is the standard treatment for T1–T3 anal SCC and achieves high cure rates (~80%) while preserving the anal sphincter. • Chemoradiotherapy is curative in the majority of cases and avoids the need for a permanent colostomy. • Surgery is reserved for persistent or recurrent disease. Why Not the Other Options? • Radical abdominoperineal excision of the anus and rectum (APE) – This is a salvage procedure for persistent or recurrent disease after chemoradiotherapy. It is not first-line treatment for T2 anal cancer. • Excision proctectomy – This is not a standard treatment for anal SCC. Local excision is only considered in very small T1 tumors without nodal involvement. • External beam irradiation alone – Inferior to chemoradiotherapy, as chemotherapy enhances the radiosensitivity of the tumor, leading to better outcomes. • Chemotherapy alone – Ineffective as a primary treatment; requires radiotherapy for curative intent. Conclusion: For T2N0M0 anal cancer, radical chemoradiotherapy (Nigro protocol) is the most appropriate treatment, achieving excellent oncological control while preserving sphincter function.

Answer 25

The most likely diagnosis is: Infection with Echinococcus granulosus (Hydatid disease). Explanation: This 30-year-old man from Greece presents with: • Colicky right upper quadrant (RUQ) pain – Suggestive of hepatobiliary involvement. • Jaundice – Indicates possible biliary obstruction. • Urticarial rash – Suggests an immune response, possibly to parasite rupture. • No response to ciprofloxacin – Suggests a non-bacterial cause. Given the geographic background (Greece), hydatid disease (Echinococcus granulosus) is highly likely. This parasite is endemic in Mediterranean countries, and humans acquire it from contact with infected dogs or contaminated food/water. Why Echinococcus granulosus? • Hydatid cysts commonly affect the liver (~70%), causing RUQ pain and biliary compression. • If the cyst ruptures into the biliary tree, it can cause jaundice, biliary obstruction, and anaphylactic reactions (urticaria, eosinophilia). • Secondary bacterial infection of a cyst can mimic a liver abscess but will not respond well to ciprofloxacin. Why Not the Other Options? • Wuchereria bancrofti infection – Causes lymphatic filariasis, presenting with lymphoedema, elephantiasis, and chyluria, not RUQ pain and jaundice. • Type III hypersensitivity reaction – Can cause urticarial rash, but does not explain RUQ pain and jaundice. • Allergy to ciprofloxacin – Would typically cause rash, angioedema, or anaphylaxis, but not jaundice or persistent RUQ pain. • Common bile duct (CBD) stones – Can cause biliary colic and jaundice, but do not explain the urticarial rash or lack of response to ciprofloxacin. Conclusion: This patient’s presentation is highly suggestive of hydatid disease (Echinococcus granulosus), likely due to rupture of a hepatic cyst into the biliary tree. Serology and imaging (CT/MRI) can confirm the diagnosis, and treatment involves albendazole and surgical or percutaneous cyst management (PAIR procedure).

Answer 26

The most likely diagnosis in this case is **benign oesophageal stricture**. ### Explanation: 1. **History of tracheo-oesophageal fistula (TOF) repair**: This is a key clue. TOF repair in infancy is often associated with oesophageal atresia, which can lead to complications such as oesophageal strictures later in life. Strictures can develop due to scarring or narrowing of the oesophagus after surgical repair. 2. **Sudden onset of dysphagia with a food bolus impaction**: This is a classic presentation of an oesophageal stricture. The stricture narrows the oesophageal lumen, making it difficult for food to pass, leading to impaction. 3. **Age and lack of significant history**: Squamous cell carcinoma and oesophageal adenocarcinoma are extremely rare in a 4-year-old child. Barrett's oesophagus is also unlikely in this age group and is typically associated with chronic gastro-oesophageal reflux disease (GORD). 4. **Achalasia**: While achalasia can cause dysphagia, it is less likely in this context. Achalasia typically presents with progressive dysphagia for both solids and liquids, and it is not associated with a history of TOF repair. ### Conclusion: The most likely diagnosis is **benign oesophageal stricture**, likely secondary to scarring from the previous TOF repair.

Answer 27

The correct statement is: **Biopsies may be non-diagnostic in over 50% of cases.** ### Explanation: 1. **Temporal artery biopsy is only diagnostic if there is visual loss**: This is incorrect. Temporal artery biopsy can be diagnostic even in the absence of visual loss. Visual loss is a severe complication of temporal arteritis but is not a prerequisite for diagnosis. 2. **Biopsy is typically taken from the non-symptomatic side to avoid the risk of blindness**: This is incorrect. The biopsy is usually taken from the symptomatic side (the side with tenderness, swelling, or other signs of inflammation) to maximize the chance of detecting pathology. The risk of blindness is not related to the side of the biopsy but to the disease itself. 3. **Pre-operative localisation with duplex is mandatory**: This is incorrect. While duplex ultrasound can be helpful in identifying areas of inflammation or stenosis in the temporal artery, it is not mandatory before a biopsy. The biopsy is often guided by clinical findings. 4. **Biopsies may be non-diagnostic in over 50% of cases**: This is correct. Temporal arteritis can involve the artery in a segmental or patchy manner, leading to "skip lesions." As a result, even if the disease is present, the biopsy may miss the affected segment, leading to a false-negative result in a significant proportion of cases. 5. **Biopsies are usually performed under general anaesthesia**: This is incorrect. Temporal artery biopsies are typically performed under local anaesthesia, as it is a relatively simple and quick procedure. ### Conclusion: The most accurate statement is that **biopsies may be non-diagnostic in over 50% of cases** due to the segmental nature of the disease.

Answer 28

The correct answer is: **E. Bulbocavernosus reflex** ### Explanation: 1. **Spinal shock**: This is a temporary loss of spinal reflexes, motor function, and sensation below the level of a spinal cord injury. It typically lasts from a few hours to several weeks. 2. **Bulbocavernosus reflex**: This is the **earliest reflex to recover** after spinal shock. It is a polysynaptic reflex mediated by the S2-S4 spinal cord segments. The reflex involves contraction of the bulbocavernosus muscle in response to squeezing the glans penis or clitoris or tugging on an indwelling Foley catheter. Its return signifies the end of spinal shock. 3. **Other reflexes**: - **Plantar reflex (A)**: This is a superficial reflex that tests the integrity of the corticospinal tract. It is not the earliest to recover. - **Ankle deep tendon reflex (B)**: This reflex tests the S1 nerve root and is not the first to recover. - **Biceps deep tendon reflex (C)**: This reflex tests the C5-C6 nerve roots and is not relevant in a C7 spinal cord injury. - **Delayed plantar reflex (D)**: This is not a recognized reflex. 4. **Why the bulbocavernosus reflex recovers first**: It is a primitive reflex that does not depend on higher cortical input, making it the first to return after spinal shock. ### Conclusion: The **bulbocavernosus reflex** is the earliest to recover following the spinal shock stage.

Answer 29

The most likely lesion to be present in this patient is: **Squamous cell carcinoma** ### Explanation: 1. **Achalasia and oesophageal malignancy**: Patients with long-standing achalasia are at an increased risk of developing oesophageal cancer, particularly **squamous cell carcinoma**. The risk is estimated to be 10-30 times higher than in the general population. 2. **Pathophysiology**: Chronic stasis of food in the oesophagus due to achalasia leads to irritation, inflammation, and mucosal damage, which can predispose to the development of squamous cell carcinoma. 3. **Adenocarcinoma (A)**: This type of cancer is more commonly associated with Barrett's oesophagus, which results from chronic gastro-oesophageal reflux disease (GORD), not achalasia. 4. **Gastrointestinal stromal tumour (B)**: These are rare mesenchymal tumours that can occur anywhere in the gastrointestinal tract but are not specifically associated with achalasia. 5. **Leiomyosarcoma (C)**: This is a rare malignant smooth muscle tumour that can occur in the oesophagus but is not specifically linked to achalasia. 6. **Rhabdomyosarcoma (D)**: This is a rare malignant tumour of skeletal muscle origin and is extremely uncommon in the oesophagus. ### Conclusion: Given the patient's history of long-standing achalasia, the most likely oesophageal malignancy is **squamous cell carcinoma**.

Answer 30

The most likely underlying cause in this case is: **Plummer-Vinson syndrome** ### Explanation: 1. **Clinical presentation**: The patient is a 32-year-old woman with dysphagia and a long history of iron deficiency anaemia secondary to menorrhagia. These are classic features of **Plummer-Vinson syndrome** (also known as Paterson-Kelly syndrome). 2. **Plummer-Vinson syndrome**: - Characterized by the triad of **dysphagia**, **iron deficiency anaemia**, and **oesophageal webs**. - The oesophageal webs are thin mucosal folds that can cause obstruction, leading to dysphagia, particularly for solids. - It is more common in middle-aged women and is strongly associated with iron deficiency. 3. **Other options**: - **Candidiasis (A)**: This typically occurs in immunocompromised individuals and presents with odynophagia (painful swallowing) rather than dysphagia. It is not associated with iron deficiency anaemia. - **Globus (B)**: This is a sensation of a lump in the throat without true dysphagia or structural abnormality. It is not associated with anaemia. - **Squamous cell carcinoma of the oesophagus (C)**: This is more common in older individuals with risk factors such as smoking, alcohol use, or long-standing achalasia. It is not typically associated with iron deficiency anaemia. - **Adenocarcinoma of the oesophagus (D)**: This is associated with Barrett's oesophagus and chronic gastro-oesophageal reflux disease (GORD), not iron deficiency anaemia. ### Conclusion: Given the patient's history of iron deficiency anaemia and dysphagia, the most likely diagnosis is **Plummer-Vinson syndrome**.

Answer 31

The correct answer is: **Macrophages** ### Explanation: 1. **Giant cells**: These are large, multinucleated cells that form through the fusion of monocytes or macrophages. They are typically seen in response to chronic inflammation, infections, or foreign bodies. 2. **Macrophages (D)**: Giant cells most commonly originate from macrophages. When macrophages encounter persistent stimuli (e.g., pathogens, foreign material, or chronic inflammation), they can fuse together to form multinucleated giant cells. Examples include: - **Langhans giant cells** (seen in tuberculosis). - **Foreign body giant cells** (seen in response to foreign material). - **Touton giant cells** (seen in xanthomas and fat necrosis). 3. **Other cell types**: - **Neutrophils (A)**: These are involved in acute inflammation and do not form giant cells. - **Myofibroblasts (B)**: These are involved in wound healing and fibrosis but do not form giant cells. - **Fibroblasts (C)**: These are responsible for producing extracellular matrix and collagen but do not form giant cells. - **Goblet cells (E)**: These are specialized epithelial cells that secrete mucus and are not involved in giant cell formation. ### Conclusion: Giant cells most commonly originate from **macrophages**.

Answer 32

The most likely underlying cause in this case is: **Direct arterial injury** ### Explanation: 1. **Clinical scenario**: A displaced supracondylar humeral fracture in a child is a serious injury that can lead to vascular compromise. The presence of a **cold and insensate hand with absent pulses** strongly suggests disruption of the brachial artery, which runs near the fracture site. 2. **Direct arterial injury (D)**: - The brachial artery is particularly vulnerable to injury in supracondylar fractures due to its proximity to the distal humerus. - A displaced fracture can stretch, compress, or lacerate the artery, leading to acute ischemia of the forearm and hand. - This is a surgical emergency requiring immediate reduction of the fracture and assessment of vascular integrity. 3. **Other options**: - **Clot embolus (A)**: While possible, this is less likely in the context of acute trauma and a displaced fracture. Emboli typically occur in the setting of atrial fibrillation or other cardiovascular conditions. - **Compartment syndrome (B)**: This can occur secondary to ischemia or swelling but is not the primary cause of the absent pulses and cold hand. Compartment syndrome would present with severe pain, pallor, paresthesia, and paralysis. - **Steal syndrome (C)**: This is a chronic condition seen in patients with arteriovenous fistulas and is not relevant in this acute traumatic setting. - **Vasospasm (E)**: While vasospasm can occur after trauma, it is unlikely to cause complete loss of pulses and a cold, insensate hand in the absence of direct arterial injury. ### Conclusion: The most likely cause of the cold, insensate hand with absent pulses in this child is **direct arterial injury** due to the displaced supracondylar humeral fracture. Immediate intervention is required to restore blood flow and prevent permanent damage.

Answer 33

The most appropriate treatment option for this patient is: **Subtotal gastrectomy, D2 lymphadenectomy, and Roux-en-Y reconstruction** ### Explanation: 1. **Gastric carcinoma of the greater curvature**: This is a localized gastric cancer, and the goal of treatment is curative resection. 2. **Staging investigations negative for metastatic disease**: This indicates that the cancer is potentially resectable with curative intent. 3. **Subtotal gastrectomy, D2 lymphadenectomy, and Roux-en-Y reconstruction**: - **Subtotal gastrectomy**: This involves removing the affected portion of the stomach, including the greater curvature, while preserving as much of the stomach as possible. - **D2 lymphadenectomy**: This is the standard surgical procedure for gastric cancer and involves removing the perigastric lymph nodes (D1) as well as additional lymph nodes along the major arteries supplying the stomach (D2). This is crucial for accurate staging and reducing the risk of recurrence. - **Roux-en-Y reconstruction**: This is a common method of restoring gastrointestinal continuity after gastrectomy. It involves creating a Y-shaped anastomosis between the remaining stomach, the jejunum, and the duodenum, which helps prevent bile reflux and improves postoperative function. 4. **Other options**: - **Radical radiotherapy (A)**: This is not typically used as primary treatment for localized gastric cancer. It may be used in palliative settings or in combination with chemotherapy (chemoradiation) in certain cases. - **Subtotal gastrectomy, D2 lymphadenectomy, and anterior gastrojejunostomy (C)**: Anterior gastrojejunostomy is not the standard reconstruction method for gastric cancer surgery. Roux-en-Y is preferred due to its advantages in reducing bile reflux. - **Oesophagogastrectomy (D)**: This is used for tumors involving the gastroesophageal junction or distal esophagus, not for tumors of the greater curvature of the stomach. - **Sleeve gastrectomy (E)**: This is a bariatric surgery procedure and is not appropriate for the treatment of gastric cancer. ### Conclusion: The most appropriate treatment for this patient is **subtotal gastrectomy, D2 lymphadenectomy, and Roux-en-Y reconstruction**. This approach offers the best chance for curative resection and long-term survival.

Answer 34

The most likely underlying cause in this case is: **Lumbar canal stenosis** ### Explanation: 1. **Clinical presentation**: The patient describes **neurogenic claudication**, which is characterized by: - **Bilateral calf pain** after walking a certain distance (e.g., 100 yards). - **Relief with bending forward** (e.g., leaning on a shopping cart or walking uphill), which increases the space in the lumbar spinal canal and reduces pressure on the nerves. - **Ability to ride a bike without pain**, as cycling involves a flexed posture that relieves nerve compression. 2. **Lumbar canal stenosis (A)**: - This condition involves narrowing of the spinal canal in the lumbar region, leading to compression of the nerve roots. - It is a classic cause of neurogenic claudication, which is often mistaken for vascular claudication (due to peripheral arterial disease). - Symptoms are typically relieved by sitting or bending forward and worsened by standing or walking. 3. **Other options**: - **Diabetic neuropathy (B)**: This typically causes symmetric sensory symptoms (e.g., numbness, tingling, or burning) rather than positional claudication. - **Aorto-iliac occlusion (C)**: This would cause **vascular claudication**, which is not relieved by bending forward and is typically associated with absent or diminished pulses in the lower limbs. - **Occlusion of the superficial femoral artery (D)**: This would also cause vascular claudication, typically in the calf, but it would not be relieved by bending forward. - **Pelvic rheumatoid arthritis (E)**: This is rare and would not typically present with claudication symptoms. It would more likely cause pain and stiffness in the pelvic joints. ### Conclusion: The patient’s symptoms are most consistent with **lumbar canal stenosis**, a condition that causes neurogenic claudication due to nerve root compression in the lumbar spine.

Answer 35

The process that best accounts for this presentation is: **Thrombosis** ### Explanation: 1. **Clinical scenario**: The patient has a known history of claudication and an 85% stenosis of the superficial femoral artery (SFA). He now presents with acute severe pain, absent pulses, and a cool limb, which are classic signs of **acute limb ischemia**. 2. **Thrombosis (A)**: - The severe stenosis in the SFA creates turbulent blood flow, which predisposes to the formation of a thrombus (blood clot) at the site of the stenosis. - The thrombus can acutely occlude the already narrowed artery, leading to sudden cessation of blood flow and acute limb ischemia. - This is consistent with the patient’s presentation of severe pain, absent pulses, and a cool limb. 3. **Other options**: - **Embolus (B)**: An embolus typically originates from a proximal source (e.g., the heart or aorta) and lodges in a distal artery. While it can cause acute limb ischemia, it is less likely in this case given the pre-existing severe stenosis in the SFA. - **Atheroma growth (C)**: Growth of an atheroma (plaque) is a gradual process and would not cause sudden onset of symptoms. - **Subintimal dissection (D)**: This is a rare complication of endovascular procedures and is unlikely to occur spontaneously in this context. - **Anaemia (E)**: Anaemia does not cause acute limb ischemia or the described symptoms. ### Conclusion: The most likely process accounting for this presentation is **thrombosis** of the superficial femoral artery at the site of pre-existing stenosis, leading to acute limb ischemia. This is a vascular emergency requiring urgent intervention (e.g., thrombectomy or thrombolysis).

Answer 36

The most likely cause in this case is: **Papillary carcinoma** ### Explanation: 1. **Clinical presentation**: The patient is a 20-year-old woman with a thyroid nodule and a small discrete mass separate from the thyroid gland. This is highly suggestive of **papillary thyroid carcinoma**, which is the most common type of thyroid cancer, particularly in young women. 2. **Papillary carcinoma (D)**: - Accounts for **80-85% of all thyroid cancers**. - Often presents as a solitary thyroid nodule. - Can spread to regional lymph nodes, which may present as discrete masses separate from the thyroid gland (as in this case). - Has an excellent prognosis, especially in young patients. 3. **Other options**: - **Follicular carcinoma (A)**: This is the second most common type of thyroid cancer but is less likely to present with lymph node involvement. It is more common in older patients. - **Anaplastic carcinoma (B)**: This is a rare, aggressive form of thyroid cancer that typically occurs in older patients and presents with rapid growth and local invasion. It is unlikely in a 20-year-old. - **Medullary carcinoma (C)**: This is a rare type of thyroid cancer that arises from parafollicular C cells. It can be sporadic or familial (associated with multiple endocrine neoplasia [MEN] syndromes). However, it is less common than papillary carcinoma and would typically present with elevated calcitonin levels. - **B-cell lymphoma (E)**: This is a rare cause of thyroid masses and is typically seen in older patients with a history of Hashimoto’s thyroiditis. ### Conclusion: The most likely diagnosis in this young patient with a thyroid nodule and a discrete mass separate from the gland is **papillary carcinoma**. This is the most common thyroid cancer in this age group and often presents with regional lymph node involvement.

Answer 37

The most appropriate treatment option for this patient is: **Total gastrectomy and Roux-en-Y reconstruction** ### Explanation: 1. **Tumour of the gastric cardia**: The gastric cardia is the region of the stomach that connects to the esophagus. Tumors in this location are often adenocarcinomas and require aggressive surgical management due to their proximity to the esophagus and the risk of local spread. 2. **No evidence of metastatic disease**: This indicates that the tumor is potentially resectable with curative intent. 3. **Total gastrectomy and Roux-en-Y reconstruction**: - **Total gastrectomy**: This involves complete removal of the stomach, including the cardia, to ensure clear margins and reduce the risk of local recurrence. - **Roux-en-Y reconstruction**: This is the standard method of restoring gastrointestinal continuity after total gastrectomy. It involves creating a Y-shaped anastomosis between the esophagus, the jejunum, and the duodenum, which helps prevent bile reflux and improves postoperative function. 4. **Other options**: - **Subtotal gastrectomy and Roux-en-Y reconstruction (A)**: This is not appropriate for tumors of the gastric cardia, as it does not provide adequate margins for resection. - **Total gastrectomy and loop jejunostomy reconstruction (C)**: This is not a standard reconstruction method and is less effective than Roux-en-Y in preventing bile reflux. - **Proximal gastrectomy and gastric pull-up (D)**: This is rarely performed due to the high risk of complications, such as reflux and anastomotic strictures. - **External beam radical radiotherapy (E)**: This is not a primary treatment for resectable gastric cancer. It may be used in palliative settings or in combination with chemotherapy (chemoradiation) in certain cases. ### Conclusion: The most appropriate treatment for this patient with a tumor of the gastric cardia is **total gastrectomy and Roux-en-Y reconstruction**. This approach offers the best chance for curative resection and long-term survival.

Answer 38

The condition described in this patient is most likely **Marfan syndrome**, and the primary defect is in: **Fibrillin** ### Explanation: 1. **Clinical features**: - **Tall stature**, **pectus excavatum** (sunken chest), and **arachnodactyly** (long, slender fingers and toes) are classic features of **Marfan syndrome**. - **Aortic dissection** is a life-threatening complication of Marfan syndrome due to weakening of the aortic wall. 2. **Marfan syndrome**: - This is an autosomal dominant connective tissue disorder caused by mutations in the **FBN1 gene**, which encodes the protein **fibrillin-1**. - Fibrillin-1 is a key component of microfibrils in the extracellular matrix, which provide structural support to tissues, including the aorta. - Defective fibrillin-1 leads to abnormal connective tissue, resulting in the characteristic features of Marfan syndrome and an increased risk of aortic dissection. 3. **Other proteins**: - **Polycystin-1 (A)**: Mutations in this protein are associated with autosomal dominant polycystic kidney disease (ADPKD), not Marfan syndrome. - **Type IV collagen (C)**: Defects in type IV collagen are associated with Alport syndrome, a condition affecting the kidneys and ears. - **Type I collagen (D)**: Mutations in type I collagen are seen in osteogenesis imperfecta, a condition characterized by brittle bones. - **Elastin (E)**: While elastin is important for tissue elasticity, defects in elastin are not the primary cause of Marfan syndrome. ### Conclusion: The primary defect in this patient’s condition is in **fibrillin**, which is the underlying cause of Marfan syndrome and its associated complications, such as aortic dissection.

Answer 39

Given the scenario of a 72-year-old man with a 6.6 cm abdominal aortic aneurysm (AAA) involving the right common iliac artery and an occluded left iliac artery, along with comorbidities of hypertension and well-controlled Type 2 diabetes mellitus, the best course of action is typically determined by the size and risk of rupture of the aneurysm. - **Size of Aneurysm**: A 6.6 cm AAA is considered large and has a significant risk of rupture. Generally, aneurysms larger than 5.5 cm are considered for repair due to the increased risk of rupture. - **Urgency**: Given the size, repair should be considered urgently, but not necessarily emergently unless there are signs of impending rupture. - **Type of Repair**: The choice between open surgical repair and endovascular aortic repair (EVAR) depends on several factors, including the patient's overall health, anatomy of the aneurysm, and surgical risks. EVAR is less invasive and often preferred for patients with suitable anatomy and higher surgical risk. Given these considerations, the most appropriate option would likely be: - **Endovascular aortic aneurysm repair in 48 hours**: This approach allows for a less invasive procedure, which may be beneficial given the patient's age and comorbidities. The urgency reflects the need to address the aneurysm promptly due to its size. However, the final decision should be made by the vascular surgery team based on a comprehensive evaluation of the patient's condition, aneurysm characteristics, and available treatment options.

Answer 40

The most appropriate operative treatment is Extended right hemicolectomy. Here's why: * Strong Family History: This patient has a very strong family history of young-onset colorectal and related cancers. This raises a high suspicion for Hereditary Non-Polyposis Colorectal Cancer (HNPCC), also known as Lynch syndrome. The brother's diagnosis of MSI-high (microsatellite instability) colorectal cancer further strengthens this suspicion, as MSI is a hallmark of Lynch syndrome. * Lynch Syndrome Implications: Lynch syndrome significantly increases the risk of synchronous (occurring at the same time) and metachronous (occurring later) colorectal cancers, as well as other cancers (endometrial, ovarian, stomach, etc.). Because of this increased risk throughout the colon, a more extensive resection is warranted. * Extended Right Hemicolectomy Rationale: A standard right hemicolectomy removes the cecum, ascending colon, and a portion of the transverse colon. An extended right hemicolectomy removes even more of the transverse colon, which is important in this case because of the Lynch syndrome risk. This wider resection aims to reduce the risk of future cancers developing in the remaining colon. Why other options are less suitable: * Limited ileocaecal resection: This is insufficient given the strong family history and risk of Lynch syndrome. It only removes a small portion of the bowel. * Right hemicolectomy: While better than a limited resection, it doesn't address the increased risk in the more distal colon due to Lynch syndrome. * Panproctocolectomy: This involves removing the entire colon and rectum. While it would eliminate the risk of future colorectal cancer, it's a more radical procedure with significant long-term consequences (requiring an ileostomy or ileoanal pouch). It's generally reserved for cases with rectal involvement or other specific indications, and not typically the first-line approach for a right-sided caecal cancer in this context. * Subtotal colectomy: This removes most of the colon but leaves the rectum. While it might be considered in some situations, an extended right hemicolectomy is more appropriate in this case because it addresses the location of the current cancer while also accounting for the Lynch syndrome risk in the remaining colon.

Answer 41

The most appropriate course of action is Excisional biopsy of the lesion. Here's why: * Concern for Melanoma: The surgeon's concern for melanoma necessitates complete removal of the lesion for accurate diagnosis and staging. Punch biopsies, while sometimes useful for initial characterization, are generally not the best approach for suspected melanomas. They may miss crucial information about the depth of invasion and other features that are critical for prognosis. * Excisional Biopsy Technique: An excisional biopsy involves removing the entire lesion, including a small margin of normal-appearing skin. This provides the pathologist with the entire lesion to examine, allowing for accurate diagnosis, Breslow thickness measurement (depth of invasion), and other important prognostic factors. * Margins: The appropriate margins for an excisional biopsy of a suspected melanoma are generally narrower than those used for definitive melanoma excision after diagnosis. A 1-3mm margin of normal skin is usually sufficient for the initial diagnostic excisional biopsy. The other options of 1cm or 3cm margins are generally not needed for the initial biopsy and would result in unnecessarily large scars. Why other options are incorrect: * 2mm or 4mm punch biopsy from the centre of the lesion: As mentioned above, punch biopsies are not ideal for suspected melanomas as they may not provide enough information for accurate diagnosis and staging. The entire lesion needs to be examined. * Wide excision of the lesion with 3cm or 1cm margins: Wide excision with larger margins is the treatment after a melanoma has been diagnosed, not for the initial diagnostic biopsy. Performing a wide excision before a diagnosis is confirmed is unnecessary and could lead to excessive scarring.

Answer 42

The correct answer is Capillary walls are more permeable. Here's why: * Increased Permeability in Inflammation: Paronychia and spreading sepsis represent an inflammatory response. A key characteristic of inflammation is increased permeability of capillary walls. This allows proteins and other large molecules, which normally remain within the bloodstream, to leak into the interstitial space (the tissue surrounding the capillaries). This leakage is what causes the higher protein content in the tissue exudate. Why the other options are less accurate: * Breakdown of tissue cells release protein: While tissue damage does release some proteins, this is not the primary reason for the increased protein content in exudate. The main source is leakage from the capillaries. * Increased blood flow transports more protein into the area: Increased blood flow delivers more everything to the area, including proteins, but it's the increased permeability that allows the proteins to leave the bloodstream and enter the tissue. Simply having more blood flow doesn't explain the disproportionately higher protein content in the exudate. * Intracapillary pressure is raised: While intracapillary pressure can be elevated in inflammation, it's not the primary mechanism causing the protein leakage. Increased permeability is the key factor. * Plasma cells release gamma globulin: Plasma cells do release gamma globulins (antibodies), but this is a more specific and later part of the immune response. While it contributes to the overall protein content, it's not the main reason for the increased protein in acute exudate. The increased capillary permeability is the immediate and most significant factor.

Answer 43

The most likely diagnosis is Periductal mastitis. Here's why: * Recurrent Infections and Smoking: Recurrent breast infections, especially in smokers, are highly suggestive of periductal mastitis (also known as plasma cell mastitis or mammary duct ectasia complex). Smoking is a known risk factor. * Indurated Area at Nipple-Areolar Complex: The location of the induration (firmness) at the lateral aspect of the nipple-areolar complex is characteristic of periductal mastitis. This is where the ducts converge. * No Mass Lesions on Imaging: The absence of mass lesions makes other diagnoses less likely. Periductal mastitis is primarily an inflammatory process, not a tumor. Why the other options are less likely: * Duct ectasia: While duct ectasia can be a component of periductal mastitis, it refers more specifically to the dilation of the milk ducts. The recurrent infections and induration point more towards the inflammatory process (periductal mastitis) itself. * Paget's disease of the nipple: Paget's disease is a rare form of breast cancer that presents with nipple changes (eczema-like rash, scaling, itching). It's less likely given the recurrent infections and the indurated area away from the nipple itself. It also usually presents with more obvious nipple changes. * Mondor's disease: Mondor's disease is a rare condition involving thrombophlebitis (inflammation and clotting) of a superficial vein in the breast or chest wall. It typically presents as a palpable, tender cord, not an indurated area. * Radial scar: Radial scars are benign breast lesions that can sometimes mimic cancer on imaging. However, they are not typically associated with recurrent infections. They are also usually not located directly at the nipple-areolar complex.

Answer 44

The underlying lesion is Hashimoto's thyroiditis. Here's why: * Lymphocytic Infiltrate, Acinar Destruction, and Fibrosis: These are the classic histological hallmarks of Hashimoto's thyroiditis. The lymphocytic infiltrate (mainly lymphocytes and plasma cells) attacks the thyroid follicles (acini), leading to their destruction and subsequent fibrosis (scarring). * Mild Goitre: Hashimoto's thyroiditis often presents with a goitre (enlarged thyroid gland), which can be mild. * Autoimmune Nature: Hashimoto's is an autoimmune disease, where the body's immune system attacks the thyroid gland. This explains the lymphocytic infiltrate and destruction of thyroid tissue. Why the other options are incorrect: * Anaplastic carcinoma: This is a very aggressive form of thyroid cancer. It would not typically present with the described histological features. Anaplastic carcinomas are usually much more undifferentiated and aggressive looking under the microscope. * Rhabdomyosarcoma: This is a rare malignant tumor of skeletal muscle. It does not arise in the thyroid gland. * Lymphoma: While lymphoma can affect the thyroid, the description of "acinar destruction" points strongly towards Hashimoto's. Lymphoma would typically present as a more diffuse infiltrate of lymphocytes without such prominent acinar destruction. * Graves' disease: Graves' disease is another autoimmune thyroid condition, but it is characterized by hyperthyroidism (overactive thyroid), not the destruction and fibrosis seen in Hashimoto's. Histologically, Graves' disease shows features of increased follicular activity, not destruction.

Answer 45

The most likely diagnosis is Glucagonoma. Here's why: * Diarrhoea, Weight Loss, and Skin Rash: These three symptoms together are highly suggestive of a glucagonoma. The skin rash is particularly characteristic; it's called necrolytic migratory erythema (NME). It often presents as erythematous (red), blistering lesions, especially on the face, groin, and extremities. The lesions can be irregular, with both intact and ruptured vesicles, as described. * Glucagonoma and NME: Glucagonomas are rare neuroendocrine tumors of the pancreas that produce excess glucagon. The elevated glucagon levels are responsible for the diabetes-like symptoms (which can include diarrhea), weight loss, and the distinctive NME rash. Why the other options are less likely: * Colonic adenocarcinoma: While colonic cancer can cause weight loss and sometimes diarrhea, it wouldn't typically present with the characteristic NME skin rash. * Pancreatic adenocarcinoma: Pancreatic cancer can also cause weight loss and sometimes diarrhea (due to malabsorption). However, like colon cancer, it wouldn't typically cause the NME rash. Also, pancreatic cancer often presents with abdominal pain and jaundice (if it obstructs the bile duct), which aren't mentioned here. * Tropical sprue: This is a malabsorption syndrome caused by an infection. It can cause diarrhea and weight loss, but it doesn't typically cause the specific NME skin rash. Tropical sprue also usually responds to antibiotic treatment. * Insulinoma: This is a tumor that produces excess insulin, leading to hypoglycemia (low blood sugar). The symptoms are typically related to this, such as sweating, tremors, confusion, and seizures. It would not cause diarrhea, weight loss, or the NME rash.

Answer 46

The most likely diagnostic modality to demonstrate the cause of dysphagia lusoria is CT angiogram. Here's why: * Dysphagia Lusoria Cause: Dysphagia lusoria is caused by an aberrant right subclavian artery, which arises from the aorta distal to the left subclavian artery and then courses behind the esophagus to reach the right arm. This abnormal artery can compress the esophagus, leading to swallowing difficulties. * CT Angiogram's Role: A CT angiogram is specifically designed to visualize blood vessels. It will clearly show the origin and course of the aberrant right subclavian artery, confirming the diagnosis of dysphagia lusoria. Why the other options are less suitable: * Upper GI endoscopy: Endoscopy visualizes the inside of the esophagus. While it might show indirect signs of external compression (like a pulsating indentation), it won't directly visualize the aberrant vessel itself. * Barium swallow: A barium swallow can also show indirect signs of compression on the esophagus, but it's not as sensitive or specific as a CT angiogram for visualizing the blood vessel. It's better for assessing the lumen of the esophagus. * Capsule endoscopy: This is primarily used to visualize the small intestine. It's not helpful for diagnosing esophageal compression. * Oesophageal manometry: This measures the pressure and motor function of the esophagus. It can detect abnormalities in esophageal motility, but it won't directly show the cause of external compression like an aberrant artery.

Answer 47

The clinical scenario described suggests a ruptured abdominal aortic aneurysm (AAA), which is a surgical emergency. The patient is in hypovolemic shock, as indicated by the low blood pressure (90/60 mmHg) and tachycardia (pulse rate of 105 beats per minute). The priority in this situation is rapid fluid resuscitation to restore circulating volume and maintain perfusion to vital organs while awaiting definitive surgical repair. Among the options provided, the most appropriate intravenous fluid regimen would be the one that allows for rapid volume expansion. - **1 Litre of pentastarch over 15 minutes**: This is a colloid solution that can rapidly expand plasma volume. However, colloids like pentastarch can have side effects such as anaphylactoid reactions and may not be the first choice in this emergency setting. - **1 litre of Hartmans solution over 4 hours**: This is a crystalloid solution, but the infusion rate is too slow for this emergency situation. - **1 litre of gelofusin over 30 minutes**: Gelofusin is another colloid solution, but similar to pentastarch, it may not be the first choice due to potential side effects. - **1 litre of Hartmans solution over 30 minutes**: This is a crystalloid solution and can be given rapidly to restore circulating volume. Hartmann's solution is balanced and less likely to cause electrolyte imbalances compared to normal saline. - **1 litre of blood over 15 minutes**: Blood transfusion would be ideal as it replaces lost blood volume and improves oxygen-carrying capacity. However, crossmatching and availability might delay administration. Given the options, **1 litre of Hartmans solution over 30 minutes** is the most appropriate choice for rapid volume resuscitation while waiting for operative repair. It allows for quick administration of a balanced crystalloid solution to stabilize the patient's hemodynamics. However, in a real clinical setting, blood transfusion would be the preferred option if immediately available.

Answer 48

The best course of action is Reassure and discharge. Here's why: * Greenish Nipple Discharge, Normal Exam, U1 Ultrasound: Greenish nipple discharge, especially if it's non-bloody and occurs only once, is often benign. A normal clinical breast exam and a U1 ultrasound (which indicates a normal ultrasound) further support a benign process. In this age group, it is very likely to be physiological. * Reassurance: Reassurance is key in this situation. The patient should be informed that the discharge is likely benign given the normal examination and ultrasound. Why other options are not the best course of action: * Arrange a mammogram: Mammograms are generally not indicated in women under 40 unless there are specific high-risk factors or concerning clinical findings. A single episode of greenish discharge with a normal exam and ultrasound does not warrant a mammogram in this age group. * Undertake a total duct excision: This is a major surgical procedure and is only indicated for persistent, troublesome nipple discharge, especially if it is bloody or associated with other concerning findings. It is far too invasive for a single episode of greenish discharge with normal clinical and ultrasound findings. * Undertake a microdochectomy: This is a less extensive procedure than total duct excision, involving removal of a single duct. However, it is still an invasive procedure and is not indicated for this presentation. * Express duct fluid for cytology: Cytology of nipple discharge is sometimes performed, especially if the discharge is bloody or there are other concerning features. However, in this case, the discharge is described as greenish, and the clinical examination and ultrasound are normal. Therefore, cytology is not necessary at this point. Reassurance is the most appropriate step.

Answer 49

The most appropriate management in this scenario is B. 2 liters of ringer lactate. Here's why: * Suspected Ruptured AAA: The combination of collapse, low blood pressure, high heart rate, and a pulsatile epigastric mass strongly suggests a ruptured abdominal aortic aneurysm (AAA). This is a life-threatening emergency. * Initial Management: The immediate priority is to stabilize the patient by restoring circulating volume and blood pressure. This is best achieved with rapid infusion of crystalloid fluids. * Ringer Lactate: Ringer lactate (also known as Hartmann's solution) is a balanced crystalloid solution that is commonly used for initial fluid resuscitation in trauma and surgical emergencies. It helps to restore fluid volume and electrolytes. * Why not other options: * 0.9% saline: While saline can be used, Ringer lactate is generally preferred due to its more balanced electrolyte composition. * Group O negative red cells: Blood transfusion is essential, but it shouldn't be the initial management. Fluid resuscitation should be started first to restore some circulating volume before blood products are given. Uncrossmatched O-negative blood can be used in dire situations, but crystalloid is the first step. * Platelets: Platelets are not indicated in this situation unless there is evidence of significant coagulopathy. * Prothrombin complex concentrate: This is used to reverse the effects of anticoagulants, which is not relevant in this acute scenario.

Answer 50

The most common childhood brain tumor among the options provided is **Medulloblastoma**. Medulloblastoma is a type of embryonal tumor that typically arises in the cerebellum, which is the part of the brain responsible for coordinating movement. It is most commonly diagnosed in children, particularly between the ages of 3 and 8, though it can occur in adults as well. Here’s a brief overview of the other options for context: - **Glioblastoma multiforme**: This is a highly aggressive brain tumor that is more common in adults than in children. - **Astrocytoma**: This is a type of glioma that can occur in both children and adults, but it is not the most common childhood brain tumor. - **Ependymoma**: This tumor arises from the ependymal cells lining the ventricles of the brain and the central canal of the spinal cord. It can occur in children but is less common than medulloblastoma. - **Meningioma**: This is a tumor that arises from the meninges, the protective layers surrounding the brain and spinal cord. It is more common in adults and is rare in children. Thus, **Medulloblastoma** is the most common childhood brain tumor among the listed options.

Answer 51

The most likely diagnosis in this case is **Thyroid gland lymphoma**. Here’s why: - **CD20 positivity**: CD20 is a marker expressed on B-cells, and its presence suggests a B-cell lymphoma. Thyroid gland lymphoma is a type of non-Hodgkin lymphoma that arises from B-cells within the thyroid gland. - **Clinical presentation**: The patient is a 55-year-old woman with a neck mass and enlarged deep cervical lymph nodes, which is consistent with lymphoma. Thyroid lymphomas often present with rapid enlargement of the thyroid gland and may be associated with symptoms of compression, such as difficulty swallowing or breathing. - **Association with Hashimoto's thyroiditis**: Thyroid lymphoma is frequently associated with Hashimoto's thyroiditis, a chronic autoimmune thyroiditis. Patients with Hashimoto's thyroiditis have an increased risk of developing thyroid lymphoma. Let’s briefly consider the other options: - **Hashimoto's thyroiditis**: This is an autoimmune condition that can cause thyroid enlargement (goiter), but it does not typically present with CD20-positive lymph nodes or rapid neck mass enlargement. - **Papillary thyroid cancer**: This is the most common type of thyroid cancer, but it is not associated with CD20 positivity. It typically presents as a thyroid nodule rather than diffuse thyroid enlargement with lymphadenopathy. - **Follicular thyroid cancer**: This is another type of thyroid cancer that presents as a thyroid nodule, but it is not associated with CD20 positivity. - **Anaplastic thyroid cancer**: This is a rare and aggressive form of thyroid cancer that can present with rapid thyroid enlargement and lymphadenopathy, but it is not CD20 positive. Given the CD20 positivity and the clinical presentation, **Thyroid gland lymphoma** is the most likely diagnosis.

Answer 52

The clinical scenario described involves a 32-year-old male who sustained an injury to his distal forearm after falling on an outstretched hand. The key findings on examination are: 1. Inability to lift the thumb off the table while the palm is facing downward. 2. Inability to move the interphalangeal joint of the thumb when the proximal phalanx is fixed. These findings suggest a loss of function in the **extensor pollicis longus (EPL) tendon**, which is responsible for extending the interphalangeal joint of the thumb and assisting in thumb abduction. The EPL tendon is particularly vulnerable to injury in distal forearm trauma, especially near the wrist. ### Explanation of the options: - **A. Radial nerve injury**: A radial nerve injury would typically cause weakness in wrist extension and finger extension, not just isolated thumb dysfunction. This is less likely given the specific findings. - **B. Posterior interosseous nerve injury**: This would affect multiple extensor muscles in the forearm but would not selectively spare other functions while causing isolated thumb dysfunction. - **C. Abductor pollicis brevis tendon tear**: This muscle is innervated by the median nerve and is involved in thumb abduction, not extension. It does not explain the inability to extend the interphalangeal joint. - **D. Extensor pollicis longus tendon tear**: This is the most likely cause. The EPL tendon is responsible for extending the interphalangeal joint of the thumb and is commonly injured in distal forearm trauma. - **E. Extensor pollicis brevis tendon tear**: The EPB tendon assists in thumb extension but primarily acts on the metacarpophalangeal joint, not the interphalangeal joint. ### Correct Answer: **D. Extensor pollicis longus tendon tear**

Answer 53

The clinical scenario involves a 43-year-old male who is unable to shrug his left shoulder following a **supraclavicular lymph node (LN) dissection**. This suggests injury to the **accessory nerve (cranial nerve XI)**, which innervates the **trapezius muscle**. The trapezius muscle is primarily responsible for elevating the shoulder (shrugging) and stabilizing the scapula. ### Explanation of the options: - **A. Loss of neck flexion**: Neck flexion is primarily controlled by the sternocleidomastoid muscle (also innervated by the accessory nerve) and other cervical muscles. However, the inability to shrug the shoulder is more specific to trapezius dysfunction. - **B. Inability to rotate the face towards the right side**: The sternocleidomastoid muscle (innervated by the accessory nerve) is responsible for rotating the face to the opposite side. If the left sternocleidomastoid is affected, the patient would have difficulty rotating the face to the **right side**. - **C. Inability to rotate the face towards the left side**: This would occur if the **right** sternocleidomastoid muscle were affected, which is not the case here. - **D. Loss of sensation over upper lateral shoulder**: This would suggest injury to the **supraclavicular nerves** (branches of the cervical plexus), not the accessory nerve. - **E. Inability to shrug the other shoulder**: The accessory nerve innervates the trapezius muscle on the same side. Injury to the left accessory nerve would not affect the right shoulder. ### Correct Answer: **B. Inability to rotate the face towards the right side** This is because the left sternocleidomastoid muscle, innervated by the left accessory nerve, is responsible for rotating the face to the right side. Injury to the left accessory nerve during supraclavicular LN dissection would impair this function.

Answer 54

The clinical scenario describes a **complicated appendicular mass with purulent content**, which is highly suggestive of **acute appendicitis** with abscess formation. The most likely organisms involved in such infections are **polymicrobial**, typically including **Gram-negative enteric bacteria** and **anaerobes**. ### Explanation of the options: - **A. Streptococcus pyogenes**: This is a Gram-positive bacterium that causes pharyngitis, skin infections, and other conditions but is not typically associated with appendicitis or intra-abdominal abscesses. - **B. Bacteroides**: This is a genus of **anaerobic Gram-negative bacteria** that is commonly found in the gastrointestinal tract and is a frequent contributor to intra-abdominal infections, including appendicitis and abscesses. - **C. Clostridium difficile**: This is an anaerobic Gram-positive bacterium that causes antibiotic-associated diarrhea and colitis, not appendicitis or abscesses. - **D. Staphylococcus aureus**: This is a Gram-positive bacterium that causes skin and soft tissue infections, but it is not typically associated with appendicitis or intra-abdominal infections. - **E. Salmonella**: This is a Gram-negative bacterium that causes gastroenteritis and enteric fever but is not a common cause of appendicitis or abscess formation. ### Correct Answer: **B. Bacteroides** Bacteroides species, along with other anaerobes (e.g., *Prevotella*, *Fusobacterium*) and facultative Gram-negative rods (e.g., *Escherichia coli*), are the most likely organisms found in a complicated appendicular mass with purulent content. These organisms are part of the normal gut flora and are commonly implicated in intra-abdominal infections.

Answer 55

In a patient with **bacterial infective endocarditis** and a **penicillin allergy**, the choice of antibiotic must avoid cross-reactivity with penicillin while effectively treating the infection. The culture revealed sensitivity to **amoxicillin**, which is a penicillin-class antibiotic, so alternatives must be carefully selected. ### Explanation of the options: 1. **Amoxicillin**: This is a penicillin-class antibiotic and is **contraindicated** in patients with a penicillin allergy due to the risk of hypersensitivity reactions. 2. **Linezolid**: This is an **oxazolidinone antibiotic** effective against Gram-positive bacteria, including streptococci and staphylococci. It is not related to penicillin and is a reasonable alternative in penicillin-allergic patients. 3. **Cefuroxime**: This is a **second-generation cephalosporin**. While cephalosporins are generally safe in patients with a non-severe penicillin allergy, there is a **5-10% cross-reactivity risk** with penicillin. Therefore, it should be avoided in patients with a documented penicillin allergy unless the allergy is mild (e.g., rash only). 4. **Gentamicin**: This is an **aminoglycoside antibiotic** often used in combination with other antibiotics for synergistic effects in endocarditis. However, it is not typically used as monotherapy for endocarditis. 5. **Cephalosporin**: This is a broad class of antibiotics, and like cefuroxime, there is a risk of cross-reactivity with penicillin. It should be avoided in patients with a penicillin allergy unless the allergy is mild. ### Correct Answer: **Linezolid** Linezolid is a safe and effective alternative for treating Gram-positive bacterial infections, including infective endocarditis, in patients with a penicillin allergy. It does not cross-react with penicillin and is effective against many of the organisms responsible for endocarditis (e.g., streptococci and staphylococci). ### Additional Considerations: - If the patient has a **severe penicillin allergy** (e.g., anaphylaxis), **vancomycin** is another alternative that is commonly used for endocarditis caused by Gram-positive organisms. - Always consider consulting an infectious disease specialist for complex cases like infective endocarditis.

Answer 56

A **pharyngeal pouch** (also known as **Zenker's diverticulum**) is an outpouching of the mucosa through the **Killian's dehiscence**, a weak area in the posterior pharyngeal wall. It typically presents with symptoms such as dysphagia, regurgitation of undigested food, and sometimes a palpable neck mass. The most appropriate investigation for diagnosing a pharyngeal pouch is one that allows visualization of the pouch and its relationship to the surrounding structures. ### Explanation of the options: 1. **Upper GI endoscopy with flexible endoscope**: This is not ideal for diagnosing a pharyngeal pouch because the flexible endoscope may miss the pouch or even inadvertently enter it, increasing the risk of perforation. 2. **Upper GI endoscopy with rigid endoscope**: Rigid endoscopy can be used to visualize the pharyngeal pouch, but it carries a higher risk of complications, such as perforation, and is not the first-line investigation. 3. **Upper GI fluoroscopic swallowing study (barium swallow)**: This is the **most appropriate investigation** for diagnosing a pharyngeal pouch. It allows dynamic visualization of the swallowing process and can clearly show the pouch, its size, and its relationship to the esophagus. 4. **Oesophageal manometry**: This measures pressure within the esophagus and is used to evaluate motility disorders, not structural abnormalities like a pharyngeal pouch. 5. **CT scan of the neck**: While a CT scan can provide detailed anatomical information, it is not the first-line investigation for a pharyngeal pouch. It may be used in complex cases or to assess complications. ### Correct Answer: **Upper GI fluoroscopic swallowing study (barium swallow)** This is the gold standard for diagnosing a pharyngeal pouch. It is non-invasive, provides dynamic imaging, and clearly demonstrates the pouch and its relationship to the esophagus.

Answer 57

The clinical scenario describes a **24-year-old woman from Western India** with **hypertension (176/128 mmHg)**, **absent peripheral pulses**, a **systolic heart murmur**, and symptoms of **lethargy and dizziness** worsened by head movement. These findings are highly suggestive of **Takayasu's arteritis**, a chronic inflammatory disease affecting the large arteries, particularly the aorta and its branches. ### Explanation of the options: 1. **Subclavian steal syndrome**: This occurs when there is stenosis or occlusion of the subclavian artery proximal to the vertebral artery, leading to reversed flow in the vertebral artery. It can cause dizziness, but it does not typically present with hypertension, absent peripheral pulses, or a systolic murmur. 2. **Aortic coarctation**: This is a congenital narrowing of the aorta, usually distal to the left subclavian artery. It causes hypertension in the upper extremities and weak or absent pulses in the lower extremities. However, it does not typically present with systemic symptoms like lethargy or dizziness. 3. **Patent ductus arteriosus**: This is a congenital condition where the ductus arteriosus fails to close after birth, leading to a left-to-right shunt. It causes a continuous murmur, not a systolic murmur, and does not present with hypertension or absent pulses. 4. **Aortic dissection**: This is a life-threatening condition where there is a tear in the aortic wall. It typically presents with severe, tearing chest pain and asymmetric blood pressures, not the chronic symptoms described here. 5. **Takayasu's arteritis**: This is a **large-vessel vasculitis** that primarily affects young women, particularly those of Asian descent. It causes inflammation and stenosis of the aorta and its branches, leading to **hypertension**, **absent peripheral pulses**, **bruits**, and systemic symptoms like lethargy and dizziness. The systolic murmur is due to turbulent flow through stenotic vessels. ### Correct Answer: **Takayasu's arteritis** This is the most likely diagnosis given the patient's demographic (young woman from Western India), symptoms (lethargy, dizziness), and clinical findings (hypertension, absent peripheral pulses, systolic murmur). Takayasu's arteritis is a chronic condition that requires prompt diagnosis and treatment to prevent complications such as stroke, heart failure, or organ damage.

Answer 58

The clinical scenario describes a **73-year-old woman** with **severe abdominal pain** and findings of **widespread necrosis of the small bowel and right colon** during laparotomy. This pattern of bowel necrosis is most consistent with **acute mesenteric ischemia**, which is typically caused by a sudden interruption of blood supply to the intestines. The most likely explanation for this finding is **acute embolism affecting the superior mesenteric artery (SMA)**. ### Explanation of the options: 1. **Mesenteric vein thrombosis**: This causes venous congestion and ischemia but typically progresses more slowly than arterial occlusion. It is less likely to cause sudden, widespread necrosis of the small bowel and right colon. 2. **Acute embolism affecting the superior mesenteric artery**: This is the **most likely explanation**. An embolus (often from a cardiac source, such as atrial fibrillation) can acutely occlude the SMA, leading to sudden and severe ischemia of the small bowel and right colon, which are supplied by this artery. 3. **Acute on chronic thrombus of the superior mesenteric artery**: This refers to a sudden thrombus forming on top of a pre-existing chronic stenosis. While it can cause acute ischemia, it is less common than an embolic event and typically occurs in patients with a history of chronic mesenteric ischemia (e.g., postprandial pain, weight loss). 4. **Subintimal dissection of the superior mesenteric artery**: This is a rare cause of mesenteric ischemia and is more likely to occur in patients with underlying vascular pathology (e.g., fibromuscular dysplasia). It is not the most likely explanation in this case. 5. **Proximal migration of abdominal aortic aneurysm**: This is not a recognized cause of acute mesenteric ischemia. An abdominal aortic aneurysm (AAA) can cause complications such as rupture or distal embolization, but it would not explain the widespread bowel necrosis described here. ### Correct Answer: **Acute embolism affecting the superior mesenteric artery** Acute embolism to the SMA is the most common cause of acute mesenteric ischemia and fits the clinical scenario of sudden, severe abdominal pain and widespread bowel necrosis. The SMA supplies the small bowel and right colon, making it the most likely vessel involved in this case.

Answer 59

The clinical scenario describes a **66-year-old woman** with **hip pain**, **tenderness on internal rotation**, and **markedly elevated serum calcium and alkaline phosphatase levels**. These findings are highly suggestive of a **bone pathology** with increased bone turnover. The most likely cause in this context is **metastatic breast cancer**. ### Explanation of the options: 1. **Metastatic breast cancer**: This is the **most likely cause**. Breast cancer commonly metastasizes to bone, leading to **osteolytic lesions** that cause pain, elevated calcium levels (due to bone resorption), and elevated alkaline phosphatase (due to increased bone turnover). The hip is a common site for metastatic disease. 2. **Chondrosarcoma**: This is a primary bone tumor that typically presents with pain and swelling. However, it does not usually cause systemic biochemical changes like elevated calcium and alkaline phosphatase levels. 3. **Osteoporosis**: This condition causes reduced bone density and an increased risk of fractures but does not typically cause elevated calcium or alkaline phosphatase levels. It also does not cause localized pain or tenderness unless a fracture has occurred. 4. **Paget's disease**: This is a chronic bone disorder characterized by increased bone remodeling, which can lead to elevated alkaline phosphatase levels. However, it rarely causes hypercalcemia unless the patient is immobilized. It also typically affects multiple bones and is less likely to present with isolated hip pain. 5. **Rickets**: This is a childhood condition caused by vitamin D deficiency, leading to defective bone mineralization. It is not relevant in a 66-year-old woman. ### Correct Answer: **Metastatic breast cancer** This is the most likely diagnosis given the patient's age, gender, clinical presentation (hip pain, tenderness on internal rotation), and biochemical findings (elevated calcium and alkaline phosphatase levels). Breast cancer is a common malignancy in women and frequently metastasizes to bone, causing osteolytic lesions and systemic biochemical changes. Further imaging (e.g., X-ray, MRI, or bone scan) and biopsy would be needed to confirm the diagnosis.

Answer 60

Fracture healing is a complex process that involves several stages, including inflammation, soft callus formation, hard callus formation, and remodeling. The **fracture callus** is the new bone tissue that forms at the fracture site, bridging the gap between the broken bone ends. It becomes visible on radiographs during the **soft callus formation** stage. ### Key Points: - **1 day**: At this early stage, the fracture site is in the **inflammatory phase**, and no callus is visible on radiographs. - **7 days**: By this time, the **soft callus** begins to form, but it is not yet visible on radiographs. - **3 weeks**: This is the **most likely time** when the **fracture callus** first becomes visible radiologically. The soft callus (composed of cartilage and fibrous tissue) starts to mineralize, forming a visible bridge on X-rays. - **6 weeks**: By this stage, the **hard callus** is well-formed and clearly visible on radiographs. - **8 weeks**: The callus is fully mature, and the bone is in the **remodeling phase**, where the callus is gradually replaced by mature bone. ### Correct Answer: **3 weeks** The fracture callus typically becomes visible on radiographs around **2-3 weeks** after the injury, during the transition from soft callus to hard callus formation. This corresponds to the mineralization of the soft callus, making it detectable on X-rays.

Answer 61

The clinical scenario describes a **40-year-old man** with a history of **Lynch syndrome** (hereditary non-polyposis colorectal cancer, HNPCC) and a previous **mucinous right-sided colonic carcinoma** treated with a right hemicolectomy. He now presents with **obstructive jaundice** and **dysphagia**. Given his history of Lynch syndrome, which predisposes him to various cancers, the most likely cause of his jaundice is **duodenal carcinoma**. ### Explanation of the options: 1. **Hepatocellular carcinoma (HCC)**: HCC typically presents with symptoms of liver dysfunction (e.g., jaundice, ascites) but is not associated with dysphagia. It is also less likely in a patient without chronic liver disease or cirrhosis. 2. **Liver metastasis from colonic cancer**: While liver metastases are common in colorectal cancer, they typically cause jaundice by compressing the biliary tree. However, they do not explain the dysphagia, and the recent normal colonoscopy makes recurrent colonic cancer less likely. 3. **Pancreatic carcinoma**: Pancreatic cancer can cause obstructive jaundice due to compression of the common bile duct. However, it does not typically cause dysphagia unless it involves the stomach or esophagus, which is less common. 4. **Duodenal carcinoma**: This is the **most likely cause**. Lynch syndrome is associated with an increased risk of duodenal and small bowel cancers. A duodenal carcinoma can cause **obstructive jaundice** by compressing the ampulla of Vater and **dysphagia** by extending into the stomach or esophagus. 5. **Metastatic gastric carcinoma**: Gastric cancer can cause dysphagia and, if it metastasizes to the liver, jaundice. However, the recent normal colonoscopy and the absence of gastric symptoms make this less likely. ### Correct Answer: **Duodenal carcinoma** Lynch syndrome is associated with an increased risk of duodenal and small bowel cancers. A duodenal carcinoma can cause both **obstructive jaundice** (by compressing the biliary tree) and **dysphagia** (by invading or compressing adjacent structures). Further investigations, such as **upper endoscopy** and **imaging**, would be needed to confirm the diagnosis.

Answer 62

The most likely pathological process present in the causative lesion is heterotopia. Here's why: * Heterotopia: This refers to the presence of tissue in an abnormal location. In the context of the terminal ileum, gastric or pancreatic heterotopia can occur. This misplaced tissue can be a source of bleeding, even if the surrounding mucosa looks normal on colonoscopy. The presence of fresh blood without an obvious mucosal lesion points towards a submucosal or less visible source, which heterotopic tissue could explain. Why the other options are less likely: * Metaplasia: This is a reversible change from one mature cell type to another. It's often a response to chronic irritation. While it can occur in the GI tract, it's less likely to cause significant fresh bleeding in the terminal ileum without other more noticeable endoscopic findings. * Dysplasia: This refers to disordered cell growth and is a precursor to cancer. While it can bleed, it usually presents with more visible mucosal abnormalities (e.g., polyps, ulcerations) rather than just fresh blood in a seemingly normal-looking terminal ileum. * Anaplasia: This is a characteristic of malignant cells, representing a loss of differentiation. Like dysplasia, it would typically be associated with more obvious endoscopic changes. * Atrophy: This is a decrease in cell size. While it can sometimes lead to subtle changes in the mucosa, it's not a common cause of fresh bleeding. Therefore, the most likely explanation for fresh blood in the terminal ileum with normal mucosa and a normal OGD in a 14-year-old is heterotopic tissue.

Answer 63

This is for informational purposes only. For medical advice or diagnosis, consult a professional. The underlying cause is Follicular carcinoma. Here's why: * Oxyphil cells: These are also known as Hürthle cells, which are thyroid follicular cells with abundant granular, eosinophilic cytoplasm due to a high number of mitochondria. * Scanty thyroid colloid: Colloid is a substance stored in the thyroid follicles that contains thyroglobulin, the precursor to thyroid hormones. A decrease in colloid suggests less hormone production or storage. These features are commonly associated with follicular carcinoma, a type of thyroid cancer that often exhibits these characteristics. Let's look at why the other options are less likely: * Papillary carcinoma: This is the most common type of thyroid cancer, but it typically presents with distinct features like papillary structures and psammoma bodies, not prominent oxyphil cells. * Lymphoma: This is a cancer of the lymphatic system and would likely involve other signs and symptoms related to the lymphatic system, such as enlarged lymph nodes. * Thyroiditis: This is inflammation of the thyroid gland and can have various causes. While oxyphil cells might be present in some types of thyroiditis, it wouldn't be the dominant feature. * Graves' disease: This is an autoimmune disorder that causes hyperthyroidism. While it can lead to changes in the thyroid gland, it wouldn't primarily present with a mass of oxyphil cells and scanty colloid. Important Note: This is a simplified explanation based on the information provided. A definitive diagnosis would require a thorough pathological examination of the thyroid specimen.

Answer 64

This is for informational purposes only. For medical advice or diagnosis, consult a professional. The most likely diagnosis is Median arcuate ligament syndrome (MALS). Here's why: * Severe epigastric pain worse postprandially: This is a hallmark symptom of MALS. The pain occurs after eating because the stomach and intestines require more blood flow for digestion. In MALS, the median arcuate ligament compresses the celiac artery (which supplies blood to these organs) during exhalation, restricting blood flow and causing pain. * Soft, non-tender abdomen with no palpable masses: This suggests that the pain is not due to an acute abdominal issue like appendicitis or bowel obstruction. * Bruit in the epigastrium: A bruit is an abnormal sound heard over an artery, often indicating turbulent blood flow due to a narrowing or blockage. In MALS, the bruit is caused by the compression of the celiac artery. * Normal USS and OGD: These tests rule out gallstones and upper gastrointestinal issues, respectively, further supporting the diagnosis of MALS. Why other options are less likely: * Sphincter of Oddi dysfunction: This condition involves problems with the valve controlling the flow of bile and pancreatic juices into the duodenum. It can cause abdominal pain, but it's less likely to be associated with a bruit. * Irritable bowel syndrome (IBS): IBS is a functional gastrointestinal disorder that causes abdominal pain and changes in bowel habits. However, it typically doesn't present with severe postprandial pain or a bruit. * Mesenteric vein thrombosis: This is a blood clot in the mesenteric vein, which supplies blood to the intestines. It can cause severe abdominal pain, but it's usually associated with other symptoms like fever, nausea, vomiting, and bloody stools. * GORD (Gastro-oesophageal reflux disease): GORD is a condition where stomach acid flows back into the esophagus, causing heartburn and other symptoms. While it can cause epigastric pain, it's not typically associated with a bruit. Important Note: This is a simplified explanation based on the information provided. A definitive diagnosis of MALS often requires further investigations, such as a CT angiogram or mesenteric angiography, to visualize the celiac artery and confirm the compression.

Answer 65

This is for informational purposes only. For medical advice or diagnosis, consult a professional. The most likely diagnosis is Hydatid cyst. Here's why: * Sheep farmer: This occupation puts him at risk for exposure to Echinococcus granulosus, the tapeworm that causes hydatid cysts. Dogs are the definitive hosts, and sheep are common intermediate hosts. * Malaise and right upper quadrant pain: These are common symptoms of hydatid cysts in the liver, which is the most common location for these cysts. * Mild jaundice: This can occur if the cyst compresses or obstructs the bile ducts. * Elevated eosinophil level: This is a characteristic finding in parasitic infections, including hydatid cysts. * Calcified lesion in the right upper quadrant: Hydatid cysts often have calcified walls, which can be seen on abdominal x-rays. Let's look at why the other options are less likely: * Mesenchymal hamartoma: This is a benign liver tumor that typically occurs in young children, not adults. * Clonorchiasis and Fasciolopsiasis: These are parasitic infections that can cause liver and biliary disease, but they are less common in sheep farmers and don't typically present with calcified lesions. * Liver cell adenoma: This is a benign liver tumor that can occur in women taking oral contraceptives or anabolic steroids. It's not typically associated with calcified lesions or eosinophilia. Important Note: This is a simplified explanation based on the information provided. A definitive diagnosis of hydatid cyst often requires further investigations, such as an ultrasound or CT scan of the abdomen, and serological tests for Echinococcus antibodies.

Answer 66

This is for informational purposes only. For medical advice or diagnosis, consult a professional. The most likely diagnosis is Adenocarcinoma. Here's why: * Never smoked: Adenocarcinoma is the most common type of lung cancer in non-smokers, accounting for the majority of cases. * Peripherally sited mass: Adenocarcinomas often arise in the outer regions of the lung, making them more likely to present as peripheral masses. Let's look at why the other options are less likely: * Small cell lung cancer: This type of lung cancer is strongly associated with smoking and typically presents as a centrally located mass. * Gastric cancer metastasis: While gastric cancer can metastasize to the lungs, it's less likely to present as a solitary peripheral mass. Metastatic lung lesions are often multiple and located in the lower lobes. * Squamous cell carcinoma: This type of lung cancer is also more strongly associated with smoking and tends to arise in the central airways of the lung. * Lymphoma: While lymphoma can affect the lungs, it usually presents with more diffuse infiltrates or multiple nodules rather than a solitary peripheral mass. Important Note: This is a simplified explanation based on the information provided. A definitive diagnosis of lung cancer requires a biopsy or surgical resection of the mass for pathological examination.

Answer 67

This is for informational purposes only. For medical advice or diagnosis, consult a professional. The tumor type found most frequently in a person with aggressive fibromatosis is Desmoid tumors. Here's why: * Desmoid tumors are actually another name for aggressive fibromatosis. They are benign but locally aggressive tumors that arise from connective tissue. Let's look at why the other options are less likely: * Medullary thyroid cancer: This is a type of thyroid cancer that arises from C cells, which produce calcitonin. It's not associated with aggressive fibromatosis. * Basal cell carcinoma of the skin: This is the most common type of skin cancer and is typically caused by sun exposure. It's not related to aggressive fibromatosis. * Dermoid tumors: These are benign tumors that typically occur in the ovaries or testicles. They are not associated with aggressive fibromatosis. * Malignant melanoma: This is a type of skin cancer that arises from melanocytes, the cells that produce melanin. It's not related to aggressive fibromatosis. Important Note: This is a simplified explanation based on the information provided. A definitive diagnosis of aggressive fibromatosis requires a biopsy or surgical resection of the tumor for pathological examination.

Answer 68

The correct answer is Formation of autoantibodies against cell surface antigens. Here's why: * Type II hypersensitivity reactions are characterized by the formation of antibodies (usually IgG or IgM) that bind to antigens on the surface of cells. In the case of autoimmune hemolytic anemia, these antibodies are directed against the individual's own red blood cell antigens (hence, "autoantibodies"). This antibody binding leads to: * Complement activation: The complement system is triggered, leading to the destruction of the red blood cells (hemolysis). * Antibody-dependent cell-mediated cytotoxicity (ADCC): Immune cells (like macrophages and natural killer cells) with receptors for the antibody bind to the antibody-coated red blood cells and kill them. Let's look at why the other options are less likely: * Deposition of immune complexes (Type III hypersensitivity): This involves the formation of antigen-antibody complexes that circulate in the blood and deposit in tissues, causing inflammation. While immune complexes can sometimes be involved in hemolytic anemia, the primary mechanism in autoimmune hemolytic anemia is autoantibody formation. * Cell-mediated immune response (Type IV hypersensitivity): This involves T cells directly attacking target cells. While T cells can play a role in some hemolytic anemias, the classic mechanism of autoimmune hemolytic anemia is antibody-mediated (Type II). * IgE-mediated response (Type I hypersensitivity): This involves IgE antibodies binding to mast cells, which then release histamine and other inflammatory mediators upon encountering the antigen. This is typically associated with allergic reactions, not autoimmune hemolytic anemia.

Answer 69

The most likely underlying cause of linear, branching microcalcifications with coarse granules on a mammogram is Cribriform type ductal carcinoma in situ (DCIS). Here's why: * Cribriform DCIS: This type of DCIS often presents with linear or branching microcalcifications, which correspond to the calcifications within the abnormal ducts. The "coarse granules" description further supports this, as it reflects the irregular calcifications within the cribriform (sieve-like) pattern of the cancerous cells. Let's look at why the other options are less likely: * Invasive lobular carcinoma (ILC): ILC often presents with more subtle mammographic findings, sometimes with architectural distortion or a vague mass. Microcalcifications are not as typical a feature as with DCIS. * Lobular carcinoma in situ (LCIS): LCIS is usually an incidental finding and often does not produce mammographic abnormalities like microcalcifications. It's more often detected through biopsy of an area suspicious for other reasons. * Comedo type ductal carcinoma in situ (DCIS): Comedo DCIS is also associated with microcalcifications, but they tend to be more clustered and linear, often described as "casting" or "rod-like," reflecting the necrotic debris within the ducts. It's less likely to be described as having "coarse granules." * Fibroadenosis: This is a common benign breast condition. While it can sometimes cause microcalcifications, they are usually more scattered and less likely to have the linear, branching pattern with coarse granules seen in cribriform DCIS. Important Note: While cribriform DCIS is the most likely diagnosis given the mammographic description, a definitive diagnosis requires a biopsy and histological examination of the breast tissue. Mammographic features can be suggestive, but they are not always specific.

Answer 70

The serum parathyroid hormone (PTH) level falls rapidly after successful removal of a functioning parathyroid adenoma. Typically, the PTH level drops significantly within 10 minutes postoperatively, as the hyperfunctioning gland is no longer secreting excess hormone oai_citation:0‡Endocrine-Pastest.pdf. Thus, the correct answer is: C. 10 minutes.

Answer 71

The superior salivatory nucleus is responsible for parasympathetic innervation to the lacrimal gland, submandibular gland, and sublingual gland via the facial nerve (CN VII). Damage to this nucleus can lead to impaired lacrimation, resulting in dry cornea. Thus, the correct answer is: A. Superior salivatory nucleus.

Answer 72

The most likely cause of the persistent tenderness 2.5 cm above the joint line on the medial side is an injury to the medial collateral ligament (MCL). The MCL is located on the medial side of the knee, and injury typically occurs due to a direct blow to the lateral side of the knee, causing valgus stress. The presence of an effusion and localized tenderness suggests ligamentous damage rather than an isolated meniscal tear. Correct answer: D. Medial collateral ligament injury.

Answer 73

The most likely diagnosis is osteosarcoma. Explanation: • Osteosarcoma is the most common primary malignant bone tumor in children and adolescents, typically affecting the metaphysis of long bones (e.g., distal femur, proximal tibia). • It is characterized by osteoid formation (bone matrix production). • Common symptoms: Localized bone pain, swelling, and sometimes pathological fractures. • Radiological features: Sunburst appearance and Codman’s triangle on X-ray. Other options: • Ewing sarcoma: Usually affects the diaphysis of long bones and presents with a more systemic illness (fever, leukocytosis). • Chondrosarcoma: More common in older adults and arises from cartilaginous tissue. • Osteoblastoma: A benign tumor that typically occurs in the spine or long bones but is less aggressive. • Benign bone cyst: Fluid-filled lesion, often in younger children, without aggressive features like osteoid formation. Correct answer: A. Osteosarcoma.

Answer 74

The major determinant of cerebral blood flow (CBF) in this scenario is intracranial pressure (ICP). Explanation: • Cerebral blood flow (CBF) is primarily regulated by cerebral perfusion pressure (CPP), which is calculated as: CPP = Mean Arterial Pressure (MAP) - Intracranial Pressure (ICP) • In traumatic brain injury (TBI), increased ICP due to cerebral edema, hemorrhage, or mass effect can reduce CPP, leading to cerebral ischemia. • If ICP increases to the level of MAP, CBF can cease, causing brain herniation and death. • While factors like systemic BP, acidosis, and hypoxemia influence CBF, ICP is the key determinant in a patient with brain injury and raised intracranial pressure. Correct answer: E. Intracranial pressure.

Answer 75

The most appropriate management for a multi-fragmented (comminuted) patellar fracture is wire binding (B. Wire binding), commonly performed using tension band wiring (TBW). Explanation: • Patella fractures can be treated based on the degree of displacement and comminution. • Tension band wiring (TBW) is the preferred technique for comminuted fractures that can still be reconstructed. It converts tensile forces into compressive forces, promoting healing. • Patellectomy (A) is generally reserved for severely comminuted fractures where reconstruction is not possible. • Open reduction and internal fixation (C) is used for displaced transverse fractures but is often supplemented with TBW. • Open reduction and external fixation (D) is not typically used for patellar fractures. • Casting (E) is only suitable for non-displaced fractures. Correct answer: B. Wire binding (Tension Band Wiring).

Answer 76

The structure located behind the 2nd and 3rd parts of the duodenum is the Inferior Vena Cava (IVC) and Aorta. Explanation: • The 2nd part of the duodenum (descending part) runs adjacent to the IVC on its right side. • The 3rd part of the duodenum (horizontal part) crosses anterior to the aorta and IVC. • Other related structures: • Kidney (C) is located posteriorly but laterally, rather than directly behind. • Ureter (A) and Gonadal vessels (B) are also posterior but do not primarily lie behind the duodenum. Correct answer: D. IVC (also, the Aorta is located slightly to the left).

Answer 77

Paget’s disease of the nipple is most strongly associated with ductal carcinoma in situ (DCIS). Explanation: • Paget’s disease of the nipple presents with eczema-like changes (redness, scaling, and ulceration) of the nipple and is often associated with underlying breast malignancy. • DCIS (Ductal Carcinoma In Situ) is the most common underlying malignancy, found in 85–95% of cases. • Mechanism: Malignant ductal cells migrate from the underlying DCIS into the epidermis of the nipple. Other options: • Invasive ductal carcinoma (B): Can be present in some cases, but DCIS is more strongly associated. • Invasive lobular carcinoma (A) & LCIS (D): These typically do not involve the nipple. • Inflammatory breast carcinoma (E): Causes skin thickening and peau d’orange but is not directly linked to Paget’s disease. Correct answer: C. DCIS (Ductal Carcinoma In Situ).

Answer 78

The most likely pathological process in this scenario is colliquative necrosis (liquefactive necrosis). Explanation: • The patient, an elderly woman with a fractured neck of femur, has developed dense hemiparesis postoperatively, suggesting a stroke. • MRI shows a 3 cm area of devitalized tissue in the right frontal lobe, which is characteristic of an ischemic stroke leading to brain infarction. • In the brain, ischemic injury results in liquefactive necrosis (colliquative necrosis) rather than coagulative necrosis, due to the high lipid content and action of hydrolytic enzymes breaking down the tissue into a cystic cavity. Other options: • Coagulative necrosis: Typical of ischemia in solid organs like the heart and kidneys, but not the brain. • Caseous necrosis: Seen in tuberculosis, not stroke. • Fibrinoid necrosis: Found in vasculitis or severe hypertension, not brain infarction. • Apoptosis: A regulated process of programmed cell death, not the main mechanism in ischemic stroke. Correct answer: B. Colliquative necrosis (Liquefactive necrosis).

Answer 79

The correct answer is: B. Stipple cells Explanation: After splenectomy, the spleen’s filtering function is lost, leading to the presence of abnormal red blood cell inclusions in the peripheral blood. The following are typically seen on a blood film post-splenectomy: 1. Howell-Jolly bodies – Small nuclear remnants normally removed by the spleen. 2. Pappenheimer bodies – Iron-containing granules in RBCs. 3. Erythrocytes containing siderotic granules – RBCs with iron deposits, similar to Pappenheimer bodies. 4. Target cells – RBCs with a bullseye appearance due to altered membrane structure. However, stipple cells (basophilic stippling) are associated with lead poisoning, thalassemia, and megaloblastic anemia, not specifically with splenectomy. Correct answer: B. Stipple cells

Answer 80

The best course of action is USS in 3 months Here's why: * AAA repair during next 48 hours: This is too aggressive for a 4.5cm AAA. Surgery is generally recommended for aneurysms larger than 5.5cm or those that are rapidly growing or causing symptoms. * CT aortic angiogram: While CTAs are useful for detailed imaging, they are not the first-line investigation for a 4.5cm AAA. Ultrasound is sufficient for initial assessment and surveillance. * MRI aortic angiogram: MRI is not typically used for AAA surveillance due to cost and availability. * Discharge from the programme: This is not appropriate as the patient has an AAA that requires ongoing monitoring. Surveillance: * Ultrasound is the preferred method for monitoring AAA size. * Repeat ultrasound in 3 months is recommended to assess for growth. * If the aneurysm grows or becomes symptomatic, further investigation and intervention may be necessary.

Answer 81

This is for informational purposes only. For medical advice or diagnosis, consult a professional. The best answer is Loss of elastic fibres from the media. Here's why: * Media: The tunica media is the middle layer of the arterial wall, composed primarily of elastic fibers and smooth muscle cells. These elastic fibers are crucial for the aorta's ability to expand and recoil with each heartbeat, maintaining blood pressure and flow. * Elastic fibers: These fibers provide the aorta with its elasticity and resilience. Their loss leads to weakening of the aortic wall and progressive dilation, which is the hallmark of an abdominal aortic aneurysm (AAA). Other options: * Adventitia: The adventitia is the outermost layer of the arterial wall, composed mainly of collagen and fibroblasts. While it provides structural support, it's not the primary site of initial pathological changes in AAA. * Collagen: Collagen provides tensile strength to the arterial wall. While collagen loss does occur in AAA, it's a later stage process, not the initial event. * Matrix metalloproteinases (MMPs): MMPs are enzymes that degrade the extracellular matrix, including elastin and collagen. Increased MMP activity contributes to AAA development, but it's not the primary pathological explanation for the initial process.

Answer 82

The most likely diagnosis is Anaplastic carcinoma. Here's why: * Rapid Growth and Invasion: Anaplastic carcinoma is a highly aggressive and undifferentiated thyroid cancer known for its rapid growth and local invasion. The description of a "locally infiltrative lesion arising from the thyroid and invading the strap muscles" strongly suggests this characteristic. * Symptoms: The presence of both dysphagia (difficulty swallowing) and dyspnea (difficulty breathing) indicates that the mass is compressing or invading nearby structures, such as the esophagus and trachea. This is consistent with the aggressive nature of anaplastic carcinoma. * Age: While anaplastic carcinoma can occur at any age, it is more common in older individuals, such as this 78-year-old patient. Why other options are less likely: * Lymphoma: Thyroid lymphoma is less common than anaplastic carcinoma and often presents with more generalized lymphadenopathy. * Follicular carcinoma: Follicular carcinoma is usually slow-growing and less likely to cause compressive symptoms like dysphagia and dyspnea unless it is a large, neglected tumor. * Multinodular goitre: While multinodular goiters can grow large and cause compressive symptoms, they are typically benign and do not exhibit the rapid invasion described in this case. * Papillary carcinoma: Papillary carcinoma is the most common type of thyroid cancer, but it is generally slow-growing and less likely to present with rapidly progressive compressive symptoms. Important Note: A definitive diagnosis requires a biopsy and histopathological examination of the lesion.

Answer 83

This is for informational purposes only. For medical advice or diagnosis, consult a professional. The most radiodense renal stone type on a plain x-ray is Calcium oxalate. Here's why: * Calcium oxalate: These stones are composed of calcium oxalate crystals, which are highly dense and readily absorb x-rays. This makes them appear bright white on a plain x-ray. * Calcium phosphate: While also containing calcium, calcium phosphate stones are generally less dense than calcium oxalate stones and may appear slightly less bright on x-ray. * Uric acid: Uric acid stones are radiolucent, meaning they do not show up well on plain x-ray. They can sometimes be visualized on ultrasound or CT scan. * Struvite: Struvite stones, composed of magnesium ammonium phosphate, have moderate radiodensity. They are often associated with urinary tract infections. * Cystine: Cystine stones, formed from the amino acid cystine, have variable radiodensity. They may be faintly visible on plain x-ray. Key takeaway: Calcium oxalate stones are the most common type of renal stone and are also the most radiodense, making them easily detectable on plain x-ray.

Answer 84

The most likely cause is Transitional cell carcinoma (TCC), also known as urothelial carcinoma. Here's why: * Haematuria (recurrent): Painless haematuria is the most common presenting symptom of TCC. * Multiple ureteric filling defects and irregular renal pelvis: These findings on a retrograde pyelogram are highly suggestive of TCC. TCC can occur anywhere in the urothelium, from the renal pelvis down to the bladder. The filling defects represent the tumor within the ureter or renal pelvis, and the irregularity suggests involvement of the lining of the renal pelvis. Why other options are less likely: * Squamous cell carcinoma of the renal pelvis: While squamous cell carcinoma can occur in the renal pelvis, it's less common than TCC and is often associated with chronic irritation or infection. It wouldn't typically present with multiple filling defects. * Adenocarcinoma of the kidney (Renal cell carcinoma - RCC): RCC typically presents as a solitary mass within the kidney itself, not as multiple filling defects in the ureters and renal pelvis. While haematuria can be a symptom, the pyelogram findings are not typical for RCC. * Retroperitoneal sarcoma: These are rare tumors that arise in the retroperitoneum (the area behind the abdominal cavity). They are unlikely to cause the specific pyelogram findings described. They usually present as a palpable mass. * Retroperitoneal fibrosis: This is a rare condition characterized by the formation of fibrous tissue in the retroperitoneum. It can cause ureteric obstruction, but it typically presents with smooth narrowing or obstruction of the ureters, not multiple filling defects. In summary: The combination of recurrent haematuria and the specific findings on the retrograde pyelogram strongly points to transitional cell carcinoma as the most likely diagnosis.

Answer 85

The most likely diagnosis is Torsion of the testis. Here's why: * Sudden onset of pain: Testicular torsion typically presents with sudden, severe pain in the scrotum. * No other urinary symptoms: While urinary symptoms can sometimes accompany other scrotal conditions, their absence is more suggestive of torsion. * Tender superior pole of the testis: This is a key finding in torsion. The tenderness is localized to the area where the spermatic cord is twisted. * Marked cremasteric reflex: While the cremasteric reflex can be variable in torsion, a present or even exaggerated reflex doesn't rule it out. The absence of the reflex is more concerning, but its presence doesn't exclude torsion. The key here is the tenderness at the superior pole. Why other options are less likely: * Epididymo-orchitis: This usually presents with more gradual onset of pain, swelling, and redness of the scrotum. Urinary symptoms are often present. The tenderness would typically be more diffuse, not just at the superior pole. * Torsion of a testicular hydatid: This can also cause sudden scrotal pain, but the tenderness is usually localized to the appendix testis (a small appendage on the testis), not the superior pole. * Viral orchitis: This is more commonly associated with mumps and typically presents with bilateral testicular swelling and tenderness. * Testicular malignancy: Testicular cancer is usually painless and presents as a firm, non-tender mass in the testis. Key point: Testicular torsion is a surgical emergency. Prompt diagnosis and treatment are crucial to salvage the testicle. The history and exam findings are highly suggestive, and immediate surgical consultation is warranted.

Answer 86

The best management is a Suprapubic catheter. Here's why: * Suspected Urethral Injury: The combination of a pelvic fracture, lower abdominal pain, a distended tender bladder, and blood at the urethral meatus strongly suggests a urethral injury. Attempting to pass a urethral catheter in this situation is contraindicated as it can worsen the injury and cause further damage. * Suprapubic Catheter as the Safest Option: A suprapubic catheter is inserted directly into the bladder through a small incision in the abdomen, bypassing the urethra altogether. This is the safest way to drain the bladder in the presence of a suspected urethral injury. Why other options are incorrect: * 10 Ch, 16 Ch, or 18 Ch Foley Urethral Catheter: As mentioned above, passing a urethral catheter is contraindicated in suspected urethral injuries. The size of the catheter is irrelevant in this context. * 18 Ch Coude Tip Urethral Catheter: A coude tip catheter is designed to navigate bends in the urethra, but it's still a urethral catheter and therefore contraindicated. * Pain relief and review in 1 hour: Delaying intervention in this scenario is dangerous. A distended bladder can cause significant discomfort and potentially lead to further complications. Immediate bladder drainage is necessary. In summary: In a patient with a pelvic fracture, signs of a potential urethral injury, and a distended bladder, the priority is to avoid urethral catheterization and establish bladder drainage via a suprapubic catheter. This should be done in consultation with a urologist.

Answer 87

The most likely diagnosis is Renal adenocarcinoma (Renal Cell Carcinoma - RCC). Here's why: * Classic Triad: The combination of haematuria, flank pain (represented by the loin mass), and a palpable abdominal mass is the classic triad of symptoms for renal cell carcinoma. While not all patients present with all three, their presence together is highly suggestive. * Other Symptoms: Lethargy and haemoptysis can also be associated with RCC. Lethargy can be due to paraneoplastic syndromes (hormone-like substances produced by the tumor), and haemoptysis can occur if the tumor metastasizes to the lungs. * CT Scan Findings: A lesion in the upper pole of the kidney with a small cystic center is a common appearance of RCC on CT scan. While other kidney lesions can have cystic components, this description fits well with RCC. * Age: RCC is most common in adults, typically between 50 and 70 years old, which aligns with the patient's age. Why other options are less likely: * Squamous cell carcinoma of the kidney: This is a rarer type of kidney cancer and is often associated with chronic kidney stones or infections. It's less likely to present with the classic triad and the described CT findings. * Nephroblastoma (Wilms tumor): This is a childhood cancer, typically presenting in children under the age of 5. It's highly unlikely in a 56-year-old man. * Transitional cell carcinoma of the kidney: This cancer arises from the lining of the renal pelvis and ureters. While it can cause haematuria, it's less likely to present with a loin mass and the specific CT findings described. It would more likely cause filling defects in the renal pelvis/ureter. * Polycystic kidney disease (PKD): PKD is a genetic disorder characterized by multiple cysts throughout both kidneys. While it can cause haematuria and abdominal masses (due to enlarged kidneys), it typically presents with bilateral involvement and wouldn't have a single dominant lesion with a cystic center like described. It also wouldn't typically cause haemoptysis. Therefore, the combination of clinical presentation and CT scan findings makes renal adenocarcinoma the most likely diagnosis in this case.

Answer 88

The most likely stone composition is Struvite. Here's why: * Staghorn Calculus: Staghorn calculi are large stones that fill the renal pelvis and calyces, taking on a branched, "staghorn" shape. They are most commonly composed of struvite. * Recurrent Urinary Tract Sepsis: Struvite stones are often associated with urinary tract infections (UTIs) caused by urease-producing bacteria (such as Proteus species). These bacteria split urea into ammonia, which raises the urinary pH and promotes the precipitation of struvite crystals. The recurrent UTIs in this patient strongly suggest a role for these bacteria and, therefore, struvite stones. * High Urinary pH (7.8): Struvite stones form in alkaline urine (pH > 7.0). A urinary pH of 7.8 is consistent with struvite stone formation. * Faint Outline on KUB X-ray: Struvite stones have a relatively low density compared to calcium oxalate stones and may appear fainter on plain x-ray. Why other options are less likely: * Calcium phosphate: While calcium phosphate stones can also form in alkaline urine, they are less commonly associated with staghorn calculi and recurrent UTIs. * Calcium oxalate: Calcium oxalate stones are the most common type of kidney stones overall, but they typically form in acidic or neutral urine and are not associated with urease-producing bacteria. They are also usually more radiopaque (denser) on x-ray. * Uric acid: Uric acid stones form in acidic urine and are radiolucent (not visible) on plain x-ray. * Cystine: Cystine stones are associated with a genetic disorder and are not typically associated with recurrent UTIs or a high urinary pH. They can be faintly visible on x-ray, but the clinical picture is more suggestive of struvite. In summary: The combination of a staghorn calculus, recurrent UTIs, and a high urinary pH strongly points towards struvite as the most likely stone composition.

Answer 89

The most likely diagnosis is Classical seminoma. Here's why: * Painless Swelling: Painless testicular swelling is a common presentation of testicular cancer. * Lymphocytic Infiltrate: A prominent lymphocytic infiltrate within the stroma is a characteristic feature of classical seminoma. This is a key histological finding that distinguishes it from other types of testicular tumors. * Age: Seminoma is the most common type of testicular cancer, and it typically occurs in men aged 20-40, which aligns with the patient's age. Why other options are less likely: * Differentiated teratoma: Teratomas contain various differentiated tissues (e.g., hair, teeth, skin). While they can be benign or malignant, they don't typically have the prominent lymphocytic infiltrate seen in seminomas. * Malignant undifferentiated teratoma: Similar to differentiated teratomas, undifferentiated teratomas don't characteristically have the dense lymphocytic infiltrate. * Spermatocytic seminoma: This is a less common variant of seminoma that usually occurs in older men (over 50) and has a different histological appearance (smaller cells, no lymphocytic infiltrate). * Anaplastic seminoma: This is a more aggressive variant of seminoma, but the key distinguishing feature remains the prominent lymphocytic infiltrate, which is seen in both classical and anaplastic seminomas. Since "classical" is an option and is more common, it's the better answer. Anaplastic would be considered if the question stem mentioned features of rapid growth or spread. Therefore, the combination of painless swelling, lymphocytic infiltrate, and the patient's age strongly suggests classical seminoma as the most likely diagnosis.

Answer 90

The most likely diagnosis is Sperm granuloma. Here's why: * Location: The nodule is described as being adjacent to the vas, which is the location where a sperm granuloma is most likely to occur after a vasectomy. * Mechanism: A sperm granuloma forms when sperm leaks from the cut end of the vas deferens and elicits an inflammatory response. It's essentially a reaction to the leaked sperm. * Timing: It's common to find these after a vasectomy, as this disrupts the normal flow of sperm. * Appearance: They are typically small, firm nodules. Why other options are less likely: * Haematoma: While a hematoma (collection of blood) can occur after any surgical procedure, it would usually be more diffuse and would likely resolve over time. It wouldn't typically persist as a small, rounded nodule. * Varicocele: A varicocele is an enlargement of the veins within the scrotum. It feels like a "bag of worms" and is located above and behind the testicle, not specifically adjacent to the vas. * Hydrocele: A hydrocele is a collection of fluid around the testicle, causing scrotal swelling. It wouldn't present as a small, rounded nodule adjacent to the vas. * Epididymal cyst: These are fluid-filled cysts within the epididymis (a structure behind the testicle). They are usually located away from the vas deferens, though close by, and are typically smooth and mobile. In summary: A small, rounded nodule adjacent to the vas deferens after a vasectomy is most consistent with a sperm granuloma.

Answer 91

The most likely organism is Proteus mirabilis. Here's why: * Staghorn Calculus: Staghorn calculi, as mentioned before, are large stones that fill the renal pelvis and calyces. They are strongly associated with Proteus mirabilis infections. * Urease Production: Proteus mirabilis is a urease-producing organism. Urease breaks down urea into ammonia, which alkalinizes the urine. This alkaline environment favors the formation of struvite stones, which are the most common component of staghorn calculi. * Recurrent Loin Pain and Fevers: These symptoms suggest recurrent urinary tract infections (UTIs), which are common with struvite stones and Proteus infections. Why other options are less likely: * Staphylococcus saprophyticus: While S. saprophyticus is a common cause of UTIs, particularly in young women, it's not typically associated with staghorn calculi formation. * Klebsiella: Klebsiella can cause UTIs, but it's less strongly associated with staghorn calculi compared to Proteus. * E. coli: E. coli is the most common cause of UTIs overall, but it's less likely to produce staghorn calculi unless there is some other complicating factor. * Staphylococcus epidermidis: S. epidermidis is more commonly associated with infections of indwelling medical devices (like catheters) and is less likely to cause staghorn calculi. Key takeaway: The combination of a staghorn calculus, recurrent loin pain and fevers (suggestive of recurrent UTIs), and the known association of Proteus mirabilis with struvite stones makes Proteus the most likely causative organism.

Answer 92

Phosphaturia does not cause red urine. It can make urine appear cloudy or milky, but it doesn't change the color to red. The others can cause red urine: * Rifampicin: This antibiotic can turn urine (and other bodily fluids) reddish-orange. * Beetroot: Eating beetroot can cause red or pink urine (beeturia) in some people. * Rhubarb: Rhubarb can also cause red or pink urine. * Blackberries: Eating a large quantity of blackberries can sometimes lead to red or purplish discoloration of the urine.

Answer 93

The best course of action is Testicular USS (ultrasound). Here's why: * Need for Assessment: The patient has sustained trauma to the scrotum, and you can't adequately examine the testis due to swelling. You need to know what's going on inside. Ultrasound is the best way to do this. * What Ultrasound Will Show: The ultrasound will help determine if there is: * Testicular rupture: This is a surgical emergency. * Hematocele: A collection of blood around the testis. * Testicular torsion: Twisting of the spermatic cord, also a surgical emergency. * Other injuries: Such as epididymitis or soft tissue injury. * Guiding Further Management: The ultrasound findings will dictate the next steps. If there's a rupture or torsion, surgery (exploration and likely repair/orchidectomy) will be needed urgently. If it's a hematocele or other less serious injury, conservative management might be appropriate. Why other options are not the best initial course of action: * Inguinal orchidectomy/Scrotal orchidectomy: These are treatment options, not diagnostic ones. You don't know yet if the testis needs to be removed. Orchidectomy would only be considered if the testis is non-viable (e.g., due to severe trauma or torsion). * Scrotal exploration: Surgery without knowing what you're dealing with is not the best approach. Ultrasound is non-invasive and provides valuable information that will guide surgical decisions, if surgery is even needed. Going straight to exploration could potentially cause more harm. In short: Ultrasound is the essential first step to assess the extent of the injury and determine the appropriate treatment.

Answer 94

The most likely cause is Polycystic kidney disease (PKD). Here's why: * Family History: The sister's subarachnoid hemorrhage raises a strong suspicion for PKD. PKD is a hereditary condition, and the most common type (autosomal dominant PKD) often presents with kidney cysts and can also be associated with intracranial aneurysms (which can lead to subarachnoid hemorrhage). * Painless Haematuria: Painless haematuria is a common symptom of PKD. The bleeding is usually microscopic, but it can sometimes be visible (gross haematuria). * Mild Renal Impairment: PKD is a progressive condition that can lead to chronic kidney disease and renal impairment. Why other options are less likely: * Adenocarcinoma of the bladder/Renal cancer: While these cancers can cause haematuria, they are less likely to be associated with a family history of subarachnoid hemorrhage. Renal cell carcinoma typically presents as a solitary mass, not with the diffuse cystic changes of PKD. Bladder cancer would not cause renal impairment. * Bladder stones: Bladder stones can cause haematuria, but they are usually associated with other symptoms like pain, dysuria (painful urination), and urgency. Also, they would not explain the renal impairment. * Pyelonephritis: Pyelonephritis (kidney infection) usually presents with fever, flank pain, and other signs of infection. While it can cause haematuria, the lack of these symptoms makes it less likely. It would not explain the family history. Key takeaway: The combination of painless haematuria, mild renal impairment, and a strong family history of subarachnoid hemorrhage (suggestive of PKD) makes PKD the most likely diagnosis. Further investigation, such as a renal ultrasound or CT scan, would be needed to confirm the diagnosis.

Answer 95

The most likely diagnosis is Bladder rupture. Here's why: * Pelvic Fracture: Pelvic fractures are commonly associated with bladder injuries. * Lower Abdominal Pain and Peritonism: These signs suggest peritoneal irritation, which is a strong indicator of bladder rupture (urine leaking into the abdominal cavity). Peritonism is a sign of inflammation of the peritoneum (lining of the abdomen) and is characterized by abdominal pain, tenderness, rigidity, and guarding. * No Urine Output: This suggests that urine is not draining from the bladder, which is consistent with a rupture. * Free Fluid on CT Scan: This confirms that there is fluid outside of the bladder, likely urine, which has leaked into the abdomen due to the rupture. Why other options are less likely: * Membranous/Bulbar Urethral Injury: While urethral injuries can occur with pelvic fractures, they wouldn't typically cause peritonism (unless there's also a bladder injury). Urethral injuries would also present with blood at the urethral meatus, which isn't mentioned here. * Bladder Contusion: A contusion is a bruise. While it can cause pain and possibly some blood in the urine (hematuria), it wouldn't lead to free fluid in the abdomen or an inability to pass urine. * Urinary Tract Infection (UTI): A UTI would not be associated with trauma, pelvic fracture, inability to pass urine, free fluid, or peritonism. In summary: The combination of a pelvic fracture, lower abdominal pain with peritonism, no urine output, and free fluid on CT scan strongly points to a bladder rupture. This is a serious injury requiring prompt surgical intervention.

Answer 96

The most likely diagnosis in this case is dislocated patella (option C). Explanation: • The positive patellar tap suggests a significant effusion, indicating intra-articular injury. • Inability to extend the knee suggests disruption of the extensor mechanism, which is commonly seen in patellar dislocations. • Mechanism of injury (twisting) is a classic cause of patellar dislocation, often seen in sports injuries. Why not the other options? • Anterior cruciate ligament (ACL) injury (A): Would present with instability and a positive anterior drawer or Lachman test, but usually allows some degree of extension. • Knee dislocation (B): A much more severe injury that typically involves multiple ligament ruptures and potential neurovascular compromise. • Bucket handle meniscal tear (D): Can cause locking of the knee but does not typically cause an effusion large enough for a positive patellar tap. • Lateral collateral ligament injury (E): Would not explain the large effusion or inability to extend the knee. This matches findings from MRCS recall questions, where dislocated patella is often associated with acute swelling and inability to extend the knee oai_citation:0‡MCQs_for_the_MRCS_Part_A.pdf.

Answer 97

The most likely diagnosis in this case is Aortic dissection (option A). Explanation: • Tall patient: This could indicate Marfan syndrome or another connective tissue disorder, which increases the risk of aortic dissection. • Sudden sharp abdominal pain radiating to the groin: Aortic dissection can extend along the aorta and cause pain radiating to different regions, including the abdomen and groin. • History of chest pain and TIA: • Chest pain is a classic symptom of aortic dissection, often described as tearing or ripping. • TIA (Transient Ischemic Attack): Suggests prior arterial embolization, which can be a complication of dissection if it affects blood flow to the brain. Why not the other options? • Pulmonary embolism (B): Typically presents with pleuritic chest pain, shortness of breath, and hypoxia, but not abdominal pain radiating to the groin. • Myocardial infarction (C): Causes chest pain but does not typically present with groin pain or a history of TIA. • Ruptured abdominal aortic aneurysm (D): Can cause sudden abdominal pain but is more common in elderly male smokers and presents with hypotension and shock. • Perforated abdominal viscus (E): Causes generalized peritonitis with fever and guarding, but does not explain the patient’s history of TIA and chest pain. Takeaway: Aortic dissection should be suspected in tall patients with sudden sharp pain (often tearing in nature) radiating along the aorta and a history suggestive of connective tissue disorders or arterial embolization. Immediate CT angiography or transesophageal echocardiography is needed for diagnosis.

Answer 98

The best next definitive investigation in this case is MRI (option B). Explanation: • Mechanism of injury (direct trauma with a hockey stick) suggests a soft tissue injury rather than a fracture. • Tense and swollen knee indicates a hemarthrosis (blood in the joint), which is often seen in ligamentous injuries (ACL tear, PCL tear) or chondral injuries. • X-ray shows no fracture, so a bony injury is ruled out, making soft tissue assessment (ligaments, menisci, cartilage) the priority. Why not the other options? • CT (A): Better for bony injuries, but X-ray already ruled out fractures. • Bone scan (C): Used for stress fractures or infections, which are not suggested by the history. • Aspiration (D): Can confirm hemarthrosis, but does not define the extent of ligament or meniscal damage. • Arthroscopy (E): Invasive and used for treatment rather than initial diagnosis. Takeaway: For a soft tissue knee injury (tense, swollen knee with no fracture on X-ray), MRI is the best next definitive investigation to assess ligaments, menisci, and cartilage damage.

Answer 99

The correct answer is: C. AL amyloidosis Explanation: • Multiple myeloma is strongly associated with AL (Amyloid Light-chain) amyloidosis. • Pink, fleshy lesion is suggestive of amyloid deposition, which can occur in the skin, tongue (macroglossia), or other soft tissues. • AL amyloidosis is caused by the deposition of monoclonal light chains (lambda or kappa) produced by plasma cells, often in the setting of multiple myeloma. Why not the other options? • Metaplasia (A): A reversible change in cell type (e.g., Barrett’s esophagus), not typically associated with multiple myeloma. • Dysplasia (B): Refers to disordered cellular growth, a precancerous change seen in epithelial tissues, not in multiple myeloma. • AA amyloidosis (D): Associated with chronic inflammatory conditions (e.g., rheumatoid arthritis, tuberculosis), not multiple myeloma. • Beta-2 microglobulin amyloidosis (E): Occurs in long-term hemodialysis patients, due to β2-microglobulin accumulation in joints and bones, not soft tissue lesions in multiple myeloma. Takeaway: • AL amyloidosis is the most common type of amyloidosis in multiple myeloma, often presenting with soft tissue deposits, cardiac involvement, nephrotic syndrome, or macroglossia. • Diagnosis is confirmed by Congo red staining with apple-green birefringence under polarized light.

Answer 100

The correct answer is: A. Admit for 6 hours and observe Explanation: • This patient had a brief loss of consciousness (LOC) after a fall, which raises concern for minor traumatic brain injury (TBI) or concussion. • According to NICE guidelines for head injury, patients with a brief LOC but no high-risk features should be observed for at least 6 hours in a medical setting. • Observation helps detect delayed deterioration due to a slowly evolving intracranial hemorrhage (e.g., subdural hematoma). Why not the other options? • Immediate CT (B): Indicated if there are red flag signs such as: • GCS < 13 on initial assessment • Persistent vomiting • Focal neurological deficit • Signs of skull fracture • Post-traumatic seizure • Coagulopathy or age >65 (Since this patient is alert and recovered, an immediate CT is not required.) • CT after 1 hour (C): There is no guideline recommending a 1-hour delay; observation is the correct approach unless high-risk features develop. • Call a neurosurgeon (D): Neurosurgical consultation is necessary only if CT shows a significant brain injury requiring intervention. • Discharge and instruct on warning signs (E): While patient education is important, immediate discharge is inappropriate because a delayed bleed (e.g., subdural hematoma) can develop. Takeaway: For a patient with a brief LOC after trauma but no immediate red flags, the correct approach is 6 hours of observation in a medical setting. If symptoms worsen, a **CT

Answer 101

The correct answer is: D. Condyle Explanation: • Fall onto the chin can transmit force to the temporomandibular joint (TMJ) and cause a condylar fracture. • Symptoms suggestive of a condylar fracture: • Teeth become separated → Indicates malocclusion (misalignment of the jaws). • Reduced mouth opening → Suggests involvement of the TMJ. • Tenderness in the pre-auricular area → The condyle is located near the TMJ, making this a key finding. Why not the other options? • Body of the mandible (A): Fractures here cause localized pain and swelling along the jawline, not pre-auricular tenderness or TMJ dysfunction. • Ramus (B): Rarely fractured in isolation and does not cause significant malocclusion or TMJ pain. • Coronoid process (C): Rarely fractures unless due to direct trauma, does not affect occlusion significantly. • Angle of the mandible (E): More commonly fractured by lateral blows, often leading to pain at the fracture site but not TMJ symptoms. Takeaway: A fall onto the chin with pre-auricular tenderness, malalignment, and reduced mouth opening strongly suggests a condylar fracture of the mandible. Panoramic X-ray (OPG) or CT scan can confirm the diagnosis.

Answer 102

The correct answer is: E. True cut biopsy Explanation: • A firm, painless mass in a BRCA1-positive patient is highly suspicious for breast cancer. • True cut biopsy (core needle biopsy) is the best next step because: • It provides histological diagnosis, differentiating between benign and malignant lesions. • It allows for hormone receptor and HER2 status assessment, which is crucial for treatment planning. • It is more accurate than FNAC (fine-needle aspiration cytology), which may not provide sufficient tissue architecture. Why not the other options? • MRI (A): • MRI is the most sensitive imaging modality for BRCA1 carriers but is used for screening and staging rather than as a first-line investigation for a palpable mass. • Ultrasound (B): • Useful in younger women (dense breasts) and to differentiate cystic vs. solid masses but does not confirm malignancy. • Mammography (C): • Important for screening, but in younger patients (<40), breast tissue is dense, limiting sensitivity. • Can be used alongside biopsy but is not the next best step alone. • FNAC (D): • Can confirm malignancy but does not provide tissue architecture for receptor status assessment. • Higher risk of false negatives than core biopsy. Takeaway: In a BRCA1-positive patient with a suspicious breast lump, a true cut biopsy is the next best step to confirm malignancy and guide treatment. Imaging (US/Mammogram/MRI) can be done afterward for staging.

Answer 103

The correct answer is: A. Lymphoma Explanation: • Rapidly enlarging thyroid gland with dysphagia suggests an aggressive thyroid pathology. • History of Hashimoto’s thyroiditis is a major risk factor for primary thyroid lymphoma (PTL). • CD20+ phenotype confirms a B-cell origin, which is characteristic of thyroid lymphoma. • Bland cells suggest a low-grade malignancy, which is typical of MALT lymphoma (a subtype of PTL). Why not the other options? • Medullary thyroid carcinoma (B): • Arises from parafollicular C-cells, not lymphoid tissue. • Associated with calcitonin elevation, not CD20 positivity. • Follicular thyroid carcinoma (C): • More common in iodine-deficient areas and spreads hematogenously. • Does not present with rapid enlargement or CD20 positivity. • Papillary thyroid carcinoma (D): • The most common thyroid cancer but slow-growing. • Shows Orphan Annie nuclei, psammoma bodies, and is not CD20 positive. • Anaplastic carcinoma (E): • Rapidly enlarging and highly aggressive, but typically CD20 negative. • Shows pleomorphic, undifferentiated cells, not bland cells. Takeaway: Primary thyroid lymphoma (PTL) should be suspected in a patient with Hashimoto thyroiditis, a rapidly enlarging thyroid mass, and CD20 positivity. Biopsy confirms the diagnosis, and treatment involves chemotherapy and radiation, not surgery.

Answer 104

The correct answer is: D. Carbimazole Explanation: • Graves’ disease is an autoimmune hyperthyroidism often treated initially with antithyroid drugs (ATDs) like carbimazole or propylthiouracil (PTU). • Relapse after 12 months suggests persistent disease, and the usual next step is to restart antithyroid medication or consider definitive treatment (radioactive iodine or surgery). • Carbimazole is preferred over PTU due to better safety profile and once-daily dosing. Why not the other options? • Propylthiouracil (A): • Used in pregnancy (first trimester) or in thyroid storm, but not the first choice due to risk of hepatotoxicity. • Propranolol (B): • Beta-blockers relieve symptoms (tachycardia, tremors) but do not treat the underlying cause. • Steroids (C): • Used in thyroid eye disease, not for relapse of hyperthyroidism. • Thyroxine (E): • Used in hypothyroidism, not hyperthyroidism. Takeaway: For a Graves’ disease relapse, the first step is to restart carbimazole. If relapse happens again after prolonged treatment, consider radioactive iodine or thyroidectomy for definitive management.

Answer 105

The correct answer is: C. ACL tear (Anterior Cruciate Ligament tear) Explanation: • Mechanism of injury: A 19-year-old skier suggests a non-contact twisting injury, common in ACL tears. • Severe pain and immediate swelling: • Instant swelling (hemarthrosis) is highly suggestive of an ACL tear due to the vascular supply of the ACL. • Other causes of hemarthrosis: Patellar dislocation, tibial plateau fracture, or PCL injury. • Aspiration shows large hemarthrosis: • ACL tears cause 70-80% of acute traumatic hemarthroses in young athletes. • Meniscal and collateral ligament injuries do not typically cause immediate large effusions. Why not the other options? • Patellar tendon rupture (A): • Causes inability to extend the knee, but does not usually lead to large hemarthrosis. • Meniscal damage (B): • Causes delayed swelling (over 24 hours) due to synovial fluid accumulation, not hemarthrosis. • PCL tear (D): • Often caused by a direct blow to the anterior tibia (dashboard injury) rather than a twisting mechanism. • Hemarthrosis can occur but is less common than in ACL injuries. • Medial collateral ligament (MCL) injury (E): • Causes localized medial pain and valgus instability, but does not cause significant hemarthrosis. Takeaway: A young athlete with a twisting knee injury, immediate swelling, and hemarthrosis likely has an ACL tear. Diagnosis is confirmed with Lachman test, anterior drawer test, and MRI.

Answer 106

The answer is C. The membranous urethra is ruptured. Here's why: * High-riding prostate: A high-riding or non-palpable prostate on rectal exam in the context of pelvic fracture and hypovolemic shock is a strong indicator of posterior urethral injury. This typically involves the membranous urethra. The prostate is displaced superiorly by the pelvic fracture fragments. * Membranous vs. Bulbar Urethra: The bulbar urethra is more anterior and injuries to it are less likely to cause a high-riding prostate. Bulbar urethral injuries are more commonly associated with straddle injuries. * Bladder Rupture: While bladder rupture can occur with pelvic fractures, it doesn't directly cause a high-riding prostate. Bladder injuries are often diagnosed with cystography. * Prostatic Urethra: Prostatic urethral injuries are less common than membranous urethral injuries in pelvic fractures. They might also present with a high-riding prostate, but the membranous urethra is more frequently involved. Therefore, the most likely cause given the presented scenario is a ruptured membranous urethra.

Answer 107

The best next step is D. Intracavernous injection. Here's the reasoning: * Aspiration Failure: The patient has already undergone aspiration without improvement. This indicates a more persistent and likely higher-flow priapism. * Intracavernosal Injection: This is the next line of treatment for priapism that fails aspiration. It typically involves injecting a sympathomimetic agent like phenylephrine directly into the corpora cavernosa. This constricts the penile arteries, reducing blood flow and hopefully resolving the priapism. * Phenylephrine Systemically: While phenylephrine is used, it's more effective when injected directly into the corpora cavernosa. Systemic administration isn't as targeted and may have more side effects. * Surgical Exploration: Surgery is usually reserved for refractory cases of priapism that fail all other treatments. It's a more invasive procedure and not the next best step after failed aspiration. * Analgesia and Follow-up: While pain management is important, simply providing analgesia and following up without attempting to actively resolve the priapism is not appropriate. Prolonged priapism can lead to significant complications, including erectile dysfunction. Active intervention is required. Therefore, intracavernous injection is the most appropriate next step after aspiration has failed in this patient with sickle cell-related priapism.

Answer 108

The best initial management option is A. Intracavernosal aspiration. Here's the breakdown: * SSRI-Associated Priapism: Priapism is a known, though rare, side effect of SSRIs. While the exact mechanism isn't fully understood, it's thought to involve changes in neurotransmitter levels. * Initial Management: The first-line treatment for priapism, regardless of the cause, is typically intracavernosal aspiration. This involves inserting a needle into the corpora cavernosa and draining the trapped blood. This can often relieve the pressure and resolve the priapism. * Other Options: * Analgesia: While pain management is important, it doesn't address the underlying issue of the priapism itself. Aspiration is the priority. * Surgical Shunting: This is a more invasive procedure reserved for cases of priapism that are refractory to other treatments. It's not a first-line option. * Phenylephrine: While phenylephrine (or other alpha-adrenergic agonists) can be used, it's usually the next step if aspiration is unsuccessful. Aspiration is simpler and less invasive as a first attempt. * Intracavernous Injection: This refers to injecting medications (like phenylephrine) into the corpora cavernosa. While this is a valid treatment, aspiration is generally tried first. Therefore, intracavernosal aspiration is the most appropriate initial management option for this patient with SSRI-associated priapism.

Answer 109

The most appropriate next step in the management of this patient's pain is b. Nerve block (e.g., celiac plexus block). Here's why: * Chronic Pancreatitis Pain: Chronic pancreatitis often causes severe, debilitating pain that is difficult to manage. It's characterized by inflammation and damage to the pancreas, leading to both abdominal and back pain (due to the pancreas's retroperitoneal location). * Why not the other options? * NSAIDs: While NSAIDs might be used for mild pain, they are unlikely to provide sufficient relief for the severe, persistent pain described in this case. Long-term NSAID use also carries risks, especially in patients with chronic conditions. * Opioids: Opioids can be effective for pain management, but they are generally not the first-line treatment for chronic pancreatitis pain due to the risks of dependence, tolerance, and other side effects. They might be considered if other options fail. * PERT Adjustment: While pancreatic enzyme replacement therapy (PERT) is crucial for managing maldigestion and malabsorption in chronic pancreatitis, it primarily addresses those issues, not directly the pain itself. It's an important part of the overall management but not the most appropriate next step for pain relief. * ERCP with Sphincterotomy: ERCP is a procedure used to visualize and treat the pancreatic and bile ducts. While it can be helpful in certain situations (e.g., strictures, stones), it's not the primary approach for managing chronic pancreatitis pain. It's more invasive and carries its own risks. * Celiac Plexus Block: A celiac plexus block involves injecting local anesthetic into the celiac plexus, a network of nerves that innervates the upper abdominal organs, including the pancreas. This can provide significant pain relief for some patients with chronic pancreatitis. It's a less invasive procedure than surgery and can be repeated if necessary. It is often considered before moving on to stronger pain medications like opioids.

Answer 110

This medical question appears to be testing knowledge about differentiating between prerenal and intrinsic renal failure in a patient with oliguria. To solve this, I need to analyze each option and determine which finding would be characteristic of a patient who remains oliguric after adequate fluid resuscitation. Let's analyze each option: A. Urine to plasma osmolarity ratio 1:1 In prerenal azotemia, this ratio would typically be >1.5:1 as the kidneys try to conserve water. A ratio of 1:1 suggests the kidneys have lost concentrating ability, indicating acute tubular necrosis (ATN) or intrinsic renal failure. B. Urine specific gravity 1010 Normal urine specific gravity ranges from 1.003-1.030. A fixed specific gravity around 1.010 (isosthenuric) indicates loss of concentrating ability, consistent with ATN. C. Urine osmolarity 250 Normal urine osmolarity ranges from 300-900 mOsm/L. A value of 250 mOsm/L (close to plasma osmolarity) indicates loss of concentrating ability, consistent with ATN. D. Urine sodium 10 In prerenal azotemia, urine sodium is typically <20 mEq/L as the kidneys try to conserve sodium. A value of 10 mEq/L suggests prerenal causes rather than intrinsic renal failure. E. All of the above Since the patient remains oliguric after fluid challenge, this suggests progression from prerenal to intrinsic renal failure (likely ATN). The characteristic findings would be: - Urine:plasma osmolarity ratio close to 1:1 - Fixed urine specific gravity around 1.010 - Urine osmolarity close to plasma (around 250-300) - Urine sodium typically >20 mEq/L in ATN Since option D (urine sodium 10) is more consistent with prerenal failure rather than intrinsic renal failure after fluid challenge, not all findings listed are characteristic. The answer is not E. The most likely answer is A, as a urine to plasma osmolarity ratio of 1:1 is highly characteristic of intrinsic renal failure when a patient remains oliguric after fluid challenge.

Answer 111

The patient's presentation is concerning for a **pulmonary embolism (PE)**. Here's why: 1. **History**: The patient was in a road traffic accident (RTA) and sustained fractures of ribs 5 and 6. This immobility and trauma increase the risk of deep vein thrombosis (DVT) and subsequent PE. 2. **Timing**: The onset of dyspnea and other symptoms 3 days after the injury is consistent with the timeline for PE development. 3. **Symptoms**: Dyspnea, tachycardia (HR 90), and sweating are classic signs of PE. 4. **Examination**: Poor air entry without abnormal sounds (e.g., crackles or wheezes) suggests a ventilation-perfusion mismatch, which is common in PE. 5. **Blood pressure**: The elevated blood pressure (170/9) could be due to pain or stress, but it does not rule out PE. ### Why not the other options? - **A. Ineffective analgesia**: While pain could contribute to tachycardia and hypertension, it does not explain the dyspnea or poor air entry. - **B. Pneumonia**: Pneumonia typically presents with fever, cough, and abnormal lung sounds (e.g., crackles), which are absent here. - **D. ARDS (Acute Respiratory Distress Syndrome)**: ARDS usually develops over hours to days in the setting of severe systemic illness or trauma, but it is less likely in this case without hypoxia or bilateral infiltrates on imaging. - **E. COPD**: COPD exacerbation would typically present with wheezing, prolonged expiration, and a history of chronic lung disease, which is not mentioned here. ### Next steps: - **Immediate investigations**: - Arterial blood gas (ABG) to assess for hypoxia and elevated alveolar-arterial gradient. - CT pulmonary angiogram (CTPA) to confirm PE. - D-dimer (if low clinical probability). - ECG to look for signs of right heart strain (e.g., S1Q3T3 pattern). - **Management**: - Start anticoagulation (e.g., low molecular weight heparin) if PE is suspected. - Oxygen therapy if hypoxic. - Consider thrombolysis if hemodynamically unstable. This patient requires urgent evaluation and treatment for suspected PE.

Answer 112

Let's analyze this case carefully: A 46-year-old woman underwent laparoscopic cholecystectomy for chronic calculous cholecystitis. Three days after surgery, she presents with: - Progressive jaundice - Pale stools - Dark urine These symptoms strongly suggest biliary obstruction. Let's evaluate each option: A. Bile duct injury This is a known complication of laparoscopic cholecystectomy, occurring in 0.3-0.7% of cases. The timing (3 days post-op) and symptoms (jaundice, pale stools, dark urine) are classic for bile duct injury. The pale stools indicate lack of bile reaching the intestine, while dark urine suggests bilirubin being excreted renally instead. B. Collection at the surgical site While a biloma (bile collection) can occur after cholecystectomy, it typically causes pain, fever, and sometimes a palpable mass. It wouldn't typically cause obstructive jaundice with pale stools this quickly unless it was compressing the bile duct externally, which is less common. C. Residual CBD stone Retained stones in the common bile duct are possible, especially with pre-existing gallstones. However, these stones would have been present before surgery. The new onset of complete biliary obstruction symptoms after surgery makes this less likely than bile duct injury. D. Acute pancreatitis Post-ERCP pancreatitis can occur, but post-cholecystectomy pancreatitis typically presents with severe epigastric pain radiating to the back, nausea, vomiting, and elevated lipase/amylase. The clinical picture doesn't suggest pancreatitis as the primary issue. E. Cholangitis Cholangitis typically presents with Charcot's triad (fever, jaundice, right upper quadrant pain) or Reynolds' pentad (plus hypotension and altered mental status). The absence of fever or pain in the case description makes cholangitis less likely. The most probable diagnosis is: A. Bile duct injury This best explains the complete biliary obstruction picture (progressive jaundice, pale stools, dark urine) developing in the days following laparoscopic cholecystectomy. Bile duct injuries often become apparent 1-7 days after surgery as biliary obstruction develops, matching this timeline perfectly.

Answer 113

The most appropriate action in this scenario is: **E. Incident report** ### Explanation: - **Incident report**: If you observe a nurse practicing a minor procedure without evidence or references, it is important to document the incident. This ensures that the situation is formally recorded and can be reviewed by the appropriate authorities within the healthcare facility. Reporting the incident allows for an investigation to determine if there was a breach of protocol and helps prevent future occurrences. ### Why not the other options? - **A. Risk assessment**: While a risk assessment might be part of the follow-up process, it is not the immediate action to take when observing the incident. - **B. Medical audit**: A medical audit is a systematic review of clinical practices, but it is not the immediate response to an observed incident. - **C. Report to GMC**: Reporting to the General Medical Council (GMC) would be premature unless the incident involves a serious breach of professional standards or harm to a patient. The first step is to report internally. - **D. Health and safety**: This is not directly relevant to the situation unless the procedure poses an immediate health and safety risk. By filing an incident report, you ensure that the situation is addressed appropriately and that patient safety and professional standards are upheld.

Answer 114

The most appropriate course of action for this patient is: **Arrange extracorporeal shock wave lithotripsy (ESWL)**. ### Explanation: - The patient is a 25-year-old man with a **9mm left-sided proximal ureteric calculus**, normal renal function, and no signs of infection or obstruction. For a stone of this size in the proximal ureter, **ESWL** is often the first-line treatment. ESWL is a non-invasive procedure that uses shock waves to break the stone into smaller fragments, which can then pass naturally through the urinary tract. ### Why not the other options? 1. **Percutaneous nephrolithotomy (PCNL)**: This is typically reserved for larger stones (>20mm) or complex cases, such as staghorn calculi. It is not necessary for a 9mm stone. 2. **Review in 4 weeks with KUB x-ray**: While conservative management with monitoring might be considered for smaller stones (<5mm), a 9mm stone is unlikely to pass spontaneously and requires active intervention. 3. **Ureteroscopy and stent insertion**: Ureteroscopy is an option, but it is more invasive than ESWL and is usually reserved for cases where ESWL has failed or is contraindicated. 4. **Open ureteric stone extraction**: This is rarely used nowadays due to the availability of less invasive techniques like ESWL and ureteroscopy. ### Summary: For a 9mm proximal ureteric stone in a patient with normal renal function, **ESWL** is the most appropriate and least invasive first-line treatment.

Answer 115

The most likely diagnosis for this patient is: **E. Primary biliary cholangitis (formerly known as primary biliary cirrhosis)**. ### Explanation: - The patient is a 25-year-old man with a **6-month history of mild jaundice, dark urine, and mild itching**. These symptoms are suggestive of **cholestatic liver disease**. - **Primary biliary cholangitis (PBC)** is an autoimmune condition that primarily affects the small bile ducts in the liver, leading to cholestasis (impaired bile flow). It is more common in middle-aged women but can occur in men and younger individuals. Key features include: - **Jaundice** - **Pruritus (itching)** - **Dark urine** (due to bilirubinuria) - Elevated alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) levels. ### Why not the other options? 1. **A. Carcinoma of the duodenum**: This is unlikely in a 25-year-old without other symptoms such as weight loss, abdominal pain, or vomiting. 2. **B. Choledocholithiasis**: This typically presents with acute symptoms such as biliary colic (severe right upper quadrant pain), fever, and jaundice. It is less likely to cause a 6-month history of mild jaundice and itching. 3. **C. Gilbert syndrome**: This is a benign condition characterized by intermittent mild jaundice due to unconjugated hyperbilirubinemia. It does not cause dark urine, itching, or cholestasis. 4. **D. Hepatitis C**: While hepatitis C can cause jaundice, it is usually associated with acute hepatitis (e.g., fatigue, nausea, elevated transaminases) or chronic liver disease. It does not typically present with isolated cholestatic features like itching and dark urine over 6 months. ### Summary: The patient's symptoms of **jaundice, dark urine, and itching** over 6 months are most consistent with **primary biliary cholangitis (PBC)**, a chronic cholestatic liver disease. Further investigations, such as liver function tests (elevated ALP and GGT), antimitochondrial antibodies (AMA), and imaging, would help confirm the diagnosis.

Answer 116

The most likely cause of **painless frank haematuria** in a 58-year-old man is: **Transitional cell carcinoma (TCC) of the bladder**. ### Explanation: - **Painless frank haematuria** is a classic presentation of **transitional cell carcinoma (TCC)** of the bladder, which is the most common type of bladder cancer. Risk factors include smoking, exposure to certain chemicals (e.g., aniline dyes), and older age. - Bladder cancer typically presents with **intermittent, painless haematuria**, and the patient may also have irritative voiding symptoms (e.g., urgency, frequency) if the tumor is located near the bladder neck. ### Why not the other options? 1. **Renal adenocarcinoma (renal cell carcinoma)**: While renal cell carcinoma can cause haematuria, it is often associated with flank pain, a palpable abdominal mass, or systemic symptoms (e.g., weight loss, fever). Painless haematuria is more characteristic of bladder cancer. 2. **Neuroblastoma**: This is a tumor of the sympathetic nervous system that primarily occurs in children. It is extremely rare in adults and would not present with isolated haematuria. 3. **Squamous cell carcinoma of the bladder**: This is a rare type of bladder cancer, usually associated with chronic irritation (e.g., long-term indwelling catheter or schistosomiasis infection). It is less common than TCC and would not be the first consideration in this case. 4. **Phaeochromocytoma**: This is a tumor of the adrenal medulla that secretes catecholamines, leading to episodic hypertension, palpitations, and headaches. It does not cause haematuria. ### Summary: In a 58-year-old man with **painless frank haematuria**, the most likely diagnosis is **transitional cell carcinoma (TCC) of the bladder**. Further investigations, such as **cystoscopy** and imaging (e.g., CT urogram), would be required to confirm the diagnosis.

Answer 117

Based on the clinical information provided, this 73-year-old man has several concerning findings: 1. History of prostatectomy for prostate cancer 2. Significantly elevated PSA (55) 3. Lower back pain 4. Osteosclerotic lesions in L3 and L4 vertebrae These findings are consistent with metastatic prostate cancer to the spine. The osteosclerotic (bone-forming) lesions are typical of prostate cancer metastasis, and the rising PSA after prostatectomy strongly suggests recurrent disease. The best treatment strategy for this patient would be: **Androgen suppression, bisphosphonates and radiotherapy** This multifaceted approach addresses several aspects of the disease: 1. **Androgen suppression therapy** (also called hormone therapy or ADT - androgen deprivation therapy) remains the backbone of treatment for metastatic prostate cancer, as most prostate cancers are hormone-sensitive. This can be achieved through medications like LHRH agonists/antagonists (e.g., leuprolide, goserelin) and/or anti-androgens. 2. **Bisphosphonates** (such as zoledronic acid) help manage bone metastases by: - Reducing skeletal-related events - Decreasing bone pain - Potentially slowing progression of bone metastases - Reducing risk of pathological fractures 3. **Radiotherapy** to the affected vertebrae can: - Provide pain relief - Control local disease - Prevent pathological fractures - Reduce risk of spinal cord compression The other options are less appropriate: - Posterior spinal fusion or vertebral body reconstruction would be overly invasive as first-line treatment and don't address the systemic nature of the disease - Bisphosphonates and radiotherapy alone, without addressing the hormonal driver of the disease, would be insufficient - Radiotherapy alone wouldn't address the systemic nature of the disease or provide bone support This patient should also be evaluated for other systemic therapies depending on disease characteristics, including possibly chemotherapy, immunotherapy, or targeted therapies if appropriate.

Answer 118

Given the clinical scenario of a 39-year-old man with a left-sided varicocele and normal testis on palpation, the most appropriate next step would be: **Abdominal ultrasound** Here's why this is the correct approach: 1. While varicoceles are common and often benign, a new-onset varicocele in an adult male, particularly on the left side, raises concern for possible renal tumor with obstruction of the left renal vein. This is because: - The left testicular vein drains directly into the left renal vein - A renal tumor (especially renal cell carcinoma) can obstruct venous return, causing a varicocele - This is known as the "Varicocele Sign" 2. The abdominal ultrasound would allow visualization of the kidneys and retroperitoneum to rule out a renal mass or other abdominal pathology that could be causing venous obstruction. Other options are less appropriate because: - **Scrotal ultrasound**: While this would confirm the varicocele, it wouldn't identify the potentially more serious underlying cause. It could be a reasonable second step if the abdominal ultrasound is negative. - **Scrotal exploration and ligation**: This would be premature without first ruling out a more serious underlying cause. Surgical intervention for a varicocele is typically considered for pain, infertility, or testicular atrophy - none of which are mentioned in this case. - **Left orchidectomy**: This is far too aggressive without evidence of testicular pathology, especially since the testis is normal on palpation. - **Discharge**: This would miss a potentially serious underlying condition and is inappropriate without further investigation. After the abdominal ultrasound, if a renal or retroperitoneal mass is identified, appropriate referral to urology/oncology would be indicated. If the ultrasound is negative, then a scrotal ultrasound could be considered as a next step to further evaluate the varicocele and testis.

Answer 119

Based on the clinical description of a soft fluctuant scrotal swelling that cannot be separated from the testis and transilluminates with a pen torch, this is most consistent with a hydrocele. The best course of action would be: **Jaboulay procedure via scrotal approach** Here's why this is the most appropriate management: 1. The clinical findings (fluctuant, transilluminating, inseparable from testis) are classic for a simple hydrocele in an adult. 2. The Jaboulay procedure is a standard surgical treatment for hydrocele in adults that involves: - Scrotal approach to access the hydrocele - Evacuation of the hydrocele fluid - Excision of the redundant tunica vaginalis - Plication (folding and suturing) of the remaining tunica behind the testis - This prevents recurrence by eliminating the space where fluid can reaccumulate The other options are less appropriate because: - **Ligation of patent processus vaginalis (via either inguinal or scrotal approach)**: This would be appropriate for a communicating hydrocele or indirect inguinal hernia, typically seen in children. The description doesn't suggest communication with the peritoneal cavity, and the patient appears to be an adult. - **Lords procedure**: While this is another hydrocele repair technique, it's typically used for smaller hydroceles. The Lords procedure involves multiple small punctures in the hydrocele wall rather than excision and is generally less effective for larger hydroceles. - **Aspiration**: This is only a temporary measure for hydroceles and has a high recurrence rate. It might be considered for temporary relief in poor surgical candidates or for diagnostic purposes, but is not definitive treatment. Without knowing the patient's age or other clinical details, the Jaboulay procedure remains the most appropriate definitive treatment for what appears to be a simple hydrocele in an adult patient.

Answer 120

The most likely diagnosis for this 3-month-old boy with a **firm mass affecting the right spermatic cord distally**, where the **testis is felt separately**, is: **Rhabdomyosarcoma**. ### Explanation: - **Rhabdomyosarcoma** is a malignant tumor of mesenchymal origin and is the most common soft tissue sarcoma in children. It can occur in the genitourinary tract, including the spermatic cord, and often presents as a **firm, painless mass**. - In this case, the mass is distinct from the testis, which suggests it arises from the spermatic cord rather than the testis itself. This is a classic presentation for **paratesticular rhabdomyosarcoma**. ### Why not the other options? 1. **Inguino-scrotal hernia**: This typically presents as a soft, reducible swelling in the scrotum that may extend into the inguinal canal. It is not firm, and the testis is not felt separately. 2. **Leydig cell tumor**: This is a rare testicular tumor that arises from the testis itself, not the spermatic cord. The testis would not be felt separately from the mass. 3. **Torsion of testicular hydatid**: This typically presents with acute pain and a tender, small nodule at the upper pole of the testis. It does not cause a firm mass in the spermatic cord. 4. **Hydrocele**: This presents as a soft, fluid-filled swelling around the testis. It is not firm, and the testis is not felt separately. ### Summary: The **firm mass affecting the spermatic cord** with the **testis felt separately** is most consistent with **rhabdomyosarcoma**. Further investigations, such as **ultrasound** and **biopsy**, would be required to confirm the diagnosis. Early referral to a pediatric oncologist is essential for appropriate management.

Answer 121

The expected nerve lesion causing this deformity is: **D. Anterior interosseous nerve**. ### Explanation: - The **anterior interosseous nerve** is a branch of the **median nerve** that innervates the **flexor pollicis longus (FPL)**, **flexor digitorum profundus (FDP)** to the index and middle fingers, and the **pronator quadratus**. - Inability to lift the thumb from the table while the palm is facing upwards (loss of flexion at the interphalangeal joint of the thumb) suggests weakness or paralysis of the **flexor pollicis longus (FPL)**, which is supplied by the anterior interosseous nerve. This condition is known as **anterior interosseous nerve syndrome** or **Kiloh-Nevin syndrome**. ### Why not the other options? 1. **A. Radial nerve**: The radial nerve primarily innervates the extensor muscles of the wrist and fingers. A radial nerve lesion would cause wrist drop and inability to extend the fingers, not loss of thumb flexion. 2. **B. Posterior interosseous nerve**: This is a branch of the radial nerve that innervates the extensor muscles of the forearm. A lesion would result in weakness of finger and wrist extension, not thumb flexion. 3. **C. Median nerve**: A proximal median nerve lesion would cause weakness in thumb abduction and opposition (due to thenar muscle involvement) and sensory loss in the lateral palm and fingers. However, the specific inability to flex the thumb suggests an isolated anterior interosseous nerve lesion. 4. **E. Ulnar nerve**: The ulnar nerve innervates the intrinsic muscles of the hand (e.g., interossei, hypothenar muscles) and the flexor digitorum profundus to the ring and little fingers. A lesion would cause claw hand deformity and weakness in finger abduction/adduction, not isolated thumb flexion loss. ### Summary: The inability to lift the thumb from the table (loss of thumb flexion) is most consistent with a lesion of the **anterior interosseous nerve**, a branch of the median nerve. This condition is known as **anterior interosseous nerve syndrome**.

Answer 122

Based on the clinical information provided, this 56-year-old man has a 2cm nodule in the left lobe of the prostate that is suspected to be cancer, with no evidence of metastasis on comprehensive imaging. The most appropriate next step would be: **Prostatic biopsy** Here's why this is the correct approach: 1. **Diagnostic confirmation is essential**: Despite the suspicious nodule and imaging findings suggesting cancer, definitive tissue diagnosis is absolutely required before proceeding with any definitive treatment. Without a biopsy: - We don't have confirmation that the nodule is actually malignant - We don't know the Gleason score/Grade Group, which is crucial for treatment planning - We can't determine other histological features that might influence treatment decisions 2. **Treatment planning requires histopathology**: The choice between surgery, radiation, active surveillance, or other approaches depends heavily on: - Gleason score/Grade Group - Percentage of positive cores - Perineural invasion - Other histological features 3. **Patient counseling and informed consent**: To properly discuss treatment options with the patient, we need the pathology results to provide accurate information about prognosis and treatment success rates. The other options would be premature at this stage: - **Robotic prostatectomy or Open prostatectomy**: These are definitive surgical treatments that should only be performed after tissue diagnosis and proper risk stratification. - **Transvesical prostatectomy**: This approach is typically used for benign prostatic hyperplasia, not cancer, and would be inappropriate regardless. - **Radical pelvic radiotherapy**: Like surgery, this definitive treatment should only be offered after tissue diagnosis and proper discussion of all treatment options. After the biopsy results are available, then the patient can be appropriately counseled on treatment options, which might include radical prostatectomy (robotic or open), radiation therapy, or in some cases, active surveillance, depending on the risk classification of his cancer.

Answer 123

The most likely diagnosis for this 30-year-old male with **gynaecomastia** and a **testicular nodule** is: **Leydig cell tumour**. ### Explanation: - **Leydig cell tumours** are rare testicular tumours that arise from the Leydig cells in the testis. They are often hormonally active and can secrete **oestrogens**, leading to **gynaecomastia** (breast enlargement in males) due to an imbalance in the oestrogen-to-testosterone ratio. - These tumours typically present as a **painless testicular mass** and may be associated with hormonal symptoms such as gynaecomastia, decreased libido, or infertility. ### Why not the other options? 1. **Oestrogen abuse**: While exogenous oestrogen use can cause gynaecomastia, it would not explain the presence of a testicular nodule. 2. **Seminoma with syncytiotrophoblast giant cells**: Seminomas are germ cell tumours that typically do not secrete hormones. Although syncytiotrophoblast giant cells can produce beta-hCG (human chorionic gonadotropin), this is less commonly associated with gynaecomastia compared to Leydig cell tumours. 3. **Teratoma**: Teratomas are germ cell tumours that are usually hormonally inactive and do not cause gynaecomastia. 4. **Sarcoma**: Testicular sarcomas are rare and are not typically associated with hormonal symptoms like gynaecomastia. ### Summary: The combination of **gynaecomastia** and a **testicular nodule** in a young male is most suggestive of a **Leydig cell tumour**. Further evaluation with **testicular ultrasound** and **hormonal assays** (e.g., testosterone, oestradiol, LH, FSH) is necessary to confirm the diagnosis. Surgical excision (radical orchiectomy) is the definitive treatment.

Answer 124

Here's the breakdown of why the best answer is B and why the others are not: A. Ward transfer should be arranged until temperature is 36°C or above: Transferring the patient without actively addressing the hypothermia is not appropriate. Hypothermia can lead to serious complications, and the patient needs immediate intervention. B. IV warm saline: This is a good initial step. Warming the patient from the inside out is a basic hypothermia management strategy. Warmed IV fluids help increase the core body temperature. C. Make ambient temperature 19°C: This would actually worsen the hypothermia. A cold room will further draw heat away from the patient. D. Warm by Bair Hugger and do the operation under general anesthesia: The patient has already had the operation. While a Bair Hugger (forced-air warming device) is an excellent method for warming, it's being suggested in the context of re-doing the surgery, which is unnecessary. E. Do the operation under local anesthesia: The patient has already had the operation. Changing the anesthesia type is not relevant to the current situation. Therefore, the most appropriate initial intervention is B. IV warm saline. Additional steps to consider (beyond the options given): Assess the patient: Check vital signs (heart rate, blood pressure, respiratory rate, oxygen saturation), level of consciousness, and look for any other signs of complications. Oxygen: Administer supplemental oxygen to help with oxygen delivery to tissues. Warm blankets: Apply warm blankets to the patient's skin. Monitor core temperature: Continuously monitor the patient's temperature to assess the effectiveness of warming interventions. Investigate the cause: Try to determine why the patient became hypothermic in the first place (e.g., prolonged anesthesia, cold operating room, inadequate warming measures during surgery). Consider other warming methods: If IV fluids and blankets are not sufficient, consider other active warming methods like a Bair Hugger, radiant warmers, or warm water immersion.

Answer 125

The most likely cause of severe abdominal pain, vomiting, and swelling at the stoma site three months after colostomy reversal is **C. Incarcerated incisional hernia**. ### Explanation: - **Incarcerated incisional hernia**: After colostomy reversal, the site where the stoma was created is a potential weak point in the abdominal wall. An incisional hernia can develop at this site, and if the hernia becomes incarcerated (trapped), it can lead to bowel obstruction, severe pain, and swelling. This is a surgical emergency. - **Wound dehiscence (A)**: This typically occurs early in the postoperative period, not three months later. - **Intestinal obstruction (B)**: While possible, it would not specifically explain the swelling at the stoma site unless it is related to a hernia. - **Wound infection (D)**: This would present with redness, warmth, and discharge, but not typically with severe pain and vomiting unless it has progressed to an abscess or systemic infection. - **None of the above (E)**: This is less likely given the clinical presentation. ### Conclusion: The symptoms strongly suggest an **incarcerated incisional hernia**, which requires urgent surgical evaluation and management.

Answer 126

The correct answer is: B. Ankle plantar flexion Explanation: Anterior compartment syndrome occurs when increased pressure within the anterior compartment of the leg compromises circulation and function of the enclosed tissues. The anterior compartment contains the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertius muscles, all of which are primarily responsible for dorsiflexion of the ankle and extension of the toes. One of the key clinical signs of anterior compartment syndrome is severe pain on passive stretching of the affected muscles. Since the anterior compartment muscles are dorsiflexors, passive plantar flexion of the ankle (opposite movement) stretches these muscles, exacerbating the pain oai_citation:0‡Emergency-Pastest.pdf. Key points: • Early sign: Severe pain, particularly on passive muscle stretch. • Late signs: Paraesthesia (deep peroneal nerve involvement), muscle weakness, and potential ischemic damage. • Diagnosis: Primarily clinical, supported by compartment pressure measurements (>30-35 mmHg or a delta pressure <30 mmHg). • Management: Urgent fasciotomy if compartment syndrome is suspected. Delayed treatment can lead to irreversible muscle and nerve damage.

Answer 127

The answer is B) Wormian bones. Here's why: * Type 1 collagen is a crucial component of bone, skin, tendons, and other connective tissues. A defect in Type 1 collagen leads to Osteogenesis Imperfecta (OI), a group of genetic disorders characterized by brittle bones. * Wormian bones are extra, small bones that can appear within the sutures of the skull. They are often seen in OI and are a characteristic radiographic finding. Let's look at why the other options are less likely: * A) Irregular patches of ossification: While OI can affect bone formation, "irregular patches" isn't the most specific or characteristic finding. This description is too general and could apply to various conditions. * C) Multiple fractures: While multiple fractures are a consequence of OI due to bone fragility, they aren't the most characteristic radiographic finding. Fractures are a symptom, not the underlying skeletal abnormality visualized on x-ray. * D) Dense metaphyseal bands: These are more commonly associated with other conditions, such as lead poisoning or rickets. * E) Bone within bone appearance: This is a classic radiographic finding of osteopetrosis, a different condition involving abnormally dense bones, not brittle bones like in OI.

Answer 128

The most likely diagnosis for this 12-year-old boy with poor muscular development, hyper-mobile fingers, multiple fractures, and irregular ossification is Osteogenesis Imperfecta. Explanation: • Osteogenesis Imperfecta (OI) is a genetic disorder characterized by brittle bones that fracture easily due to defective collagen formation. • Clinical features include: • Frequent fractures with minimal trauma • Blue sclerae (though not always present) • Hypermobile joints • Poor muscle development • Irregular ossification on X-rays • X-ray Findings: • Multiple fractures of long bones • Wormian bones (small irregular bones in the skull) • Thin cortices of bones with variable density Other options: • Osteoporosis: More common in the elderly; unlikely in a child without underlying causes. • Scurvy (Vitamin C deficiency): Causes bone pain, gingival bleeding, and perifollicular hemorrhages, but not hypermobility. • Osteopetrosis: Characterized by overly dense bones due to defective osteoclast function, leading to fractures, anemia, and cranial nerve compression oai_citation:0‡(A & L LANGE SERIES) Kim E. Barrett, Susan M. Barman, Heddwen L. Brooks, Jason Yuan, Scott Boitano - Ganong’s Review of Medical Physiology-McGraw-Hill Medical _ Education (2019).pdf. • Osteomalacia: Affects adults with vitamin D deficiency and is more associated with bone softening rather than frequent fractures in childhood oai_citation:1‡LibraryFile_151638_59.pdf. Thus, Osteogenesis Imperfecta is the most appropriate diagnosis based on the clinical and radiological findings.

Answer 129

The correct answer is: **B. Common peroneal nerve** ### Explanation: A **supracondylar femur fracture** can potentially injure the **common peroneal nerve**, which is a branch of the sciatic nerve. The common peroneal nerve wraps around the neck of the fibula and is relatively superficial, making it vulnerable to injury during trauma or fractures in the distal femur or proximal tibia/fibula region. Injury to this nerve can result in **foot drop** (inability to dorsiflex the foot) and sensory deficits on the lateral leg and dorsum of the foot. The other nerves listed are less likely to be directly affected by a supracondylar femur fracture: - **A. Sciatic nerve**: While the sciatic nerve is in the vicinity, it is less commonly injured in this type of fracture. - **C. Tibial nerve**: This nerve is deeper and less likely to be injured in this fracture. - **D. Sural nerve**: A sensory nerve that is not typically affected by this fracture. - **E. Saphenous nerve**: A branch of the femoral nerve, which is not typically injured in this fracture.

Answer 130

The most likely cause of this patient’s “trash foot” is: A. Thrombosed EVAR graft Explanation: • “Trash foot” (also known as embolic or microembolization syndrome) occurs due to cholesterol embolization or thromboembolic debris showering into the distal arterial circulation. • The patient has a history of EVAR, making thrombosis or embolization from the graft the most probable etiology. • Palpable pulses in the affected limb suggest that the major arteries are still patent, making a proximal large vessel occlusion (like popliteal aneurysm thrombosis or atrial fibrillation embolism) less likely. • Cholesterol embolization from the aortic graft can lead to digital ischemia, cyanosis, and pain, characteristic of “blue toe syndrome” or “trash foot”. Why not the other options? • B. Popliteal aneurysm: This can cause acute limb ischemia but usually presents with absent pulses distal to the occlusion, which is not seen in this patient. • C. Atrial fibrillation: AF can cause large embolic events leading to sudden arterial occlusion, but it typically results in a non-palpable pulse distal to the occlusion, unlike the scenario given. • D. Ruptured AAA: A ruptured AAA leads to hemodynamic instability, severe abdominal/back pain, and shock, which this patient does not have.

Answer 131

1) The endometrium is part of the uterus, and its lymphatic drainage follows specific patterns that are important for cancer spread. 2) The lymphatic drainage of the uterus primarily occurs in three directions: - Laterally along the broad ligament - Along the round ligament - Along the uterosacral ligaments 3) The primary lymphatic drainage of endometrial cancer follows this pattern: - First to the pelvic lymph nodes (external and internal iliac nodes) - Then to the para-aortic nodes - The superficial and deep inguinal nodes are not in the primary drainage pathway 4) Between the external and internal iliac nodes, the primary drainage is to the: EXTERNAL ILIAC LYMPH NODES 5) The para-aortic nodes are typically involved as secondary drainage, after the pelvic nodes. Therefore, the answer is A. External iliac lymph nodes. This represents the primary and most common lymphatic drainage pathway for endometrial cancer. While other nodes can become involved (particularly para-aortic nodes) as the disease progresses, the external iliac nodes are the primary drainage site.

Answer 132

The correct answer is: **B. Fundus of stomach** ### Explanation: The scenario describes a **splenic artery aneurysm**, which is the most common aneurysm of the visceral arteries. The splenic artery runs along the upper border of the pancreas and is often tortuous. Ligation of the splenic artery can lead to ischemia of the **spleen** and potentially other structures supplied by its branches. The **fundus of the stomach** is at risk because it receives blood supply from the **short gastric arteries**, which are branches of the splenic artery. Ligation of the splenic artery can compromise blood flow to these vessels, affecting the fundus of the stomach. ### Incorrect Options: - **A. Head of pancreas**: The head of the pancreas is primarily supplied by the **superior pancreaticoduodenal artery** (from the gastroduodenal artery) and the **inferior pancreaticoduodenal artery** (from the superior mesenteric artery), not the splenic artery. - **C. Colon**: The colon is supplied by the **superior mesenteric artery** (right and middle colic arteries) and the **inferior mesenteric artery** (left colic artery), not the splenic artery. - **D. Duodenum**: The duodenum is supplied by the **pancreaticoduodenal arteries**, not the splenic artery. - **E. Small bowel**: The small bowel is supplied by the **superior mesenteric artery**, not the splenic artery. Thus, the **fundus of the stomach (B)** is the most likely structure to be affected after ligation of the splenic artery, other than the spleen.

Answer 133

The correct answer is: A. Facial nerve Explanation: • Hyperacusis (increased sensitivity to sound) occurs due to paralysis of the stapedius muscle, which is normally responsible for dampening loud sounds. • The stapedius muscle is innervated by the facial nerve (CN VII). • If the facial nerve is injured, stapedius muscle paralysis results in an inability to modulate sound, leading to hyperacusis. Why not the other options? • B. Mandibular branch of the trigeminal nerve (V3) → Innervates the tensor tympani muscle, which also plays a role in sound modulation, but damage does not usually cause hyperacusis. • C. Maxillary branch of the trigeminal nerve (V2) → Provides sensory innervation to the midface and maxillary sinus, not related to sound modulation. • D. Ophthalmic branch of the trigeminal nerve (V1) → Provides sensory innervation to the forehead, cornea, and upper eyelid, unrelated to hearing. • E. Vestibulocochlear nerve (CN VIII) → Responsible for hearing and balance, but its injury causes sensorineural hearing loss, vertigo, or tinnitus, not hyperacusis. Key Learning Point: • Hyperacusis → Think facial nerve (CN VII) injury affecting the stapedius muscle.

Answer 134

Let me solve this step by step: 1) First, let's identify the anatomical landmarks: - Linea semilunaris is the lateral border of rectus abdominis muscle - Costal margin is the lower border of the ribcage - Their junction is in the right upper quadrant of the abdomen 2) At this specific junction point: - It's high in the abdomen (subcostal) - It's lateral (at the linea semilunaris) - This puts us in the right hypochondriac region 3) Let's consider which organs are in this region: - Liver - Gallbladder - Part of right kidney (but more posterior) - Cecum and appendix are much lower in the right iliac fossa 4) At this specific point: - The gallbladder fundus is typically found at the intersection of the linea semilunaris and costal margin - This is where the gallbladder projects beyond the liver's edge - This point is often used clinically as Murphy's point Therefore, the answer is A. Gall bladder fundus. Rationale: - The gallbladder fundus is specifically located at this anatomical landmark - The liver, while nearby, is more superior and medial - The kidney is more posterior - The cecum and appendix are far too inferior to be involved

Answer 135

The correct answer is: D. Diagnostic Laparoscopy Explanation: • This 19-year-old woman presents with acute right iliac fossa (RIF) pain, nausea, vomiting, localized guarding, and elevated inflammatory markers (WCC 13.5, CRP 70). • The most likely diagnosis is acute appendicitis, but in a young female, gynecological causes (e.g., ovarian cyst rupture, ectopic pregnancy, or pelvic inflammatory disease) must be ruled out. • Beta-hCG is negative, excluding an ectopic pregnancy. • Given the diagnostic uncertainty and the potential for gynecological pathology, diagnostic laparoscopy is the preferred approach. Why not the other options? • A. Open appendicectomy → Not the first-line approach if the diagnosis is uncertain. Minimally invasive techniques (laparoscopy) are preferred for both diagnosis and treatment. • B. Laparotomy → Too invasive for an undifferentiated RIF pain case. It is typically reserved for complications like perforation or generalized peritonitis. • C. Abdominal ultrasound → Less sensitive for appendicitis in adults, especially if bowel gas obscures the appendix. More useful in pediatric patients. • E. Abdominal CT scan → While highly sensitive for appendicitis, CT is avoided in young women due to radiation exposure unless absolutely necessary. Key Learning Point: • Young female with RIF pain? Think gynecological causes! • Diagnostic laparoscopy is the best diagnostic and therapeutic approach when appendicitis is suspected but uncertainty remains.

Answer 136

The correct answer is Papillary thyroid carcinoma (PTC). Explanation: • Papillary thyroid carcinoma (PTC) is the most common thyroid cancer in children, including a 3-year-old boy. • It accounts for >90% of pediatric thyroid cancers and has a good prognosis, even with lymph node involvement. • Medullary thyroid carcinoma (MTC) is seen in children, but it is much rarer and usually associated with MEN2A or MEN2B syndromes. • Follicular carcinoma is more common in older children and adults. • Hurthle cell carcinoma is a rare variant of follicular carcinoma, very uncommon in young children. • Anaplastic carcinoma is almost never seen in children; it is an aggressive cancer affecting older adults. Correct answer: Papillary thyroid carcinoma (PTC)

Answer 137

The correct answer is: B. Anterior talofibular ligament (ATFL) Explanation: • The anterior talofibular ligament (ATFL) is the most commonly injured ligament in ankle sprains, especially in inversion injuries. • It is part of the lateral ligament complex of the ankle and is the weakest of the three lateral ligaments. • It is often injured when the foot is plantarflexed and inverted, which is a common mechanism in sports injuries. Why not the other options? • A. Posterior talofibular ligament: Less commonly injured, usually affected in severe ankle sprains or dislocations. • C. Deltoid ligament: A strong medial ligament, more resistant to injury; sprains here occur with eversion injuries. • D. Calcaneotalar ligament: Not commonly injured in typical ankle sprains. • E. None of the above: Incorrect, as ATFL is the most frequently injured ligament. This question has been seen in MRCS recall exams oai_citation:0‡MRCS RECALL ALL JAN EXAMS 2016 - 2021.pdf.

Answer 138

This is a medical question about anatomy and surgical procedures. Here's the breakdown of the answer: Understanding the Posterior Approach to the Knee A posterior approach to the knee means the surgeon is working from behind the knee. The popliteal fossa is the diamond-shaped area behind the knee, and it contains vital structures. Layers of the Popliteal Fossa When dissecting from the skin in the popliteal fossa, you encounter structures in layers. Here's the general order from superficial to deep: * Skin and superficial fascia: This is the outermost layer. * Deep fascia: A tough layer of connective tissue. * Nerve: The tibial nerve is typically the most superficial of the major structures within the popliteal fossa itself. * Vein: The popliteal vein usually lies somewhat deeper than the nerve. * Artery: The popliteal artery is the deepest of the major vessels in the popliteal fossa. * Muscles: The popliteus muscle is encountered even deeper, as it forms part of the floor of the popliteal fossa. The Answer Given the layers, the tibial nerve (D) would be the first major structure encountered when dissecting deep from the skin incision in a posterior approach to the knee. Important Note: This is a simplified explanation. Actual anatomy can vary, and surgeons must have a thorough understanding of the region's anatomy to avoid complications.

Answer 139

The presence of multiple dark irregular small stones after a cholecystectomy suggests the possibility of pigment stones, particularly if they are dark in color. These stones are primarily composed of bilirubin. In this case, the elevation of conjugated bilirubin (Option C) is the most likely cause of the formation of these dark stones, as conjugated bilirubin is associated with the formation of pigment stones. Unconjugated bilirubin, while it does play a role in the formation of stones, typically does not lead to the formation of dark stones in the gallbladder. Therefore, the correct answer is: C. Conjugated bilirubin

Answer 140

The most likely artery to be affected in the case of a massive bleeding gastric ulcer located between the antrum and the body of the stomach is: **D. Left gastric artery** ### Explanation: - The **left gastric artery** is a major branch of the celiac trunk and supplies blood to the lesser curvature of the stomach, including the region between the antrum and the body of the stomach. This area is a common site for gastric ulcers, and bleeding from this region is often due to erosion of the left gastric artery or its branches. - The other arteries listed (short gastric, left gastroepiploic, and right gastroepiploic) supply different regions of the stomach and are less likely to be involved in bleeding from an ulcer in this specific location. Thus, the correct answer is **D. Left gastric a**.

Answer 141

The best postoperative anticoagulation option for a patient with congenital antithrombin III (ATIII) deficiency undergoing sigmoid colectomy is lifelong heparin therapy (Option E). Explanation: • Congenital ATIII deficiency is a thrombophilic disorder that leads to an increased risk of venous thromboembolism (VTE), especially in surgical settings. • Heparin works by enhancing the activity of antithrombin III, making it the most effective anticoagulant in this scenario. • Warfarin alone is not sufficient as it inhibits vitamin K-dependent clotting factors but does not directly address the deficiency of ATIII. • Duration: Lifelong anticoagulation is recommended for patients with severe congenital ATIII deficiency, as they are at high risk of recurrent thrombosis. Thus, Option E (Heparin for life) is the correct answer.

Answer 142

The pathological finding in pulmonary embolism is increased ventilation-perfusion (V/Q) ratio, making Option D the correct answer. Explanation: Pulmonary embolism (PE) occurs when a thrombus, typically from a deep vein thrombosis (DVT), lodges in the pulmonary vasculature, causing obstruction to blood flow. This results in the following pathophysiological changes: 1. Increased Ventilation-Perfusion (V/Q) Ratio: • The embolism blocks blood flow to parts of the lung, causing areas where ventilation is maintained but perfusion is reduced, leading to an increased V/Q ratio. • This results in inefficient gas exchange and hypoxemia. 2. Decreased Arterial PO₂ (Not Increased PO₂): • Since perfusion is blocked, oxygen cannot effectively reach the bloodstream from the affected lung regions, leading to decreased arterial oxygen levels. 3. Decreased or Normal PCO₂ (Not Increased PCO₂): • The hypoxemia from the embolism triggers hyperventilation, which leads to increased CO₂ elimination and decreased arterial PCO₂. 4. No Significant Increase in Diffusion: • Pulmonary embolism primarily affects perfusion rather than the diffusion capacity of the alveolar membrane.

Answer 143

The most likely diagnosis in this 4-month-old child with failure to thrive, recurrent chest infections, and dyspnea that worsens when lying flat at night is gastroesophageal reflux disease (GERD), making Option D the correct answer. Explanation: 1. Failure to Thrive (FTT): • GERD can cause poor weight gain due to frequent vomiting and reduced oral intake. 2. Recurrent Chest Infections: • GERD can lead to aspiration of gastric contents, causing recurrent respiratory infections and wheezing. 3. Dyspnea Worsening When Lying Flat (Orthopnea-like Symptoms in an Infant): • When lying down, reflux is more likely to occur, leading to choking, coughing, and awakening from sleep. Why Not the Other Options? • Tetralogy of Fallot (TOF) (A): • TOF presents with cyanotic episodes (Tet spells), usually triggered by crying or feeding. Murmur and echocardiography findings would confirm the diagnosis. • Congenital Diaphragmatic Hernia (CDH) (B): • CDH is usually diagnosed at birth due to severe respiratory distress. It would cause significant lung hypoplasia and be evident on imaging. • Asthma (C): • Rare in infants this young. Wheezing due to asthma would typically respond to bronchodilators and have an atopic history. • None of the Above (E): • GERD fits well with the described symptoms, making this choice unnecessary. Next Steps: • Diagnosis: Clinical history, pH monitoring, barium swallow study, or endoscopy if severe. • Management: • Conservative: Positioning therapy (keeping the infant upright after feeds), thickened feeds. • Medical: Proton pump inhibitors (PPIs) or H2 blockers for severe cases. • Severe cases may need fundoplication surgery. Thus, GERD (D) is the best answer.

Answer 144

The portion of blood present in the pulmonary circulation is approximately 18% of the total blood volume oai_citation:0‡(A & L LANGE SERIES) Kim E. Barrett, Susan M. Barman, Heddwen L. Brooks, Jason Yuan, Scott Boitano - Ganong’s Review of Medical Physiology-McGraw-Hill Medical _ Education (2019).pdf. Thus, the correct answer is B. 20 to 25%, as this is the closest range to the actual value.

Answer 145

The holosystolic murmur radiating to the axilla strongly suggests mitral regurgitation (MR). The expected chamber enlargement on transesophageal echocardiography would be the left atrium, making Option A (Left atrium) the correct answer. Explanation: 1. Mitral regurgitation (MR) occurs due to incompetent closure of the mitral valve, leading to backflow of blood into the left atrium during systole. 2. Hallmark Murmur: • Holosystolic murmur best heard at the apex and radiating to the axilla. 3. Effects on Cardiac Chambers: • Left atrium enlarges due to chronic volume overload. • Left ventricle may also dilate over time due to increased preload, but the left atrium is the first and most significantly affected chamber. 4. Confirmatory Test: • Transesophageal echocardiography (TEE) would show left atrial dilation and possible mitral valve pathology. Why Not the Other Options? • Left ventricle (B): Enlarges later in chronic MR but is not the primary chamber affected first. • Right ventricle (C) & Right atrium (D): These are more involved in tricuspid regurgitation or pulmonary hypertension, not MR. • Ventricular apex (E): Not an anatomical term for chamber enlargement. Thus, the correct answer is A. Left atrium.

Answer 146

The correct answer is C. Buccinator. Explanation: The foramen ovale transmits the mandibular nerve (V3), a branch of the trigeminal nerve (cranial nerve V). The muscles responsible for closing the mouth (elevation of the mandible) that are innervated by V3 include: 1. Temporalis (elevates and retracts the mandible) 2. Masseter (elevates the mandible) 3. Medial pterygoid (elevates the mandible) The lateral pterygoid is responsible for jaw opening (depression of the mandible) and side-to-side movements, so it is not involved in closing the mouth. Why is Buccinator (C) the correct answer? • Buccinator is NOT involved in jaw closure; it functions in chewing by keeping food between the teeth but does not move the mandible. • It is innervated by the facial nerve (CN VII), not the mandibular nerve (V3). Thus, if the mandibular nerve (V3) is injured at the foramen ovale, all muscles of mastication will be affected except Buccinator, making C. Buccinator the correct choice.

Answer 147

The correct answer is B. Lumbar splanchnic nerve. Explanation: Ejaculation involves two main phases: 1. Emission (Sympathetic Control - Hypogastric Nerve, L1-L2) • Involves contraction of the vas deferens, seminal vesicles, and prostate to propel semen into the urethra. • Controlled by the lumbar splanchnic nerves (L1-L2), which contribute to the inferior hypogastric plexus. 2. Ejaculation (Somatic and Parasympathetic Control - Pudendal Nerve, S2-S4) • Rhythmic contraction of the bulbospongiosus muscle via the pudendal nerve (S2-S4). How Does Surgery Affect This? • Retroperitoneal lymph node dissection (RPLND) or abdominoperineal surgery can injure the lumbar splanchnic nerves (L1-L2), leading to loss of emission (failure to transport sperm into the urethra), resulting in retrograde ejaculation or anejaculation. Why Not the Other Options? • Pelvic splanchnic nerve (A) (S2-S4): Controls parasympathetic erection, not ejaculation. • Thoracic splanchnic nerve (C) (T5-T12): Primarily involved in abdominal visceral function, not ejaculation. • Pudendal nerve (D) (S2-S4): Controls somatic ejaculation (muscle contraction) but does not control emission. • Iliolumbar nerve (E): Primarily involved in sensory and muscular function in the lower back, unrelated to ejaculation. Final Answer: B. Lumbar splanchnic nerve (L1-L2) is responsible for emission, and its injury leads to ejaculation failure.

Answer 148

The best nutritional option for a young man with midgut volvulus and 250 cm of small bowel left after massive resection depends on several factors, including the functionality of the remaining bowel, the patient's ability to tolerate oral intake, and the presence of any complications such as short bowel syndrome. Here’s a breakdown of the options: **A. Total parenteral nutrition (TPN):** - TPN is used when the patient cannot absorb sufficient nutrients through the gastrointestinal tract. While it may be necessary initially after massive resection, it is not the best long-term option due to risks like infections, liver dysfunction, and metabolic complications. **B. Can be fed orally:** - If the remaining 250 cm of small bowel is functional and the patient can tolerate oral intake, this is the best option. The small intestine can adapt over time, and oral feeding is the most natural and least invasive method. However, the patient may need supplemental vitamins, minerals, and possibly specialized oral formulas to meet nutritional needs. **C. Feeding jejunostomy:** - A feeding jejunostomy is an option if oral intake is insufficient or not tolerated. It allows direct feeding into the jejunum, bypassing the stomach. This may be useful in the short term but is not ideal for long-term management if oral feeding is possible. **D. Percutaneous endoscopic gastrostomy (PEG):** - PEG is typically used for long-term enteral feeding when oral intake is not possible. However, it is less suitable for patients with short bowel syndrome, as the stomach and duodenum may not be the primary sites of nutrient absorption. **E. Nasogastric tube:** - A nasogastric tube is a short-term solution for feeding or decompression. It is not suitable for long-term nutritional support due to discomfort and risks like aspiration or tube displacement. **Best Answer:** **B. Can be fed orally** - If the patient can tolerate oral intake and the remaining small bowel is functional, oral feeding is the best option. The patient may require dietary modifications, supplements, and close monitoring to ensure adequate nutrition. If oral intake is insufficient, a combination of oral feeding and supplemental enteral nutrition (e.g., via a feeding jejunostomy) may be considered. TPN should only be used if enteral feeding is not feasible.

Answer 149

The best answer here is C. Nasogastric tube. Here's the reasoning: * Post-operative nutrition after bowel surgery in a patient with Crohn's disease requires careful consideration. The bowel needs time to heal, and oral intake may not be immediately tolerated. * A. Start oral: This is unlikely to be appropriate immediately after bowel surgery, especially with Crohn's disease, as it could irritate the healing bowel. * B. Start oral with special formula: While a special formula might be used later, it's not the first-line choice immediately post-op. The gut needs a rest. * C. Nasogastric tube: This allows for enteral feeding (feeding directly into the gut) which is preferred over parenteral nutrition (TPN) whenever possible. It provides nutrition while bypassing the surgical site and allowing the bowel to rest and heal. It's a less invasive option than TPN. * D. TPN with a peripheral line: TPN (Total Parenteral Nutrition) is a method of providing nutrition intravenously, bypassing the gut entirely. While TPN is sometimes necessary, it carries more risks (infection, blood clots) than enteral feeding and is generally reserved for situations where the gut cannot be used. A peripheral line isn't ideal for long-term TPN and is more suitable for short-term nutritional support. * E. TPN at home: TPN at home is a long-term solution. It's not the immediate course of action post-operatively. Therefore, a nasogastric tube for enteral feeding is the most appropriate initial approach for post-operative nutrition in this patient. TPN would be considered if enteral feeding is not tolerated or feasible.

Answer 150

The correct answer is: C. 10 cm above the radio-capitellar (radio-capitular) joint Explanation: • The radial nerve originates from the posterior cord of the brachial plexus and primarily courses posteriorly through the arm. • It travels through the spiral groove of the humerus but remains in the posterior compartment. • Around 10 cm above the radio-capitellar joint, the radial nerve pierces the lateral intermuscular septum and moves from the posterior to the anterior compartment. • It then continues anteriorly in the forearm, where it divides into the superficial (sensory) and deep (motor) branches at the level of the elbow. Why not the other options? • A. Spiral groove – The radial nerve is still in the posterior compartment at this point. • B. Cubital tunnel – This is related to the ulnar nerve, not the radial nerve. • D. 1 cm above the insertion of biceps – This is too distal; by this point, the radial nerve has already moved anteriorly. • E. None of the above – Incorrect, as option C is correct. Thus, the correct answer is C. 10 cm above the radio-capitellar joint.

Answer 151

The correct answer is: E. Tibialis posterior muscle Explanation: In the posterior compartment of the leg, structures are arranged from superficial to deep as follows: 1. Superficial layer – Gastrocnemius, soleus, plantaris 2. Deep layer – Popliteus, tibialis posterior (deepest), flexor digitorum longus, flexor hallucis longus 3. Neurovascular structures – The tibial nerve and posterior tibial artery run superficial to tibialis posterior. Why not the other options? • A. Tibial artery – Lies superficial to tibialis posterior. • B. Fibular artery – A branch of the posterior tibial artery, but still not as deep as tibialis posterior. • C. Tibial nerve – Runs with the posterior tibial artery, also superficial to tibialis posterior. • D. Saphenous nerve – This is a superficial cutaneous nerve in the leg, not in the deep posterior compartment. Thus, the deepest structure in the posterior compartment of the leg is the tibialis posterior muscle (E).

Answer 152

The inability to hold a paper between the thumb and index finger without the thumb flexing indicates that the patient is compensating for weakness of the adductor pollicis muscle. Normally, the adductor pollicis—innervated by the deep branch of the ulnar nerve—helps to hold the thumb in the proper position during pinch grip. When this muscle is weakened due to an injury to the deep branch of the ulnar nerve, the patient compensates by flexing the thumb using the flexor pollicis longus (innervated by the median nerve), which is seen as abnormal thumb flexion during the pinch. Thus, the described deformity is most consistent with an injury to the deep ulnar nerve. Answer: C. Deep ulnar nerve

Answer 153

The correct answer is: C. Flexor pollicis brevis Explanation: Carpal Tunnel Syndrome (CTS) is caused by compression of the median nerve as it passes through the carpal tunnel at the wrist. The median nerve innervates several muscles in the hand, primarily those in the thenar eminence and lumbricals to the lateral two fingers (index and middle fingers). Muscle Innervation and Function Flexor pollicis longus (Option A) – Median nerve (anterior interosseous branch, C8-T1) Involved in thumb flexion. This muscle remains functional in CTS because its nerve branch (anterior interosseous) arises before the carpal tunnel. Flexor digitorum profundus (Option B) – Dual innervation: median nerve (lateral part for index and middle fingers), ulnar nerve (medial part for ring and little fingers) This muscle flexes the DIP joints of fingers. Only the lateral half (index and middle fingers) is innervated by the median nerve, but it is not affected in CTS as it receives innervation proximal to the carpal tunnel. Flexor pollicis brevis (Option C) – Thenar muscle Superficial head: Innervated by the median nerve (via the recurrent branch), which gets compressed in CTS. Deep head: Innervated by the ulnar nerve. The superficial head is affected in CTS, leading to weak thumb flexion and opposition. 4th lumbrical (Option D) – Ulnar nerve (C8-T1) The lumbricals to the ring and little fingers are supplied by the ulnar nerve, which is not affected in CTS. Flexor carpi ulnaris (Option E) – Ulnar nerve The flexor carpi ulnaris is exclusively ulnar nerve innervated, so it is not involved in CTS. Why is Flexor Pollicis Brevis Most Likely to be Affected? The recurrent branch of the median nerve, which supplies the thenar muscles (including flexor pollicis brevis, abductor pollicis brevis, and opponens pollicis), arises after the carpal tunnel. Compression of the median nerve in CTS leads to thenar muscle weakness, causing difficulty in thumb opposition, flexion, and abduction. This results in thenar muscle atrophy, seen in chronic CTS cases. Key Clinical Features of Median Nerve Injury in CTS Pain and numbness in the lateral 3.5 fingers (thumb, index, middle, and half of the ring finger). Weakness of thumb opposition due to involvement of thenar muscles. Sparing of the flexor pollicis longus and flexor digitorum profundus (as their innervating branches arise proximal to the carpal tunnel). Wasting of the thenar eminence in chronic cases. Final Answer: C. Flexor pollicis brevis (superficial head) is most likely to be non-functional in carpal tunnel syndrome due to median nerve compression.

Answer 154

Here's how to break down the scenario to find the correct answer: * Right mastectomy: This surgery involves the breast and often the axillary lymph nodes, which are near the brachial plexus. * Weak right-hand grasp: This points to motor weakness in the hand. * Can write with thumb and index: This indicates that the median nerve function affecting the thenar muscles (used for fine motor skills like writing) is mostly intact. * Cannot lift suitcase: This suggests weakness in stronger grasping motions. Considering these points: * A. Posterior cord: The posterior cord gives rise to the axillary and radial nerves. Radial nerve damage would cause wrist drop and weakness in extension, which isn't the primary complaint here. * B. Anterior interosseous nerve: The anterior interosseous nerve (a branch of the median nerve) affects the flexor pollicis longus, flexor digitorum profundus (index and middle fingers), and pronator quadratus. Damage would disrupt the "OK" sign (pinching index finger and thumb), which is not described. * C. Medial brachial plexus: The medial brachial plexus gives rise to the medial cord, which gives rise to the medial pectoral, medial cutaneous nerve of the arm, medial cutaneous nerve of the forearm and the ulnar nerve. Damage to the medial brachial plexus would cause a wider range of symptoms than just a weak grip. * D. Recurrent median nerve: The recurrent branch of the median nerve innervates the thenar muscles. The patient can write, showing that this nerve is relatively intact. * E. Ulnar nerve: The ulnar nerve is responsible for the intrinsic muscles of the hand, which are crucial for grip strength. Damage to the ulnar nerve can cause weakness in grip and difficulty with fine motor movements. A weak grip, with the ability to write, is highly suggestive of ulnar nerve damage. Therefore, the most likely answer is E. Ulnar nerve.

Answer 155

The most likely type of bone lesion associated with prostatic bone metastases is: B. Reactive sclerosis Explanation: Prostate cancer commonly metastasizes to bones, particularly the axial skeleton (spine, pelvis, ribs). Unlike many other cancers that cause lytic (destructive) bone lesions, prostate cancer typically produces sclerotic (osteoblastic) lesions, leading to increased bone density on imaging studies such as X-rays and bone scans oai_citation:0‡Image-Pastest.pdf. These sclerotic lesions appear as areas of increased bone formation due to the osteoblastic activity stimulated by metastatic prostate cancer cells oai_citation:1‡EMRCS and pas test MCQs -1.pdf. Why not the other options? • Lytic lesions: More common in cancers like multiple myeloma, renal cell carcinoma, and lung cancer oai_citation:2‡EMRCS and pas test MCQs -1.pdf. • Mixed lytic and sclerotic lesions: Seen in some malignancies like breast cancer but are not the dominant pattern in prostate cancer. • Bone cysts: These are usually benign and not associated with prostate cancer metastases. • Osteopenia: Represents decreased bone density, whereas prostate cancer metastases result in increased bone density (sclerosis). Conclusion: Prostate cancer metastases are characteristically sclerotic, making reactive sclerosis the best answer.

Answer 156

The correct answer is: B. Perform a CT scan within 1 hour. Explanation: According to NICE guidelines, an urgent CT scan within 1 hour is indicated in patients with a depressed skull fracture, regardless of their GCS score, due to the increased risk of intracranial injury. Other indications for an immediate CT scan include: • GCS < 13 at any time • GCS < 15 two hours after the injury • Signs of basal skull fracture (e.g., Battle’s sign, haemotympanum) • Post-traumatic seizure • Focal neurological deficits • More than one episode of vomiting oai_citation:0‡Neurology-Pastest.pdf. Why not the other options? • A. Perform a CT scan in 8 hours – Delaying imaging in a patient with a depressed skull fracture is inappropriate as early detection of potential complications (e.g., intracranial bleeding) is crucial. • C. Monitor GCS and vital signs – While observation is important, imaging is necessary to rule out significant intracranial pathology. • D. Refer to a neurosurgeon – While neurosurgical involvement is needed if there is an underlying brain injury, the first step is to confirm the diagnosis with a CT scan. • E. Discharge with instructions for home observation – This is unsafe for a patient with a skull fracture, as they are at risk of delayed complications. Thus, an immediate CT scan within 1 hour is the next best step in management.

Answer 157

The correct answer is: D. Marginal mandibular branch Explanation: The marginal mandibular branch of the facial nerve supplies the depressor anguli oris, depressor labii inferioris, and mentalis muscles. Injury to this branch results in an asymmetrical smile because the patient cannot properly depress the corner of the mouth on the affected side oai_citation:0‡GET_THROUGH_MRCS_Anatomy.pdf. Why not the other options? • Temporal branch: Controls eyebrow movement and forehead muscles. • Zygomatic branch: Responsible for eye closure (orbicularis oculi). • Buccal branch: Involved in movements of the upper lip, such as blowing out cheeks. • Cervical branch: Controls the platysma, which affects neck movement rather than the smile. Since the marginal mandibular branch specifically affects lower lip movement and smiling, it is the best answer.

Answer 158

The correct answer is: A. Uncompensated respiratory acidosis Explanation: This patient has opioid overdose, which leads to respiratory depression and hypoventilation, causing CO₂ retention (hypercapnia). This results in a respiratory acidosis, as seen in the ABG findings: • pH: 7.28 (Low) → Indicates acidosis. • pCO₂: 60 mmHg (High) → Elevated CO₂ confirms respiratory cause. • HCO₃⁻: 24 mEq/L (Normal) → No metabolic compensation has occurred yet. Since the bicarbonate (HCO₃⁻) is still within the normal range, there is no renal compensation, meaning this is an acute (uncompensated) respiratory acidosis. Why not the other options? • B. Uncompensated metabolic acidosis → Would have low HCO₃⁻ and normal/low pCO₂, not high pCO₂. • C. Compensated respiratory acidosis → Compensation involves increased HCO₃⁻, which is not seen here. • D. Respiratory alkalosis → Would have high pH and low pCO₂, opposite to this case. • E. Compensated metabolic acidosis → Would have low HCO₃⁻ with low pCO₂ (respiratory compensation), which is not the case here. Conclusion: This is an acute opioid-induced respiratory acidosis due to hypoventilation. Naloxone should be administered to reverse the opioid effects and restore normal respiration.

Answer 159

There are four main features in tetralogy of Fallot. These include: Right ventricular outflow tract (RVOT) obstruction, which may be narrowing at, below, or above the pulmonary valve A large ventricular septal defect (VSD) The aorta overriding the ventricular septal defect Right ventricular hypertrophy (RVH) Left ventricular hypertrophy is not typically a feature in tetralogy of Fallot, so D is correct.

Answer 160

Correct Answer Explanation: Correct Answer: Endoscopic mucosal resection (EMR) followed by radiofrequency ablation (RFA) is indicated for Barrett’s esophagus with high-grade dysplasia (HGD), particularly when a nodular area is present. EMR facilitates removal of the nodular lesion and permits histopathological evaluation to exclude invasive carcinoma. Subsequently, RFA is employed to eradicate the remaining dysplastic Barrett’s epithelium, thereby reducing the risk of progression to esophageal adenocarcinoma. Incorrect Answer Explanations: Surveillance with repeat endoscopy is appropriate for Barrett’s esophagus without dysplasia or with low-grade dysplasia under certain circumstances, but HGD necessitates more aggressive therapy rather than mere monitoring, even though proton pump inhibitor therapy is continued. Immediate esophagectomy, while definitive, is reserved for cases where invasive carcinoma is confirmed or if endoscopic management fails. Given that the patient’s lesion is amenable to endoscopic evaluation and treatment, this approach is overly aggressive and associated with higher morbidity. Radiofrequency ablation alone may be considered when there is no nodularity. In the presence of a nodular lesion, EMR is necessary to obtain tissue for definitive histological diagnosis to exclude invasive cancer prior to RFA. Photodynamic therapy is an alternative ablation method for Barrett’s esophagus with dysplasia; however, it is less favored due to its adverse effects (such as photosensitivity and stricture formation) compared to the well tolerated RFA regimen.

Answer 161

Correct Answer Explanation: Correct Answer: RFA in patients with Barrett’s esophagus and low-grade dysplasia leads to sustained eradication of dysplasia with low recurrence rates over a 3- to 5-year period. Multiple studies have shown that the effective elimination of dysplasia through RFA significantly reduces the progression to high-grade dysplasia or adenocarcinoma, especially in patients initially diagnosed with low-grade dysplasia. Continued surveillance is important, but the overall prognosis remains favorable. Incorrect Answer Explanations: This choice is incorrect because although recurrence of dysplasia can occur after RFA, frequent recurrences within one year requiring multiple ablation sessions are not typical, particularly in patients with low-grade dysplasia. This option is incorrect as the progression to high-grade dysplasia and esophageal adenocarcinoma is significantly reduced following successful RFA in patients with low-grade dysplasia. This option is incorrect because the incidence of strictures post-RFA is low and most strictures can be managed effectively with endoscopic dilation. They do not significantly compromise long-term outcomes or cost-effectiveness. This answer is incorrect given that outcomes of RFA are not equivalent to those of esophagectomy. Esophagectomy is a more invasive procedure with higher morbidity and mortality, and it is generally reserved for more advanced disease.

Answer 162

Correct Answer: A. Extensor pollicis longus tendon rupture Explanation: The extensor pollicis longus (EPL) tendon is particularly vulnerable to rupture following a distal radial fracture, even if the fracture is undisplaced. The rupture often occurs due to ischemia, mechanical attrition, or inflammation associated with the healing process. It is commonly seen around 2–6 weeks after the initial injury. The classic presentation includes: • Pain at the wrist • Inability to extend the thumb (loss of EPL function) • Intact sensation (helping differentiate it from nerve injuries) Why not the other options? • B. Complex regional pain syndrome (CRPS) Type 1 – This would present with burning pain, allodynia, swelling, and skin changes, rather than an isolated thumb extension deficit. • C. Posterior interosseous nerve (PIN) injury – PIN injury causes finger and wrist drop but spares the sensory function. However, it typically results from direct trauma or compression rather than a simple cast immobilization. • D. Displaced fracture – A displaced fracture would typically cause deformity, swelling, or malalignment, rather than an isolated tendon rupture. • E. Radial nerve injury – A radial nerve injury would cause wrist drop and sensory deficits in the dorsal hand, which are absent in this case. Takeaway: EPL tendon rupture is a well-known complication of distal radial fractures and should be suspected when a patient presents with inability to extend the thumb weeks after injury. Surgical tendon transfer (e.g., Extensor indicis proprius to EPL) is often required for management.

Answer 163

The correct answer is: **C. lateral horn** The sympathetic relay occurs in the **lateral horn** of the spinal cord, specifically in the **intermediolateral cell column** (IML). This region is found in the thoracic and upper lumbar segments (T1-L2) of the spinal cord, where preganglionic sympathetic neurons are located. These neurons send their axons out through the ventral roots to synapse with postganglionic neurons in sympathetic ganglia.

Answer 164

The correct answer is: **A. T1** A **Pancoast tumor** (a type of lung cancer located at the apex of the lung) often affects the **T1 nerve root** and sometimes the **C8 nerve root**. The tumor can invade the brachial plexus, leading to symptoms such as pain, weakness, and atrophy in the affected arm, as well as **Horner's syndrome** (ptosis, miosis, and anhidrosis) due to involvement of the sympathetic chain. The T1 nerve root is most commonly affected because of its proximity to the tumor location.

Answer 165

The correct answer is: **B. I.V saline infusion** The patient has **hypercalcemia** (elevated calcium level of 3.7 mmol/L, normal range 2–2.5 mmol/L). The initial management of hypercalcemia, especially if symptomatic (e.g., abdominal pain, dehydration, or altered mental status), includes: 1. **Intravenous (I.V.) saline infusion**: This is the first-line treatment to correct dehydration and promote calcium excretion through the kidneys (via forced diuresis). 2. **Loop diuretics** (e.g., furosemide) may be added after rehydration to enhance calcium excretion. 3. **Bisphosphonates** (e.g., zoledronate or pamidronate) are used for long-term control of hypercalcemia, particularly in cases of malignancy-related hypercalcemia, but they are not the first step in acute management. 4. **Calcium gluconate** is used for **hypocalcemia**, not hypercalcemia. Thus, the immediate management for this patient is **I.V. saline infusion**.

Answer 166

The correct answer is: **B. 1 L of 0.9 % saline plus 1.5 L of 5 % dextrose** In the **postoperative period**, maintenance fluids are used to replace normal daily losses and maintain electrolyte balance. The standard maintenance fluid regimen typically includes: - **Water**: 25–30 mL/kg/day (approximately 2–2.5 L for a 70 kg adult). - **Sodium**: 1–2 mmol/kg/day. - **Potassium**: 1 mmol/kg/day. The choice of fluids should provide both **electrolytes** and **glucose** to meet these requirements. - **0.9% saline** provides sodium and chloride but no potassium or glucose. - **5% dextrose** provides free water and glucose but no electrolytes. - Combining **1 L of 0.9% saline** (to provide sodium) with **1.5 L of 5% dextrose** (to provide free water and glucose) is a common and appropriate regimen for postoperative maintenance fluid therapy. The other options are incorrect because: - **A**: 4% dextrose/0.18% saline provides insufficient sodium. - **C**: Hartmann's solution is more commonly used for fluid resuscitation rather than maintenance. - **D**: 2 L of 0.9% saline provides excessive sodium and no glucose. - **E**: 4% dextrose/0.18% saline provides insufficient sodium and is not typically used for maintenance.

Answer 167

The correct answer is: **B. Infiltration by 1% or 0.5% bupivacaine** In a patient with **flail chest** (a segment of the rib cage detached due to multiple rib fractures) and **pain on inspiration**, the primary management focuses on **pain control** to improve ventilation and prevent complications like atelectasis or pneumonia. - **Local anesthetic infiltration** (e.g., **1% or 0.5% bupivacaine**) is a good option for pain relief, as it provides longer-lasting analgesia compared to lignocaine. - **Epidural analgesia** is another effective option for pain management in flail chest, but it is not listed here. - **Chest drains** are not indicated in the absence of pneumothorax or hemothorax. - **Lignocaine** (option A) provides shorter-lasting pain relief compared to bupivacaine. Thus, the best choice among the options is **B. Infiltration by 1% or 0.5% bupivacaine**.

Answer 168

The correct answer is: **D. Intraventricular hemorrhage** A **preterm baby** who is **drowsy and floppy immediately post-partum** is most likely suffering from **intraventricular hemorrhage (IVH)**. This condition is common in preterm infants, particularly those born before 32 weeks of gestation, due to the fragility of the germinal matrix vasculature in the developing brain. - **Intraventricular hemorrhage** can lead to symptoms such as lethargy, hypotonia (floppiness), apnea, and seizures. - **Acute subdural hemorrhage** (A) and **extradural hemorrhage** (B) are more commonly associated with traumatic deliveries, such as those involving forceps or vacuum extraction, and are less likely in preterm infants. - **Subarachnoid hemorrhage** (C) can occur in newborns but is less common than IVH in preterm infants. Thus, the most likely diagnosis in this scenario is **D. Intraventricular hemorrhage**.

Answer 169

The most likely cause of a shiny, tense palm skin after a displaced wrist fracture is Regional Pain Syndrome (Complex Regional Pain Syndrome, CRPS). Explanation: CRPS is a condition that can develop after an injury, such as a wrist fracture, and is characterized by: • Shiny, tense skin • Pain out of proportion to the injury • Swelling and stiffness • Temperature changes (hot or cold) • Hyperalgesia and allodynia (increased pain sensitivity) This condition occurs due to dysregulated autonomic and inflammatory responses in the affected limb. Answer: A. Regional Pain Syndrome (CRPS) Other options: • B. Carpal Tunnel Syndrome: Usually presents with numbness, tingling, and weakness in the median nerve distribution but does not typically cause shiny or tense skin. • C. Dupuytren’s Contracture: Causes progressive palmar fibrosis and finger contractures, but it does not develop acutely after a fracture. • D. Hemarthrosis: Involves bleeding into a joint, typically causing joint swelling rather than changes in the skin texture. This scenario fits well with Complex Regional Pain Syndrome (CRPS), which can follow trauma such as a wrist fracture

Answer 170

The most accepted cause of thumb extension and adduction with loss of other movements following a fall on an outstretched hand is lunate dislocation. Answer: C. Lunate dislocation Explanation: Lunate dislocation can cause compression of the median nerve, leading to loss of opposition, flexion, and abduction of the thumb. The characteristic “spilled teacup sign” on lateral wrist X-ray is diagnostic of lunate dislocation. The dislocated lunate may impinge on the median nerve, affecting the thenar muscles except for the adductor pollicis (which is supplied by the ulnar nerve), leading to the described clinical picture. Why not the other options? • A. Hook of hamate fracture → Typically affects the ulnar nerve, leading to weakness of intrinsic hand muscles, not isolated thumb movement loss. • B. Distal radial fracture → Could cause median nerve compression (e.g., in Colles’ fracture), but is less likely to cause complete loss of thumb movement. • D. Scaphoid fracture → Presents with snuffbox tenderness and risks avascular necrosis, but does not typically cause the described motor deficit. • E. Monteggia fracture → Affects the radial nerve, which controls wrist and finger extension, rather than thumb function. This scenario is classic for median nerve compression secondary to lunate dislocation

Answer 171

The most likely cause of this patient’s condition is bladder rupture (Option E). Explanation: • The patient initially ignored the desire to urinate due to stress, leading to prolonged bladder distension. • After the stress resolved, he lost the urge to urinate, which suggests neurological or structural bladder dysfunction. • Examination findings include abdominal tenderness, distension, and an empty Foley catheter, which indicates that urine is not collecting as expected. • In the context of a previously distended bladder, a rupture is a serious concern, leading to urinary leakage into the peritoneal cavity. • Bladder rupture is often associated with pelvic trauma, but can also occur due to chronic overdistension, as seen in this case . Why Other Options Are Less Likely: • A. Blocked catheter – Would result in a full bladder and catheter obstruction, but here the catheter is empty. • B. Hypovolemia – Would not explain the empty bladder unless the patient was in severe shock, which is not described. • C. Bladder diverticulum – Can cause urinary retention or infections, but does not usually lead to acute bladder rupture or an empty catheter. • D. Ureteric stone – Would present with flank pain and hematuria, but not loss of bladder sensation or an empty catheter. Thus, bladder rupture (E) is the best answer.

Answer 172

The correct answer is: C) Acidophilic acinar cells and ductal cells Explanation: • Meckel’s diverticulum is a congenital anomaly that can contain heterotopic (ectopic) tissue, including gastric and pancreatic tissue. • Ectopic pancreatic tissue is composed mainly of exocrine acinar cells, ductal structures, and occasionally endocrine islet cells. • Acinar cells in the pancreas are acidophilic due to their high content of zymogen granules, which are rich in digestive enzymes like trypsinogen and amylase. • Basophilic acinar cells are not characteristic of pancreatic tissue. • Islets of Langerhans, which contain beta cells (insulin-secreting), are less commonly found in ectopic pancreatic tissue Thus, C) Acidophilic acinar cells and ductal cells is the most accurate description of the microscopic features.

Answer 173

B) Peripheral neuropathy Explanation: • Metronidazole is commonly used to treat pouchitis in patients with an ileoanal pouch. • A well-known side effect of long-term metronidazole use is peripheral neuropathy, which presents with paresthesia (numbness and tingling), weakness, and loss of sensation in the extremities. • The mechanism is thought to involve mitochondrial toxicity and nerve damage. Why Not the Other Options? • A) Ileoanal fibrosis – This is related to chronic inflammation or ischemia, not metronidazole. • C) Coagulopathy – Metronidazole does not significantly affect coagulation. • D) Ileovesical fistula – This is a complication of Crohn’s disease or post-surgical complications, not a drug side effect. • E) Pouchitis – This is an indication for metronidazole, not a side effect. Thus, Peripheral neuropathy (B) is the correct answer.

Answer 174

Answer: B. Hormonal manipulation Explanation: This patient has metastatic prostate cancer, as indicated by: • Back pain (suggesting bone metastases, common in prostate cancer) • Irregular, hard prostate on DRE (suggestive of malignancy) • Very high PSA (300 ng/ml) (normal is <4 ng/ml, indicating advanced disease) The first-line treatment for metastatic prostate cancer is hormonal manipulation (androgen deprivation therapy - ADT). This involves: • LHRH agonists (e.g., leuprolide, goserelin) or • Bilateral orchidectomy (surgical castration) • Anti-androgens (e.g., bicalutamide) may be added to prevent testosterone flare Why not the other options? • A. Bladder neck incision → Used for benign prostatic hyperplasia (BPH), not cancer. • C. Radical prostatectomy → Only for localized prostate cancer; not suitable for metastatic disease. • D. TURP (Transurethral Resection of Prostate) → Used for urinary obstruction in BPH, but not curative for prostate cancer. • E. Watchful waiting → Not appropriate for metastatic prostate cancer with symptoms. Hormonal therapy is the standard first-line treatment in patients with advanced/metastatic prostate cancer

Answer 175

Answer: Sjögren’s Syndrome Explanation: This 40-year-old woman with long-standing rheumatoid arthritis (RA) presents with: • Dry mouth (xerostomia) • Bilateral parotid gland swelling • Symptoms improving transiently with steroids These features are highly suggestive of Sjögren’s syndrome, an autoimmune condition that commonly occurs in patients with rheumatoid arthritis. It primarily affects the exocrine glands, leading to dry mouth, dry eyes (keratoconjunctivitis sicca), and salivary gland enlargement. Why not the other options? • Adenoid cystic carcinoma → A malignant tumor of the salivary glands, usually presents with painful, persistent swelling and facial nerve involvement. It does not improve with steroids. • Sarcoidosis → Can cause bilateral parotid gland swelling (Heerfordt syndrome) but is more associated with pulmonary symptoms, uveitis, and hypercalcemia. It is less likely in a patient with rheumatoid arthritis and dry mouth. Conclusion: Sjögren’s syndrome is the most likely diagnosis in this patient with RA, dry mouth, and bilateral parotid swelling. Steroids can temporarily improve symptoms but are not the mainstay of treatment.

Answer 176

Answer: D. Cholesteatoma Explanation: This 34-year-old woman presents with: • Persistent offensive ear discharge • Hearing loss (40 dB) These features are highly suggestive of cholesteatoma, a destructive lesion of the middle ear caused by the abnormal growth of keratinizing squamous epithelium within the middle ear and mastoid. Key Features of Cholesteatoma: • Chronic ear discharge (foul-smelling, persistent, and often painless) • Progressive conductive hearing loss (~40 dB loss is common) • Complications: Can erode ossicles, leading to significant hearing loss, and may cause facial nerve palsy, labyrinthine fistula, or intracranial infections. Why not the other options? • A. Acoustic neuroma → Causes sensorineural hearing loss, usually unilateral, with associated tinnitus and sometimes imbalance. • B. Preauricular sinus → Can cause recurrent localized infections, but does not lead to persistent ear discharge or hearing loss. • C. Acute suppurative otitis media → Presents with fever, ear pain, and transient conductive hearing loss, but it does not cause persistent discharge or progressive hearing loss. • E. Otitis externa → Causes ear pain, swelling, and discharge, but hearing loss is not usually significant (mild conductive loss due to canal blockage). Conclusion: Cholesteatoma is the best answer given the persistent offensive ear discharge and significant conductive hearing loss. Early referral to ENT is essential for surgical management to prevent complications.

Answer 177

The correct answer is: B. Plantar aspect of the foot Explanation: The patient likely has compartment syndrome or nerve compression due to prolonged casting of the tibia, leading to tibial nerve dysfunction. The tibial nerve supplies the muscles responsible for plantar flexion (e.g., gastrocnemius, soleus, and tibialis posterior) and provides sensory innervation to the plantar aspect of the foot. Thus, damage to the tibial nerve results in: • Motor deficit: Weakness or inability to plantar flex. • Sensory deficit: Loss of sensation on the plantar surface of the foot. Let’s go through each option systematically: A. Dorsum of the foot → Incorrect • The dorsum of the foot is supplied by the superficial peroneal nerve, except for the 1st web space, which is supplied by the deep peroneal nerve. • Since the tibial nerve is affected, the dorsum of the foot would not lose sensation, making this option incorrect. C. 1st web space → Incorrect • As explained earlier, the 1st web space is supplied by the deep peroneal nerve, not the tibial nerve. • The patient’s main issue is plantar flexion weakness, which indicates tibial nerve involvement, ruling out this option. D. Dorsum of the foot except the 1st web space → Incorrect • The superficial peroneal nerve supplies most of the dorsum of the foot, except the 1st web space (deep peroneal nerve). • Since the tibial nerve does not supply the dorsum of the foot, there will be no sensory loss in this region, making this answer incorrect. E. None of the above → Incorrect • There will be sensory loss, specifically on the plantar aspect of the foot, so this option is incorrect. Final Answer: B. Plantar aspect of the foot (Correct) • The tibial nerve supplies sensory innervation to the plantar surface of the foot and motor innervation to the muscles responsible for plantar flexion. • Injury to the tibial nerve (e.g., compression from prolonged casting) leads to loss of plantar flexion and sensory loss in the plantar aspect of the foot.

Answer 178

A) Avascular necrosis. Explanation: Avascular necrosis (AVN) is a well-known complication following fixation of a displaced subcapital femoral neck fracture. The blood supply to the femoral head is mainly provided by the medial circumflex femoral artery, which can be disrupted in such fractures. If the femoral head loses its blood supply, it undergoes necrosis, leading to collapse and subsequent arthritis, which presents with pain and restricted hip movement. • Osteoarthritis (B) can occur as a late consequence of AVN but typically develops over a longer period. • Hip dislocation (C) is uncommon following internal fixation of a femoral neck fracture. • Synovitis (D) is an inflammatory process that usually follows an acute insult rather than a delayed complication. • Osteosarcoma (E) is rare and unlikely in this scenario. Thus, the delayed onset of pain and restricted movement strongly suggests AVN as the primary pathology. osteoarthritis (OA) can develop as a secondary consequence of avascular necrosis (AVN), and a two-year timeframe is sufficient for degenerative changes to occur. However, the key factor in this scenario is the primary pathology leading to the symptoms. Why Avascular Necrosis (AVN) is still the best answer: 1. AVN is a direct complication of femoral neck fracture fixation, especially in displaced subcapital fractures, due to disruption of the medial circumflex femoral artery. 2. Hip pain and restricted movement are hallmarks of AVN, which often progresses to joint collapse before osteoarthritis sets in. 3. Two years is within the typical timeframe for AVN progression, leading to secondary osteoarthritis, but the initial cause remains AVN. Could it be Osteoarthritis (OA)? • Yes, but OA in this case would likely be secondary to AVN, meaning AVN is still the primary pathology. • If the question specifically mentioned chronic gradual worsening over many years (rather than a more sudden onset of symptoms after a fracture fixation), OA could be a stronger contender. Conclusion: The most precise answer remains AVN because it precedes OA in cases of post-fixation complications. If left untreated, AVN leads to secondary osteoarthritis, but the primary issue in this patient’s timeline is AVN itself.

Answer 179

Correct Answer: A. Hyperparathyroidism Explanation: The most common metabolic cause of recurrent renal stones is primary hyperparathyroidism. This condition leads to hypercalcemia and hypercalciuria, which promote the formation of calcium-based kidney stones (typically calcium oxalate or calcium phosphate). Key Features Suggesting Hyperparathyroidism: • Recurrent renal stones (especially calcium oxalate) • Elevated serum calcium levels • Elevated or inappropriately normal parathyroid hormone (PTH) levels • Reduced serum phosphate (due to PTH effects on the kidneys) Why Not the Other Options? • B. Familial hyperoxaluria – Rare genetic disorder causing excessive oxalate production, leading to severe early-onset renal stones and nephrocalcinosis. Usually diagnosed in childhood. • C. Idiopathic cystinuria – A genetic disorder causing defective renal transport of cystine, leading to cystine stones. These stones are hexagonal and are diagnosed with the cyanide-nitroprusside test. • D. Gout – Gout leads to uric acid stones, but the most common type of renal stone is calcium-based, making hyperparathyroidism the more likely answer. • E. Pseudogout – Pseudogout is associated with calcium pyrophosphate deposition disease (CPPD), typically affecting joints rather than forming urinary stones. Takeaway: If a patient presents with recurrent renal stones, especially calcium-based, hyperparathyroidism should be suspected first and confirmed with calcium and PTH levels.

Answer 180

The correct answer is: Stable cells. Explanation: Liver regeneration after resection occurs due to the proliferation of hepatocytes, which are classified as stable cells. • Stable cells (also called quiescent cells) are normally in the G0 phase of the cell cycle but can re-enter the cell cycle in response to injury or loss of tissue, as seen in liver resection. • Hepatocytes have a remarkable capacity for regeneration, allowing the liver to restore its mass after partial resection. Why Not the Other Options? • Labile cells: These continuously divide and are found in tissues like the skin, bone marrow, and gastrointestinal epithelium, but not in the liver. • Permanent cells: These cannot regenerate (e.g., neurons, cardiac myocytes). Liver cells can regenerate, so this is incorrect. • Stem cells: While liver stem cells (oval cells) exist, normal liver regeneration primarily occurs through hepatocyte proliferation, not stem cell activation. • Stellate cells: These are involved in liver fibrosis and vitamin A storage, not regeneration. Key Concept: Liver regeneration is unique because it is primarily driven by mature hepatocytes (stable cells), unlike other organs that rely on stem cells for repair.

Answer 181

The correct answer is: Sideroblastic anemia. Explanation: A Prussian blue stain is used to detect iron deposits in red blood cells. The characteristic finding of ringed sideroblasts (iron-laden mitochondria forming a ring around the nucleus of erythroblasts) is diagnostic of sideroblastic anemia. Why Not the Other Options? • Chronic iron deficiency anemia → Would show hypochromic, microcytic RBCs with no iron deposits on Prussian blue stain (iron is deficient). • B12 deficiency anemia → Leads to megaloblastic anemia with hypersegmented neutrophils, not iron-stained sideroblasts. • Aplastic anemia → Characterized by pancytopenia and a hypocellular bone marrow, but does not involve iron-laden RBCs. • Myelofibrosis → Shows tear-drop RBCs and leukoerythroblastic blood picture, not sideroblasts. Key Concept: • Sideroblastic anemia can be hereditary (e.g., ALAS2 mutation) or acquired (e.g., alcohol, lead poisoning, myelodysplastic syndrome). • Ringed sideroblasts are due to defective heme synthesis, leading to iron accumulation in mitochondria. Thus, sideroblastic anemia is the most likely diagnosis in this case.

Answer 182

The correct answer is: C) Lysine Explanation: Tranexamic acid (TXA) is a synthetic analogue of lysine that works as an antifibrinolytic agent by competitively inhibiting the activation of plasminogen to plasmin, thereby preventing fibrin degradation and promoting clot stability. Mechanism of Action: • Plasminogen contains lysine-binding sites that help it bind to fibrin for clot breakdown. • TXA competes with lysine for binding to plasminogen, blocking fibrinolysis and stabilizing clots. Why Not the Other Options? • Glutamate (A) → Important in neurotransmission and metabolism but not directly related to fibrinolysis. • Valine (B) → A branched-chain amino acid involved in protein synthesis, not antifibrinolysis. • Alanine (D) → Plays a role in gluconeogenesis but has no known antifibrinolytic properties. Clinical Uses of TXA: • Trauma and surgery (reduces bleeding) • Postpartum hemorrhage • Heavy menstrual bleeding • Hereditary angioedema Thus, TXA is a lysine analogue that prevents excessive bleeding by inhibiting fibrinolysis.

Answer 183

The correct answer is: Transthyretin (ATTR) amyloid. Explanation: In a 50-year-old male with ischemic heart disease, the most common form of cardiac amyloidosis is due to transthyretin (TTR) amyloid deposition. Types of Cardiac Amyloidosis: 1. Transthyretin (ATTR) amyloidosis • Can be wild-type (senile systemic amyloidosis) or hereditary (mutant TTR gene). • Wild-type ATTR occurs in older adults and primarily affects the heart, leading to restrictive cardiomyopathy and heart failure with preserved ejection fraction (HFpEF). • Mutant ATTR is inherited and can cause familial amyloid cardiomyopathy (FAC). 2. AL amyloidosis (Immunoglobulin Light Chain Amyloidosis) • Caused by monoclonal plasma cell dyscrasia (e.g., multiple myeloma). • Also affects the kidneys, liver, nerves, and heart (but less common than ATTR in isolated cardiac cases). 3. AA amyloidosis • Due to chronic inflammatory conditions (e.g., rheumatoid arthritis, tuberculosis). • Rarely affects the heart significantly. 4. B2-microglobulin amyloidosis • Seen in patients on long-term dialysis. • Mainly affects joints and bones, not the heart. Why ATTR is the Most Common in This Case? • Age (50 years old) suggests wild-type ATTR or early hereditary ATTR. • Ischemic heart disease and restrictive cardiomyopathy are commonly associated with TTR amyloid deposition in the heart. Conclusion: Transthyretin amyloidosis (ATTR) is the most common form of cardiac amyloidosis, especially in older adults with ischemic heart disease or heart failure with preserved ejection fraction (HFpEF).

Answer 184

The scenario described suggests that the patient may have developed a **pneumothorax** following the removal of the subclavian line. This is a known complication of central line removal, particularly with subclavian lines, as air can enter the pleural space, leading to lung collapse and sudden hypoxia. The **best next step** is: **B) Put the patient in the left lateral decubitus position.** ### Explanation: - **Left lateral decubitus position**: If a pneumothorax is suspected, placing the patient in the left lateral decubitus position (if the subclavian line was on the right side) can help trap air in the apex of the lung, preventing further compromise of the mediastinum and cardiovascular collapse. This is a temporary measure while preparing for definitive treatment (e.g., chest tube insertion). ### Why not the other options? - **A) Prone position**: This is used for severe ARDS to improve oxygenation but is not appropriate for a suspected pneumothorax. - **C) Trendelenburg position**: This position is used for hypotension or to facilitate central line insertion but is not helpful in a pneumothorax. - **D) High-flow oxygen**: While oxygen supplementation is important, it does not address the underlying issue of a pneumothorax. Definitive treatment (e.g., chest tube) is required. ### Immediate actions: 1. Confirm the diagnosis with a **chest X-ray** or **point-of-care ultrasound**. 2. Prepare for **chest tube insertion** if a pneumothorax is confirmed. 3. Monitor the patient closely for signs of tension pneumothorax (e.g., hypotension, tracheal deviation, absent breath sounds), which is a life-threatening emergency.

Answer 185

The correct answer is: C) Radical debridement. Explanation: This patient has signs of necrotizing soft tissue infection (NSTI), likely necrotizing fasciitis, which presents with: • Erythematous, foul-smelling wound • Skin blisters (bullae) and crepitus (gas-producing organisms like Clostridium perfringens or polymicrobial infections) • Rapid progression of infection Best Initial Course of Action: Radical surgical debridement (C) is the most important and life-saving intervention. • Removes necrotic, infected tissue to control the spread of the infection. • Delaying debridement increases mortality because NSTI progresses rapidly. Why Not the Other Options? • A) Antibiotic therapy → Essential but not sufficient as monotherapy. Antibiotics alone do not stop the spread of necrotic tissue. • B) Removal of sutures → May expose the infection, but it does not treat the underlying necrotizing process. • D) Percutaneous drainage → Not appropriate for deep soft tissue infections; radical debridement is required. Additional Management: • Empirical broad-spectrum IV antibiotics (e.g., carbapenem + clindamycin + vancomycin) after surgical debridement. • Hemodynamic support if septic shock develops. • Possible repeat debridements if needed. • Hyperbaric oxygen therapy (HBO) in select cases. Conclusion: Immediate radical debridement (C) is the priority because necrotizing fasciitis is a rapidly progressive and life-threatening condition. Delaying surgery significantly increases mortality.

Answer 186

The most likely organism responsible for septic arthritis in a young, sexually active patient is Neisseria gonorrhoeae. This bacterium is known to cause disseminated gonococcal infection, which can lead to septic arthritis. Other common causes of septic arthritis include Staphylococcus aureus, which is the most frequent pathogen overall, and Streptococcus species. However, in the context of a sexually active patient, N. gonorrhoeae is the primary suspect.

Answer 187

The correct answer is: **A. Median nerve** ### Explanation: A supracondylar humeral fracture, particularly the extension type (which is more common), can result in injury to the **median nerve**. This nerve is at greatest risk due to its proximity to the fracture site and the potential for displacement of the fracture fragments. The median nerve can be compressed or stretched as it passes anteriorly near the elbow joint. Other nerves, such as the **ulnar nerve** and **radial nerve** (including its branches like the posterior interosseous nerve), are less commonly injured in this type of fracture. The **anterior interosseous nerve**, a branch of the median nerve, can also be affected but is less likely compared to the main median nerve trunk. Thus, the **median nerve** is the most at risk in a supracondylar humeral fracture.

Answer 188

The Glasgow Coma Score (GCS) is calculated based on three components: • Eye Response (E): • Opens spontaneously: 4 • Opens to verbal command: 3 • Opens to pain: 2 • No response: 1 • Verbal Response (V): • Oriented: 5 • Confused: 4 • Inappropriate words: 3 • Incomprehensible sounds: 2 • No response: 1 • Motor Response (M): • Obeys commands: 6 • Localizes pain: 5 • Withdraws from pain: 4 • Abnormal flexion (decorticate): 3 • Abnormal extension (decerebrate): 2 • No response: 1 For the given case: • Eye response: Opens to pain → Score 2 • Verbal response: Incomprehensible sounds → Score 2 • Motor response: Localizes pain → Score 5 Total GCS = 2 + 2 + 5 = 9/15 Thus, the correct answer is C. 9

Answer 189

The correct answer is: D. GERD (Gastroesophageal Reflux Disease) Explanation: A 4-month-old child with failure to thrive, recurrent chest infections, and dyspnea that worsens when lying flat (nocturnal symptoms) strongly suggests gastroesophageal reflux disease (GERD). • GERD in infants can lead to aspiration of refluxed gastric contents, which can cause recurrent chest infections and respiratory distress. • Symptoms often worsen when lying flat, as gravity no longer helps keep stomach contents down. • Nighttime reflux can cause disturbed sleep and frequent awakenings. Why not the other options? • Tetralogy of Fallot (TOF) (A): Presents with cyanotic spells, worsened with exertion, not specifically related to lying flat. • Congenital diaphragmatic hernia (B): Usually diagnosed at birth or in the neonatal period with severe respiratory distress. • Asthma (C): Can cause nocturnal symptoms, but failure to thrive is less common in early infancy. Thus, GERD is the most likely diagnosis in this case.

Answer 190

The correct answer is: A. Aortic dissection Explanation: This case describes a pregnant woman (36 weeks gestation) with sudden chest pain and a family history of early cardiac death. Given her tall, slim build, this suggests a possible connective tissue disorder (e.g., Marfan syndrome), which is a major risk factor for aortic dissection. Key Features Supporting Aortic Dissection: 1. Sudden onset chest pain – A classic symptom. 2. Pregnancy – Increases the risk of aortic dissection, particularly in the third trimester due to hormonal effects on vascular integrity. 3. Tall, slim habitus – Suggestive of Marfan syndrome, a known risk factor for aortic root dilatation and dissection. 4. Family history of sudden cardiac death – Could indicate a genetic predisposition to aortic pathology. Why Not the Other Options? • Myocardial infarction (MI) (B): Rare in young women without major risk factors (e.g., hypertension, diabetes, smoking). Also, pregnancy-related MI is more likely in the peripartum period. • Panic attack (C): Could cause chest pain but wouldn’t explain the family history of sudden death or the association with pregnancy. • Puerperal psychosis (D): Occurs postpartum, not during pregnancy. • Pulmonary thromboembolism (E): While pregnancy increases venous thromboembolism (VTE) risk, there are no signs of dyspnea, hypoxia, or hemoptysis in this patient. Final Thought: Given the clinical context and risk factors, aortic dissection should be the primary concern until proven otherwise. Immediate imaging (e.g., echocardiography, CT angiography) is required to confirm the diagnosis.

Answer 191

Correct Answer: A. Ipsilateral side (same side as the dilated pupil) Explanation: • A dilated pupil in the context of head trauma suggests uncal herniation, which occurs due to compression of the oculomotor nerve (CN III) by the expanding hematoma. • Even though there are bilateral extradural hematomas, the one causing the herniation signs (pupil dilation) should be prioritized. • Burr hole placement should begin on the ipsilateral side to rapidly decompress the mass effect and relieve pressure on the brainstem. Why Not the Other Options? • B. Contralateral side – The contralateral hematoma may also need evacuation, but the first priority is the side showing clinical signs of herniation. • C. Vertex – The vertex is not a typical location for burr holes in extradural hematomas, which are mostly temporal or parietal. • D. Midline suboccipital region – This approach is used for posterior fossa decompression, not for treating supratentorial EDH. Key Takeaway: In cases of bilateral extradural hematomas, the first burr hole should be placed on the side of the dilated pupil, as it indicates impending herniation and urgent decompression is needed.

Answer 192

The correct answer is: D. Radiotherapy Explanation: This 72-year-old man with renal carcinoma and metastatic bone pain in the humerus requires effective pain relief and local tumor control. Radiotherapy is the most appropriate treatment for metastatic bone pain because: 1. Pain relief – Radiation reduces pain by decreasing tumor burden and inflammation. 2. Prevention of pathological fractures – By stabilizing the affected bone. 3. Long-term control – Helps in palliating symptoms effectively. Why Not the Other Options? • Nerve block (A): Used for localized, refractory pain but not first-line for bone metastases. • NSAIDs (B) & Paracetamol (C): May provide mild relief but are insufficient for metastatic bone pain, which is often severe. • Slow-release morphine (E): Used for cancer pain, but should be combined with radiotherapy for better long-term relief. Final Thought: Radiotherapy is the best first-line treatment for metastatic bone pain in this case, providing both pain relief and disease control.

Answer 193

The correct answer is: A) LMWH and stockings Explanation: This 52-year-old smoker undergoing elective colon resection is at high risk for venous thromboembolism (VTE) due to: • Major abdominal surgery • Smoking (a risk factor for hypercoagulability) The most appropriate thromboprophylaxis in this case is a combination of Low Molecular Weight Heparin (LMWH) and graduated compression stockings. Why this choice? 1. LMWH – Effectively reduces the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE) in surgical patients. 2. Graduated compression stockings – Help improve venous return, reducing stasis in lower limbs. 3. Combination therapy is recommended – Especially for major abdominal surgeries per NICE guidelines. Why Not the Other Options? • LMWH alone (B): Good but adding stockings provides extra protection. • IVC filter (C): Only indicated in patients with contraindications to anticoagulation or recurrent VTE despite anticoagulation. • Oral anticoagulants (D): Not used for surgical thromboprophylaxis due to delayed onset of action and risk of bleeding. • None of the above (E): Incorrect, as thromboprophylaxis is essential in major abdominal surgery. Final Thought: For elective colon resection, LMWH + stockings is the best evidence-based approach to prevent perioperative VTE.

Answer 194

The correct answer is: A. Lower trunk of the brachial plexus Explanation: This patient has numbness on the ulnar side of the hand (little finger + both sides of the ring finger) and weakness in the abductor pollicis brevis and first dorsal interosseous muscles. This suggests an injury affecting both the ulnar and median nerve distributions, which points to a lesion at the lower trunk of the brachial plexus (C8-T1 roots). Key Features Supporting Lower Trunk Injury: • Sensory loss: Ulnar border of the hand (C8-T1 dermatome). • Motor weakness: • First dorsal interosseous (ulnar nerve, C8-T1). • Abductor pollicis brevis (median nerve, C8-T1). • Mechanism of injury: • Thoracotomy can cause traction or compression of the lower trunk of the brachial plexus. Why Not the Other Options? • Median nerve (B): Would not explain ulnar-sided sensory loss or first dorsal interosseous weakness (which is innervated by the ulnar nerve). • Middle trunk of the brachial plexus (C): Involves C7, which primarily affects radial nerve muscles (e.g., triceps, wrist extensors), not the ulnar border of the hand. • Ulnar nerve (D): Would cause weakness in the first dorsal interosseous muscle but not abductor pollicis brevis, which is supplied by the median nerve. • Upper trunk of the brachial plexus (E): Affects C5-C6, causing shoulder abduction and elbow flexion weakness (Erb’s palsy-like features), not ulnar-sided sensory loss. Final Thought: This presentation is highly suggestive of a lower trunk (C8-T1) brachial plexus injury, most likely due to traction or compression during thoracotomy.

Answer 195

The correct answer is D. Transverse cervical ligaments. Here's why: * Transverse cervical ligaments (also known as cardinal ligaments): These are the primary supports for the uterus, preventing it from prolapsing. They extend from the cervix and upper vagina to the lateral pelvic walls. * Mesometrial part of the broad ligament: While the broad ligament provides some support, the mesometrium (the part attached to the uterus) is relatively loose and doesn't offer the same level of direct, rigid support as the cardinal ligaments. * Mesosalpingial part of the broad ligament: This portion of the broad ligament supports the fallopian tubes, not primarily the uterus. * Round ligament: These ligaments help maintain the anteverted position of the uterus, but they provide minimal vertical support. * Transverse perineal muscles: These muscles support the pelvic floor, which indirectly aids in pelvic organ support, but they do not provide direct support to the uterus itself, like the cardinal ligaments do. In a multiparous woman with pelvic discomfort and a feeling of "something coming down," the most likely issue is uterine prolapse, which directly implicates the primary uterine supports, the cardinal ligaments.

Answer 196

The correct answer is: D. Hydrocele Explanation: A 3-year-old boy with intermittent unilateral scrotal swelling is most likely to have a communicating hydrocele. Key Features of a Communicating Hydrocele: • Fluctuating swelling – Appears and disappears due to fluid movement between the peritoneal cavity and tunica vaginalis. • Transillumination positive – When light is shined through, it appears translucent. • Associated with a patent processus vaginalis – This allows peritoneal fluid to move into the scrotum, making it intermittent. Why Not the Other Options? • Direct inguinal hernia (A): Rare in children. More common in adults due to weakened abdominal wall. • Epididymal cyst (B): Usually occurs in older individuals, not in young children. It is also non-fluctuating. • Femoral hernia (C): More common in women and presents as a groin swelling below the inguinal ligament, not in the scrotum. • Varicocele (E): More common in adolescents, typically on the left side, and described as a “bag of worms” that does not fluctuate significantly. Final Thought: A communicating hydrocele is the most likely cause of intermittent scrotal swelling in a 3-year-old. It is due to a patent processus vaginalis and may resolve spontaneously, but persistent cases might require surgical repair (herniorrhaphy).

Answer 197

The correct answer is: B. FEV1 < 1L Explanation: Forced Expiratory Volume in 1 second (FEV1) < 1L is the most important predictor of postoperative morbidity and mortality in patients undergoing surgery, particularly thoracic and major abdominal surgeries. Why is FEV1 important? • FEV1 < 1L is associated with high risk of respiratory complications such as pneumonia, prolonged ventilation, and respiratory failure. • It is a strong predictor of postoperative respiratory function, especially in lung resection or general anesthesia. • In patients undergoing lung surgery (e.g., lobectomy, pneumonectomy), FEV1 is used to determine if they have enough functional lung reserve to tolerate surgery. Why Not the Other Options? • A. Confronted flow volume loop: Not the best single predictor; mainly used to assess upper airway obstruction. • C. FEV1/FVC > 90%: Suggests restrictive lung disease, but not a key predictor of surgical risk. • D. Tidal volume = 1500: Tidal volume varies and is not a strong predictor of postoperative complications. • E. Increased residual volume: Common in obstructive lung diseases (e.g., COPD) but does not predict postoperative mortality as well as FEV1 < 1L. Final Thought: For preoperative pulmonary risk assessment, FEV1 < 1L is the best predictor of poor surgical outcomes, especially in patients undergoing lung or major abdominal surgery.

Answer 198

The correct answer is: A) Microvascular free flap Explanation: A 33-year-old man with complete nasal loss due to a dog bite requires complex nasal reconstruction. The best option is a microvascular free flap, which provides: 1. Adequate tissue volume and vascular supply – Essential for functional and aesthetic reconstruction. 2. Best contour and durability – Helps restore nasal shape and structural integrity. 3. Long-term viability – Compared to skin grafts, free flaps integrate better and are less prone to contracture. Why Not the Other Options? • Split-thickness skin graft (STSG) (B): Too thin, lacks structural support, and prone to contraction. • Full-thickness skin graft (FTSG) (C): May provide better coverage than STSG, but lacks volume and support. • Pedicle flap (D): Limited mobility and may not provide sufficient tissue bulk for total nasal reconstruction. • Secondary intention (E): Not appropriate for large tissue defects, as healing would be prolonged and cosmetically poor. Final Thought: For total nasal loss, a microvascular free flap (e.g., radial forearm, anterolateral thigh, or forehead flap) is the gold standard for functional and aesthetic nasal reconstruction.

Answer 199

The best management for this patient, who has a pneumothorax with a fluid level (likely a hemopneumothorax due to the stab wound), is: **D. Chest drain without suction** ### Explanation: - **Pneumothorax with fluid level**: This indicates the presence of both air and blood (or other fluid) in the pleural space, which is consistent with a traumatic injury like a stab wound. - **Chest drain (tube thoracostomy)**: This is the standard treatment for traumatic pneumothorax, especially when there is associated hemothorax (blood in the pleural space). The chest tube allows for the evacuation of both air and fluid, helping to re-expand the lung. - **Without suction**: Initially, a chest drain is placed without suction, as suction is not routinely required and can sometimes worsen bleeding or cause re-expansion pulmonary edema. If the lung does not re-expand adequately, suction can be added later. ### Why not the other options? - **A. Chest drain with suction**: Suction is not typically used initially unless the lung fails to re-expand. - **B. Needle decompression**: This is a temporary measure for tension pneumothorax, not for a stable pneumothorax with fluid. - **C. Thoracentesis**: This is used for diagnostic or therapeutic removal of fluid but does not address the pneumothorax effectively. - **E. None of the above**: A chest drain is the correct management. Thus, the best answer is **D. Chest drain without suction**.

Answer 200

Correct Answer: A. Quadriceps tendon rupture Explanation: A quadriceps tendon rupture is a common injury in patients with anticoagulant therapy, chronic kidney disease, diabetes, or previous steroid use. It typically presents with: • Swelling above the patella (suprapatellar region) • Inability to fully extend the knee • A palpable gap above the patella • Patella baja (low-lying patella) on imaging Since the quadriceps tendon is essential for active knee extension, rupture results in significant weakness or complete loss of extension. Why Not the Other Options? • B. Patellar tendon rupture – Would cause swelling below the patella and patella alta (high-riding patella) rather than suprapatellar swelling. • C. Prepatellar bursitis – Causes localized anterior swelling but does not typically impair knee extension. • D. Hemarthrosis – Common in anticoagulated patients but would cause generalized knee swelling without a specific loss of extension. • E. Meniscal tear – Can cause joint swelling and pain, but does not typically result in sudden inability to extend the knee unless associated with a locked knee (bucket-handle tear). Takeaway: A quadriceps tendon rupture should be suspected in anticoagulated patients with suprapatellar swelling and an inability to extend the knee. Urgent orthopedic evaluation and surgical repair are usually required.

Answer 201

Correct Answer: A. Adult Respiratory Distress Syndrome (ARDS) Explanation: This patient presents with acute hypoxemia, tachycardia, hypotension, and bilateral pulmonary opacities following major surgery (abdominal aortic aneurysm repair). The most likely cause is Acute Respiratory Distress Syndrome (ARDS), a severe inflammatory lung injury often triggered by major surgery, sepsis, or shock. Key Features of ARDS: • Acute onset respiratory distress • Severe hypoxemia (PaO₂ remains low despite high oxygen administration) • Bilateral pulmonary infiltrates on chest X-ray (“white-out” lungs) • Non-cardiogenic pulmonary edema (PAWP ≤ 18 mmHg, though some variation exists) Why Not the Other Options? • B. Heart failure – Would cause similar bilateral infiltrates but typically presents with elevated pulmonary artery wedge pressure (PAWP > 18 mmHg). This patient’s PAWP is borderline but not markedly elevated. • C. Pulmonary embolism (PE) – Can cause hypoxia and tachycardia, but it rarely presents with diffuse bilateral lung infiltrates. A PE is more likely if there were sudden pleuritic chest pain and clear lung fields on X-ray. • D. Lobar pneumonia – Would typically show a localized consolidation rather than diffuse opacities. Fever and productive cough would also be more prominent. • E. Aspiration pneumonia – Would present with localized infiltrates, often in the dependent lung segments, and typically occurs after vomiting or altered consciousness. Takeaway: ARDS should be suspected in any critically ill post-surgical patient with hypoxemia, bilateral pulmonary infiltrates, and no clear signs of cardiogenic pulmonary edema. Prompt management includes lung-protective ventilation with low tidal volumes, PEEP, and supportive care.

Answer 202

The correct answer is A) Thoracoacromial artery. Here's why: * Sternal Dehiscence and CABG: Sternal dehiscence, a separation of the sternum after a median sternotomy (common in CABG), disrupts the primary blood supply to the sternum, which is normally provided by the internal thoracic arteries. * Muscle Flap Repair: Muscle flap repair involves transferring a muscle with its blood supply to the affected area to provide vascularized tissue for healing. The pectoralis major muscle is frequently used in sternal wound repair. The blood supply of the pectoralis major muscle is the thoracoacromial artery. Therefore the blood supply to the sternum, after a muscle flap repair using the pectoralis major muscle, will be supplied by the thoracoacromial artery. * Why the other options are incorrect: * B) Internal thoracic artery: These arteries are the primary blood supply to the sternum but are often compromised during CABG and subsequent debridement. * C) Intercostal arteries: While they provide some collateral blood supply to the chest wall, they are not the primary source after a muscle flap repair. * D) Lateral thoracic artery: This artery supplies the lateral chest wall and is not the dominant blood supply to the sternum or the pectoralis major muscle.

Answer 203

Correct Answer: C) Total Parenteral Nutrition (TPN). Explanation: In the setting of a small contained oesophageal perforation, the primary concern is preventing further contamination while ensuring adequate nutrition. The approach to management depends on the severity of the perforation: • Small contained leaks with minimal symptoms can sometimes be managed conservatively. • Larger or uncontained leaks may require surgical intervention. Nutritional Strategy: • TPN (Total Parenteral Nutrition) is the best choice in this case because it allows complete bowel rest, preventing further oesophageal contamination and promoting healing. • Nil by mouth (NBM) and IV fluids alone (Option A) would not provide adequate nutrition for healing. • Sips orally (Option B) could worsen the leak by increasing intraoesophageal pressure. • Nasogastric feeding (Option D) or PEG tube feeding (Option E) is contraindicated in acute oesophageal perforations, as they can exacerbate the leak and delay healing. Conclusion: TPN provides the safest and most appropriate nutrition in this case, allowing healing without further oesophageal stress.

Answer 204

Correct Answer: B) Pituitary apoplexy** **Explanation:** **Pituitary apoplexy** is caused by **acute hemorrhage or infarction of a pituitary tumor**, leading to: - **Sudden severe headache** (due to meningeal irritation). - **Vomiting** (increased ICP). - **Potential visual/ocular palsy** (compression of optic chiasm/cavernous sinus). Other options: - **A) Hydrocephalus**: Rare with pituitary tumors unless obstructing 3rd ventricle. - **C) Meningitis**: Would feature fever/nuchal rigidity. - **D) Cavernous sinus thrombosis**: Presents with fever, proptosis, and cranial nerve palsies.

Answer 205

*Correct Answer:** **C) Discharge with a responsible adult** **Explanation:** The patient has a **mild head injury (GCS 13–15)** with **rapid improvement to GCS 15**, indicating low risk for complications (e.g., intracranial hemorrhage). Discharge with supervision is appropriate if: - No focal deficits. - No worsening symptoms. - Reliable follow-up. Other options: - **A) CT head**: Indicated if GCS <13, focal deficits, or high-risk features (e.g., vomiting, anticoagulation). - **B) Admission**: Needed if GCS not improving or concerning symptoms persist. - **D) Neurosurgical referral**: Reserved for significant pathology on imaging.

Answer 206

Correct Answer:** **C) Cemented total hip replacement (THR)** **Explanation:** For **active, elderly patients** with a **subcapital femoral neck fracture**, **cemented THR** is preferred due to: - **Better long-term function** (compared to hemiarthroplasty). - **Lower revision rates** (avoids acetabular wear from hemiarthroplasty). Other options: - **A) DHS**: Used for intertrochanteric fractures, not intracapsular fractures. - **B) Hemiarthroplasty**: Reserved for less active patients. - **D) Cannulated screws**: For non-displaced fractures in younger patients.

Answer 207

The most likely diagnosis in this case is Addison’s disease (acute adrenal insufficiency). Explanation: • The patient has a history of autoimmune conditions (rheumatoid arthritis and polymyalgia rheumatica), which increases the risk of adrenal insufficiency due to autoimmune adrenalitis. • She develops delirium and hypotension postoperatively, which are classic signs of adrenal crisis. • The blood results show: • Hyponatremia (Na+ 132 mmol/L) → Common in adrenal insufficiency due to lack of aldosterone. • Hyperkalemia (K+ 5.3 mmol/L) → Due to reduced aldosterone, leading to potassium retention. • Leukocytosis (WBC 15.4 × 10⁹/L) → Can occur due to stress and inflammation. • Normal hemoglobin and platelets → Rules out significant hemorrhage. • The stress of surgery would have increased cortisol demand, and if she was on long-term steroids (for her autoimmune conditions), abrupt cessation or insufficient perioperative steroid cover could have precipitated an adrenal crisis. Why not the other options? • Conn’s syndrome (primary hyperaldosteronism) → Would present with hypertension, hypokalemia, and metabolic alkalosis, none of which are seen here. • Phaeochromocytoma → Typically presents with paroxysmal hypertension, palpitations, and headaches, rather than postoperative hypotension and hyperkalemia. • Graves’ disease (thyrotoxicosis) → Would cause tachycardia, heat intolerance, and hyperreflexia, but not hyponatremia or hyperkalemia. Management: • Immediate IV hydrocortisone (100 mg stat, then 50 mg every 6 hours) • IV fluids (0.9% saline) to correct hypotension and electrolyte imbalance • Monitor electrolytes and blood glucose • Check cortisol levels and ACTH to confirm adrenal insufficiency Thus, the correct answer is: (a) Addison’s disease

Answer 208

The correct answer is: (c) Superficial Peroneal Nerve Explanation: The superficial peroneal nerve (a branch of the common peroneal nerve) is responsible for: • Motor function: Eversion of the foot (via fibularis longus and fibularis brevis muscles). • Sensory function: Provides sensation to most of the dorsum of the foot (except the first web space, which is supplied by the deep peroneal nerve). Why is this the most likely nerve injured? • Varicose vein surgery involves the great saphenous vein, which runs along the medial aspect of the leg. The superficial peroneal nerve, as it descends in the lateral compartment of the leg, becomes more superficial and can be injured during venous stripping or ligation procedures. • The patient’s symptoms include: • Weakness in dorsiflexion and eversion: The superficial peroneal nerve mainly affects eversion (fibularis longus/brevis), but it also contributes slightly to dorsiflexion. • Loss of sensation over the dorsum of the foot: This matches the sensory distribution of the superficial peroneal nerve. Why not the other options? • Deep peroneal nerve (a): Primarily responsible for dorsiflexion (via tibialis anterior, extensor hallucis longus, extensor digitorum longus). However, it does not significantly affect eversion and only provides sensory innervation to the first web space. • Saphenous nerve (b): Purely sensory, providing sensation to the medial aspect of the leg and foot—it does not control muscle movement. • Sural nerve (d): Purely sensory, providing sensation to the lateral foot and ankle, and does not affect dorsiflexion or eversion. Summary: The combination of weakness in eversion and dorsiflexion along with sensory loss over the dorsum of the foot strongly suggests superficial peroneal nerve injury, making (c) Superficial Peroneal Nerve the correct answer.

Answer 209

The correct answer is: (b) CEA (Carcinoembryonic Antigen) Explanation: • Medullary Thyroid Cancer (MTC) arises from the parafollicular C-cells of the thyroid, which produce calcitonin. • Calcitonin is the most important tumor marker for monitoring recurrence, but since it is not an option, we consider CEA (Carcinoembryonic Antigen). • CEA is a secondary tumor marker that can be elevated in advanced or recurrent MTC, making it useful for follow-up. Why not the other options? • Thyroglobulin (a) → Used to monitor papillary and follicular thyroid cancers, but not MTC (as MTC arises from C-cells, which do not produce thyroglobulin). • TSH (c) → Not relevant for MTC follow-up, as MTC is not dependent on TSH stimulation. • TRH (d) → Not used in MTC follow-up; its role is in regulating TSH secretion. • T4 (e) → Thyroid hormone levels are monitored after thyroidectomy, but they are not used for MTC-specific follow-up. Summary: Since calcitonin is not an option, the best available choice for MTC follow-up is CEA (Carcinoembryonic Antigen), making (b) CEA the correct answer.

Answer 210

The most specific factor for rheumatoid arthritis (RA) among the given options is none of them directly—however, among commonly tested and clinically relevant antibodies for RA, the anti-cyclic citrullinated peptide antibody (anti-CCP) is the most specific. Among the options listed: • A. ANCA – Associated with vasculitis (e.g., granulomatosis with polyangiitis), not RA. • B. ANA – Common in systemic lupus erythematosus, not specific for RA. • C. Antimitochondrial antibody – Seen in primary biliary cholangitis. • D. Antiphospholipid antibodies – Related to antiphospholipid syndrome. So, while these antibodies are associated with various autoimmune diseases, none are specific for RA. The best answer for RA, based on typical MRCS options (even if not listed here), is anti-CCP for specificity, and rheumatoid factor (RF) for sensitivity. Between the four given options—ANCA, ANA, Antimitochondrial antibody, and Antiphospholipid antibodies—the least incorrect or relatively more relevant one for rheumatoid arthritis would be: B. ANA (Antinuclear Antibody) While ANA is not specific to RA (and more commonly associated with SLE), it can be positive in some RA patients, especially in overlap syndromes. It’s not diagnostic or highly specific, but among the four, it’s the most likely to appear in someone with RA. So if you’re forced to choose from these four only, B. ANA is the best available option. However, keep in mind for exams: anti-CCP is the most specific for RA.

Answer 211

Given the clinical scenario: • Tall pregnant woman (tall stature suggests possible Marfan syndrome, which is a risk factor for aortic pathology) • 36 weeks gestation (increased cardiovascular demand and hypercoagulability) • Sudden sharp chest pain • Family history of MI (suggests cardiovascular risk) Best analysis: • Aortic dissection is classically associated with Marfan syndrome, tall stature, pregnancy (especially late third trimester), and sudden sharp “tearing” chest or back pain. • Pulmonary embolism is also a risk in pregnancy but typically presents with pleuritic pain, dyspnea, and sometimes tachycardia/hypoxia. • Myocardial infarction is less common at this age without other strong risk factors. • Pericarditis causes positional chest pain, typically worse lying down and relieved by leaning forward. Most likely diagnosis: A. Aortic dissection This is the best fit considering the tall stature, pregnancy, and sudden onset of sharp chest pain. The mortality risk and urgency make it the top differential.

Answer 212

In a tracheostomy, particularly a surgical one, the following structures are at risk of injury: • Anterior jugular vein – lies in the midline and may cross the surgical field. • Thyroid isthmus – often overlies the second and third tracheal rings. • Recurrent laryngeal nerve – located posterolaterally to the trachea; risk increases in lower tracheostomies. • Platysma – superficial muscle, always cut during open tracheostomy. Now, let’s consider: A. Ascending pharyngeal artery – This artery is a branch of the external carotid artery, running deep in the pharyngeal region, far posterior and lateral to the typical tracheostomy site. Correct answer: A. Ascending pharyngeal artery – Least likely to be injured during a tracheostomy due to its deep and posterior location.

Answer 213

The main support of the cervix (and uterus in general) is provided by the cardinal ligaments, also known as: D. Transverse cervical ligament These ligaments extend from the lateral pelvic wall to the cervix and upper vagina, providing horizontal support and preventing prolapse. They carry important vessels like the uterine artery. Quick notes on the other options: • A. Broad ligament: a peritoneal fold that holds the uterus but offers little structural support. • B. Ovarian ligament: connects ovary to uterus, not involved in cervix support. • C. Round ligament: helps maintain anteversion of the uterus, not cervix support. Correct answer: D. Transverse cervical ligament

Answer 214

Great question! You’re being asked to pick out a physiological sign of anxiety, which triggers a sympathetic (fight-or-flight) response. Let’s analyze the options: • A. Bronchodilation – YES: This is a classic sympathetic response to anxiety or stress. • B. Micturition – NO: Urination is typically associated with parasympathetic activation. • C. Miosis – NO: Pupil constriction is parasympathetic; anxiety causes mydriasis (dilation). • D. Increased peristalsis – NO: GI activity is reduced during sympathetic activation. Correct answer: A. Bronchodilation This helps increase airflow during a fight-or-flight state like preoperative anxiety.

Answer 215

Dry gangrene of the toe: • This is non-infected, dry, and well-demarcated tissue death due to ischemia. • In such cases, revascularization is still indicated before any major amputation or surgical removal of the gangrenous area, especially if there’s potential for limb salvage—as in this patient who has a patent posterior tibial artery. Why revascularization first? • Because if you amputate without restoring blood flow, healing is impaired or impossible, and infection risk increases. • After revascularization, the gangrenous part can dry out further or auto-amputate, or you can plan a minor amputation (e.g. toe) in a well-perfused field. So, despite the presence of gangrene, the standard vascular surgery approach is: 1. Assess viability and potential for limb salvage 2. Revascularize if possible 3. Then do limited amputation if needed Thus, the answer remains: C. Femoro-posterior tibial bypass graft

Answer 216

In a child with cleft palate, recurrent ear infections (otitis media with effusion) are common due to dysfunction of the Eustachian tube. This is because the muscle responsible for opening the Eustachian tube during swallowing is often dysfunctional or malformed. The key muscle involved is: C. Levator palati muscle (also known as levator veli palatini) • This muscle, along with tensor veli palatini, helps elevate the soft palate and opens the pharyngotympanic (Eustachian) tube. • In cleft palate, these muscles are often malpositioned or hypoplastic, leading to poor drainage from the middle ear and recurrent infections. Other options: • Medial pterygoid – jaw movement, not involved in Eustachian tube function. • Stapedius – controls stapes bone in the middle ear, not related to infections. • Orbicularis oris – around the mouth, involved in lip movement. • Pharyngeal constrictors – help with swallowing, not directly involved in Eustachian tube function. Correct answer: C. Levator palati muscle

Answer 217

In the context of low tissue perfusion, the test that becomes unreliable is: E. Pulse oximetry Why? • Pulse oximeters rely on detecting pulsatile blood flow to measure oxygen saturation (SpO2). • In states of low perfusion (e.g. shock, hypothermia, severe vasoconstriction), the signal is weak or inaccurate, leading to false low or unreadable readings. • It can also be affected by factors like motion, nail polish, or carbon monoxide poisoning. Let’s quickly rule out the others: • A. FEV1 and D. PEF – spirometric values, unrelated to perfusion. • B. PCO2 and C. PO2 – measured in arterial blood gases (ABGs), which are direct and reliable even in low perfusion (assuming arterial sampling is successful). Correct answer: E. Pulse oximetry

Answer 218

The pterion is a critical anatomical landmark on the lateral side of the skull where four bones meet: 1. **Frontal bone** 2. **Parietal bone** 3. **Greater wing of the sphenoid bone** 4. **Squamous part of the temporal bone** In this case, the **temporal bone's contribution to the pterion** is its **squamous part** (a flat, thin portion), not the petrous, mastoid, or tympanic parts. ### Why not the other options? - **A. Petrous**: The dense, pyramid-shaped part housing the inner ear (not part of the pterion). - **C. Lesser wing of sphenoid**: Located more posteriorly and superiorly, not part of the pterion. - **D. Mastoid**: The bony prominence behind the ear, not involved in the pterion. - **E. Tympanic**: Forms part of the external auditory canal, not part of the pterion. ### Key Point: The **squamous part of the temporal bone** is the correct answer because it forms part of the pterion, which is a common site for **extradural (epidural) hemorrhage** due to injury to the **middle meningeal artery** running deep to it. **Answer: B. Squamous**

Answer 219

The **thoracic duct** is the largest lymphatic vessel in the body, draining most of the body's lymph into the venous system. When injured (e.g., during thoracic surgery), it is typically ligated to prevent **chylothorax** (lymphatic fluid leakage into the pleural cavity). ### **Where is the thoracic duct most likely injured?** The **thoracic duct** ascends through the **posterior mediastinum** and crosses from the **right to the left side** at the level of **T4-T5** (near the **aortic arch**). It then empties into the **venous system at the junction of the left subclavian vein and left internal jugular vein**. ### **Key Anatomical Landmarks for the Thoracic Duct:** 1. **Posterior mediastinum** (between **aortic hiatus (T12)** and **aortic arch (T4-T5)**) 2. **Crosses midline at T4-T5** 3. **Terminates at the venous angle (junction of left subclavian & internal jugular veins)** ### **Why is the correct answer E?** - The **most common site of iatrogenic injury** is near its **terminal portion**, where it joins the **left subclavian vein** (during neck or thoracic surgery). - Ligation is usually performed **low in the chest** (posterior mediastinum) to avoid recurrence of chylothorax. ### **Why not the other options?** - **A. Behind ascending aorta** → The thoracic duct runs behind the **esophagus**, not the ascending aorta. - **B. Venacaval opening** → The **azygos vein** passes through here, not the thoracic duct. - **C. Esophageal opening** → The thoracic duct runs **posterior to the esophagus**, but injury here is less common than near its termination. - **D. Aortic hiatus (T12)** → The thoracic duct **enters the abdomen here**, but surgical injury is more likely higher up. ### **Final Answer:** **E. At junction with the subclavian vein** (most common site of injury and ligation).

Answer 220

The most likely diagnosis in this case is **A. Acute Intermittent Porphyria (AIP)**. ### **Key Findings Supporting AIP:** 1. **Clinical Presentation:** - **Acute abdominal pain + vomiting + muscle weakness** (classic triad of AIP). - **Hypertension (160/85 mmHg)** and **tachycardia (86 bpm)** due to autonomic dysfunction. - **Recent combined oral contraceptive (COC) pill use** (a known trigger for AIP). 2. **Lab Findings:** - **Mildly elevated ALT & ALP** (liver involvement due to porphyrin accumulation). - **Hyponatremia** (not given but common in AIP due to SIADH). - **Normal amylase** (rules out pancreatitis). - **Normal calcium & glucose** (rules out hypoparathyroidism and DKA). - **Elevated triglycerides** (can occur in AIP due to metabolic dysregulation). 3. **Why Not Other Options?** - **B. Diabetic Ketoacidosis (DKA):** No hyperglycemia, ketonuria, or acidosis. - **C. Hypoparathyroidism:** Normal calcium, no neuromuscular irritability (e.g., Chvostek/Trousseau signs). - **D. Mumps:** No parotitis, normal amylase (mumps pancreatitis would raise amylase). - **E. Pancreatitis:** Normal amylase/lipase, no imaging findings (though mild ALT/ALP elevation can occur in biliary pancreatitis, the clinical picture fits AIP better). ### **Diagnostic Confirmation:** - **Urine porphobilinogen (PBG) & delta-ALA** (markedly elevated during attacks). - **Urine may turn dark (red-brown) on standing** due to porphyrin oxidation. ### **Management:** - **Immediate: IV heme arginate (Panhematin) + high-dose glucose.** - **Avoid triggers (COC pills, fasting, certain drugs).** ### **Final Answer: A. Acute Intermittent Porphyria (AIP)**

Answer 221

The correct answer is: ### **C. Erector spinae muscle** #### **Why?** - The **erector spinae** is the primary **postural muscle** that supports the **vertebral column** and helps maintain an upright posture. - In **disc prolapse (herniation)**, strengthening the **erector spinae** helps **stabilize the spine**, reduce mechanical stress on the intervertebral discs, and prevent further injury. - Physiotherapy often focuses on **core stabilization**, and the erector spinae is a key muscle in this process. #### **Why Not the Others?** - **A. Quadratus lumborum** – Primarily involved in lateral flexion and hip hiking, not the main target for disc prolapse rehab. - **B. Transversus abdominis** – Important for core stability but more of a deep stabilizer rather than the primary muscle targeted in back physiotherapy. - **D. External oblique muscle** – Mainly involved in trunk rotation and flexion, not the primary muscle for spinal extension/stabilization. - **E. Latissimus dorsi** – A large upper body muscle involved in shoulder movement, not directly related to spinal support in disc prolapse. #### **Key Takeaway:** For **disc prolapse rehabilitation**, the **erector spinae** is the **primary muscle strengthened** to improve spinal support and reduce strain on the intervertebral discs. **Answer: C. Erector spinae muscle**

Answer 222

During adrenal (suprarenal) surgery, understanding the anatomical relationships is crucial. The left suprarenal gland lies in the left upper quadrant, and the lower pole of the gland lies medially near specific structures. Let’s go through the options and the relevant anatomy: ⸻ Anatomical relations of the left adrenal gland: • Superiorly: Diaphragm • Inferiorly: Left kidney • Medially (lower pole): Left renal vein — this vein crosses anterior to the aorta, just below the adrenal gland, and typically drains the left adrenal vein. • Anteriorly: Pancreas and splenic vessels (but not as closely related to the lower pole medially) • Posteriorly: Left crus of the diaphragm ⸻ Evaluation of Options: • a. Celiac ganglion — too high and more anterior • b. Left renal vein — correct; this vein runs medial and just below the left adrenal gland, and the left adrenal vein drains directly into it • c. Left crus of diaphragm — more posterior and medial, not typically in direct contact with the lower pole • d. Body of pancreas — anterior to the gland, not directly related to the lower pole • e. Splenic artery — runs along the superior border of the pancreas, so it’s more anterior and superior ⸻ **Correct answer: b. Left renal vein ⸻ Reference: • Gray’s Anatomy: The Anatomical Basis of Clinical Practice • Moore’s Clinically Oriented Anatomy

Answer 223

The splenic artery supplies the spleen, but it also has branches that affect other structures in the abdominal cavity. Specifically, the splenic artery gives rise to branches that supply the fundus of the stomach, pancreas, and parts of the colon. Let’s review the structures supplied by the splenic artery and its branches: 1. Fundus of stomach – The short gastric arteries, which are branches of the splenic artery, supply the fundus of the stomach. 2. Head of pancreas – The splenic artery mainly supplies the body and tail of the pancreas, while the head is primarily supplied by the pancreaticoduodenal arteries, which arise from the common hepatic artery (not the splenic artery). 3. Colon – The left colic artery, a branch of the splenic artery, supplies part of the colon, specifically the descending colon and the sigmoid colon. 4. Duodenum – The duodenum is mainly supplied by the pancreaticoduodenal arteries (from the common hepatic artery), not by the splenic artery. 5. Small bowel – The small bowel is primarily supplied by the superior mesenteric artery, not the splenic artery. ⸻ Correct answer: a. Fundus of stomach ⸻ The fundus of the stomach is most directly affected by an aneurysm of the splenic artery due to the presence of the short gastric arteries.

Answer 224

When a 14-year-old child presents with left knee pain and a normal knee X-ray, it is important to consider the possibility that the pain may be referred from another joint or structure, particularly from the hip or pelvis, since referred pain can sometimes present as knee pain. Given the situation, the next step should be to evaluate the possibility of hip pathology, as conditions like Slipped Capital Femoral Epiphysis (SCFE) or hip joint issues can present as knee pain in children. Evaluating the options: • a. X-ray left Hip AP — This is a reasonable first step because hip pathology can cause referred pain to the knee. An AP (anteroposterior) view of the hip would help identify any structural issues in the hip joint, such as SCFE or other conditions that may present with knee pain. • b. X-ray pelvis AP and lateral — A more comprehensive approach, but may be less targeted than the hip X-ray specifically. It could be useful for broader screening of any pelvis-related issues. • c. MRI — While MRI is more sensitive than X-ray for soft tissue and bone abnormalities, it’s typically not the first step unless there’s a high clinical suspicion for a soft tissue injury or internal joint issues that aren’t visible on X-ray. • d. CT — Generally, CT is used for more detailed imaging, but it’s not typically the first-line imaging for knee or hip issues in children unless there’s concern for complex fractures or bone deformities that X-ray cannot adequately assess. • e. X-ray frog view — This is a specific view used to assess the hip joint, particularly for issues like SCFE or hip dislocations. However, it may not be the first imaging step compared to the standard hip AP view. ⸻ Correct answer: a. X-ray left Hip AP This will help rule out any issues with the hip, which could be causing referred pain to the knee. If the hip X-ray is normal and the symptoms persist, further imaging (like MRI) might be considered based on the clinical examination.

Answer 225

In complete obstruction of the common bile duct, the following events typically occur due to the blockage of bile flow: 1. Increased direct serum bilirubin — This occurs because conjugated bilirubin (direct bilirubin) cannot be excreted into the bile and backs up into the bloodstream. 2. Increased serum alkaline phosphatase — This enzyme is released from the liver and bile ducts when there is obstruction, so it becomes elevated in cases of bile duct obstruction. 3. Presence of bilirubin in the urine — When conjugated (direct) bilirubin backs up into the bloodstream, it can be filtered by the kidneys and appear in the urine. 4. Increased indirect serum bilirubin — Indirect bilirubin is unconjugated bilirubin, which is not typically increased in complete bile duct obstruction. Instead, the increase is primarily in direct bilirubin because the liver is still processing bilirubin but cannot excrete it into the bile due to the obstruction. The exception is: ⸻ Correct answer: b. Increased indirect serum bilirubin In complete obstruction of the common bile duct, the primary bilirubin abnormality is an increase in direct bilirubin, not indirect bilirubin.

Answer 226

The correct answer is: ### **A. Dopamine** #### **Explanation:** Dopamine is a **precursor of norepinephrine (noradrenaline) and epinephrine (adrenaline)**. Its effects are **dose-dependent**: 1. **Low dose (0.5–2 mcg/kg/min):** - Stimulates **dopamine D1 receptors** (renal and mesenteric vasodilation). - Also has **minor β1-adrenergic effects** (increases heart rate and contractility). 2. **Intermediate dose (2–10 mcg/kg/min):** - **Predominantly stimulates β1 receptors** (increases cardiac output via inotropy and chronotropy). 3. **High dose (>10 mcg/kg/min):** - Stimulates **α1-adrenergic receptors** (vasoconstriction, increased blood pressure). #### **Why Not the Others?** - **B. Dobutamine** – Pure **β1 agonist** (no α1 effects at any dose). - **C. Noradrenaline (Norepinephrine)** – Primarily **α1 and β1 agonist**, but not a precursor. - **D. Adrenaline (Epinephrine)** – Stimulates **β1 (heart), β2 (lungs), and α1 (vasoconstriction)**, but not a precursor. - **E. Serotonin** – Acts on **5-HT receptors**, not adrenergic receptors. #### **Key Point:** Dopamine is unique because it is **metabolized into norepinephrine** and exhibits **dose-dependent receptor stimulation** (D1/β1 at low doses, α1 at high doses). **Answer: A. Dopamine**

Answer 227

Given the patient’s history of a recent injury from pruning rose bushes and the clinical presentation of a raised ulcerated lesion that bleeds easily on contact, the most likely diagnosis is pyogenic granuloma. Here’s a breakdown of the options: A. Pyogenic granuloma • Commonly associated with trauma (such as pruning or injury, as in this case). • Appearance: A raised, ulcerated lesion that can bleed easily. It is a type of benign vascular lesion that can occur rapidly following trauma or irritation. • Correct answer: A. Pyogenic granuloma B. Keratoacanthoma • This lesion is a well-defined, rapidly growing nodule with a central keratin plug. It is often found on sun-exposed areas, not typically after trauma from something like pruning bushes. C. Dermatofibroma • Dermatofibromas are benign fibrous skin growths that are usually firm, brownish, and not ulcerated. They do not bleed easily on contact. D. Basal cell carcinoma • Basal cell carcinoma usually presents as a painless, slowly growing ulcer or a pearly nodule on sun-exposed areas, often with telangiectasia. It is unlikely to present so acutely with easy bleeding after trauma. E. Epidermoid cyst • Epidermoid cysts are typically firm, mobile lumps under the skin, often with a central punctum. They are not usually associated with ulceration and bleeding after trauma. ⸻ Correct answer: A. Pyogenic granuloma

Answer 228

The correct answer is: B. It contains macrophages. Explanation: Let’s evaluate each option: • A. It characteristically shows haemorrhagic rather than ischaemic infarcts. Incorrect. The spleen typically shows wedge-shaped pale (ischaemic) infarcts due to its end-artery blood supply. Haemorrhagic infarcts are more common in organs with dual blood supply like the lungs. • B. It contains macrophages. Correct. The spleen contains many macrophages, particularly in the red pulp, where they are responsible for the phagocytosis of aged red blood cells and pathogens. • C. It contains medullary sinuses. Incorrect. Medullary sinuses are found in lymph nodes, not the spleen. • D. It is a primary lymphoid organ in the immune system. Incorrect. The spleen is a secondary lymphoid organ, involved in immune surveillance and response, not in the production of lymphocytes (which occurs in primary organs like bone marrow and thymus). • E. It is a site of hematopoiesis in the normal adult. Incorrect. Hematopoiesis in adults primarily occurs in the bone marrow. The spleen only resumes this function in cases of extramedullary hematopoiesis (e.g., in myelofibrosis).

Answer 229

The **most likely cause** of this patient's **low urine output** is: ### **C. Hypovolemic shock** #### **Key Points Supporting the Diagnosis:** 1. **Mechanism of injury** – Major trauma (femoral + pelvic fractures) → **significant blood loss** (femur fracture can lose **1–1.5 L**, pelvic fracture **up to 3 L**). 2. **Initial catheter output (250 mL)** – Likely residual bladder volume, followed by **oliguria (<10 mL/hr)** due to **hypovolemia**. 3. **Clinical context** – Trauma-induced **hemorrhagic shock** is the **most common cause of oliguria** in this scenario. #### **Why Not the Others?** - **A. Blocked catheter** – Possible, but **less likely** without other signs (e.g., painful bladder, abdominal distension). A quick flush/check would rule this out. - **B. Cardiogenic shock** – Unlikely in a young trauma patient unless pre-existing cardiac disease (no signs of heart failure). - **D. Ruptured bladder** – Possible with pelvic fracture, but **classic findings** include **gross hematuria, suprapubic pain, inability to void** (not just oliguria). - **E. Septic shock** – Too early post-trauma (would require time for infection to develop). #### **Next Steps:** - **Aggressive IV fluid resuscitation** + **blood transfusion** (if Hb low). - **Reassess for ongoing bleeding** (pelvic binder? FAST scan?). - **Monitor urine output** after volume replacement (should improve if hypovolemia is the cause).

Answer 230

The correct answer is: C. Sodium concentration of 10 mmol/L Explanation: This patient is hypovolemic following intraoperative bleeding, which has resulted in pre-renal acute kidney injury. In this state, the kidneys attempt to conserve sodium and water to maintain intravascular volume. Here’s what we expect in pre-renal failure: • Low urine sodium (<20 mmol/L) – typically around 10 mmol/L – due to active reabsorption. • High urine osmolarity (>500 mOsm/kg) – concentrated urine due to ADH release. • High urine specific gravity (>1.020) – another indicator of concentrated urine. • Urine/plasma osmolarity ratio >1.5:1 – shows effective concentrating ability of the kidney. • No nitrites unless there’s infection – which is not indicated here. Let’s look at each option: • A. Osmolarity of 250 mOsm/kg/H2O – Too dilute; expected in acute tubular necrosis (intrinsic renal failure), not pre-renal. • B. Presence of nitrites – Suggests infection, which is not relevant here. • C. Sodium concentration of 10 mmol/L – Correct. Consistent with hypovolemia and intact renal response. • D. Specific gravity of 1010 – Isosthenuria; seen in intrinsic renal failure when kidneys can’t concentrate. • E. Urine/plasma osmolarity of 1:1 – Also suggests renal failure, not pre-renal causes.

Answer 231

The question describes a superior orbital fissure syndrome, which is typically due to trauma or compression affecting the contents of the fissure. These include cranial nerves III (oculomotor), IV (trochlear), V1 (ophthalmic branch of trigeminal), and VI (abducens), as well as the superior ophthalmic vein. Here’s a breakdown of the symptoms and signs mentioned and associated deficits: • Ipsilateral pupillary defect: implies damage to cranial nerve III (parasympathetic fibers to the pupil). • Loss of corneal reflex: V1 (sensory limb via the nasociliary branch). • Complete ophthalmoplegia: paralysis of all extraocular muscles (III, IV, VI). • Ptosis: due to paralysis of the levator palpebrae superioris (cranial nerve III). • Enophthalmos: may occur due to loss of orbital contents support or sympathetic paralysis. Now, evaluating the options: • Altered cutaneous sensation from the forehead to the vertex: involves the ophthalmic nerve (V1), which does go through the superior orbital fissure. • Ptosis: via CN III – present. • Complete ophthalmoplegia: CN III, IV, VI involvement – present. • Nystagmus: not typically a feature of superior orbital fissure syndrome – this relates more to vestibular dysfunction or cerebellar causes. • Enophthalmos: may be seen if the sympathetic fibers or structural support is affected – can be present. Correct Answer: Nystagmus This is not typically seen with superior orbital fissure syndrome.

Answer 232

In the scenario described—acute severe knee pain with inability to move the leg, and no signs of systemic infection (apyrexial, normal WBC)—the concern is to distinguish between possible causes like: • Crystal arthropathy (e.g., gout, pseudogout) • Septic arthritis (still a possibility even if afebrile) • Hemarthrosis • Other intra-articular pathology (e.g., meniscal tear) Knee aspiration is the most definitive investigation, as it allows: • Direct visualization of the synovial fluid (color, turbidity) • Microscopy for crystals (urate, calcium pyrophosphate) • Culture and Gram stain (to rule out infection) Other options: • X-ray: useful for bony abnormalities but not definitive for soft tissue or early joint pathology. • ESR: nonspecific marker of inflammation. • Ultrasound: can detect effusion but cannot define the etiology. • Arthroscopy: invasive and not first-line for diagnostic purposes. Correct Answer: Knee aspiration

Answer 233

The correct answer is: Use in tissues which are infected Explanation: Lignocaine (lidocaine) is a local anesthetic that works by blocking sodium channels and preventing nerve impulse transmission. Several factors can affect its efficacy: Let’s break down the options: • Hyperkalemia: This affects resting membrane potential, but not significantly the efficacy of lignocaine directly. • Administration with adrenaline: Enhances and prolongs the effect by causing vasoconstriction, slowing lignocaine absorption. • Administration with bupivacaine: This can be done for mixed-duration anesthesia, but doesn’t attenuate lignocaine’s action. • Administration with sodium bicarbonate: This enhances lignocaine’s onset by increasing pH, making more of the drug non-ionized and active. • Use in infected tissue: Correct answer. Infected tissues are acidic, which increases ionization of lignocaine, reducing its ability to cross nerve membranes and diminishing its effectiveness. Infected (acidic) environments = reduced efficacy of lignocaine.

Answer 234

The middle cerebral artery (MCA) supplies a large portion of the lateral cerebral hemisphere, including the motor and sensory cortex for the face and upper limb, as well as Broca’s and Wernicke’s areas in the dominant hemisphere. Likely findings in an MCA stroke include: • Contralateral hemiplegia, with upper limb and face more affected than lower limb. • Contralateral sensory loss in the same distribution. • Contralateral lower face weakness (with forehead sparing, since the upper face gets bilateral innervation). • Possible aphasia (if dominant hemisphere is affected). • Visual field defects like homonymous hemianopia. Best Answer: Contralateral hemiplegia affecting upper limb more than lower limb

Answer 235

The best method to assess whether different methods of perioperative shaving affect postoperative wound infection rates is: Randomised controlled study Explanation: • An RCT (Randomised Controlled Trial) is the gold standard for comparing interventions, like methods of shaving. • It minimizes bias by randomly allocating participants into different groups, ensuring that confounding variables are equally distributed. • This allows for causal inferences about the effect of each shaving method on infection rates. Why not the others? • Cohort study: Observational and less control over variables. • Retrospective study: Prone to bias, as it looks back at existing records. • Case-controlled study: Good for rare outcomes but not ideal for comparing interventions. • Cross-over study: Less suitable here since wound infections are one-time events after surgery—not reversible or repeatable in the same subject. Correct Answer: Randomised controlled study

Answer 236

In a 2-year-old boy with one non-palpable testis and the other normal, the most appropriate initial management is to determine whether the non-palpable testis is undescended, absent, or intra-abdominal. Let’s evaluate the options: • A. Ultrasound (U/S): Not useful — low sensitivity for locating non-palpable testes, especially intra-abdominal ones. • B. HCG stimulation: Outdated and not recommended for localization or treatment. • C. Laparoscopy: Excellent for diagnosis and possible treatment if the testis is intra-abdominal, but it’s not the first step unless the testis is non-palpable after examination under anesthesia. • D. Inguinal exploration: Correct Answer — this is the first step if there is suspicion that the testis may be in the inguinal canal but not palpable. • E. E.CT (likely meant CT scan): Not used for this purpose due to radiation and poor diagnostic value. Correct Answer: D. Inguinal exploration This allows the surgeon to both diagnose and potentially correct the undescended testis if found in the inguinal region.

Answer 237

The patient has acute calcium pyrophosphate deposition disease (CPPD), commonly known as pseudogout, confirmed by the identification of calcium pyrophosphate crystals in synovial fluid. Important associations: CPPD is often secondary to metabolic conditions, and it’s crucial to screen for underlying causes. Key associations include: • Hyperparathyroidism • Hemochromatosis • Hypomagnesemia • Hypophosphatasia Among the options, the most useful test is: Transferrin saturation Why? This helps screen for hemochromatosis, a common metabolic cause of CPPD, especially in middle-aged individuals. Hemochromatosis leads to iron overload, and transferrin saturation is a sensitive early marker. Briefly on the others: • ACTH: Relevant to adrenal axis, not linked to CPPD. • ANA: Screens for autoimmune disease (e.g., lupus), not typically related to CPPD. • Serum ferritin: May be elevated in inflammation; less specific for iron overload than transferrin saturation. • LDH: Marker of tissue breakdown; nonspecific. Correct Answer: Transferrin saturation

Answer 238

The correct answer is: C. Lymphoma Explanation: This case presents key clues pointing toward thyroid lymphoma: • Age and gender: 45-year-old woman – thyroid lymphoma is more common in middle-aged to older women. • Normal thyroid profile: Often seen in lymphomas, which may not initially disrupt thyroid hormone production. • CD20 cells: These are B lymphocytes and a hallmark of B-cell lymphomas. • Empty pale nuclei: This description can be associated with lymphocytic infiltration, but is not classic for papillary carcinoma. • Atypical lymphocytic cells: Strongly suggest lymphoma, especially when associated with CD20 positivity. Now let’s evaluate the other options: • A. Papillary thyroid carcinoma: Characterized by Orphan Annie eye nuclei, nuclear grooves, and psammoma bodies – not CD20+ cells. • B. Hashimoto thyroiditis: Shows lymphocytic infiltration, but with plasma cells, Hurthle cells, and typically a background of hypothyroidism. It is also associated with CD3 (T-cell), not CD20. • D. Follicular thyroid carcinoma: Characterized by capsular and vascular invasion, and follicular architecture, not lymphoid cells. • E. None of the above: Not applicable as lymphoma fits best.

Answer 239

The **most likely answer** is: ### **C. Collecting duct** #### **Explanation:** The patient developed **cerebral edema** followed by **polyuria (350 mL/hour)**, which strongly suggests **central diabetes insipidus (DI)** due to **disruption of antidiuretic hormone (ADH) secretion or action**. - **ADH (vasopressin)** acts primarily on the **collecting ducts** of the kidney to promote water reabsorption. - **Damage to the hypothalamus/pituitary** (e.g., from trauma or cerebral edema) → **ADH deficiency** → **failure to concentrate urine** → **massive dilute urine output**. #### **Why Not the Others?** - **A. Proximal convoluted tubule (PCT)** – Damage here causes **Fanconi syndrome** (bicarb, glucose, phosphate wasting), not isolated polyuria. - **B. Distal convoluted tubule (DCT)** – Affects sodium/chloride regulation (e.g., Bartter/Gitelman syndromes), not pure water loss. - **D. Thick ascending limb (TAL)** – Loop diuretics act here, causing **isosthenuric urine**, but not this extreme polyuria. - **E. Adrenal medulla** – Secretes catecholamines, not involved in water balance. #### **Diagnosis & Management:** - **Water deprivation test + desmopressin trial** to confirm central DI. - **Desmopressin (ADH analog)** will correct the polyuria if the issue is ADH deficiency.

Answer 240

The correct answer is: E. Stenosis of the subclavian artery proximal to the first branch Explanation: This patient likely has subclavian steal syndrome, especially given: • Use of the internal thoracic (mammary) arteries for bypass grafting. • Symptoms of angina induced by arm exertion (e.g., hanging clothes) – which increases demand in the affected arm. • History of heavy smoking, a major risk factor for atherosclerosis. Key Anatomy & Physiology: • The internal thoracic artery arises from the subclavian artery. • In subclavian steal syndrome, proximal subclavian artery stenosis (before the origin of the vertebral and internal thoracic arteries) causes blood to flow in reverse from the vertebral artery or internal thoracic artery to supply the arm – “stealing” blood from the coronary or cerebral circulation. • This results in myocardial ischemia or neurological symptoms during arm activity. Let’s rule out the other options: • A & B (micro-emboli): Would cause neurological signs (e.g., stroke, TIA), not isolated angina with arm exertion. • C & D (distal stenosis): Would not cause a steal phenomenon from the internal thoracic artery, as they are downstream of the artery’s origin. Clinical Pearl: Always consider subclavian steal syndrome when there’s exertion-induced ischemia in the context of arterial grafting from the internal thoracic artery and proximal subclavian stenosis.

Answer 241

The correct answer is: E. Unopposed sympathetic innervation of dilator pupillae Explanation: This patient has a left-sided fixed dilated pupil in the context of a left-sided extradural (epidural) hematoma and a very low GCS (5). This is a neurosurgical emergency, and the most likely physiological mechanism is compression of the oculomotor nerve (cranial nerve III). How does this lead to a dilated pupil? • The oculomotor nerve (CN III) carries parasympathetic fibers that innervate the sphincter pupillae, which constricts the pupil. • Compression of this nerve (often against the tentorial edge) by the expanding hematoma disrupts these parasympathetic fibers. • This results in unopposed sympathetic stimulation, which acts on the dilator pupillae muscle. • The outcome is a fixed dilated pupil (also known as a “blown pupil”) on the side of the lesion — a classic sign of transtentorial herniation. Why the other options are incorrect: • A. Increased adrenergic activity in ciliary ganglion – Incorrect; the ciliary ganglion is parasympathetic, not adrenergic. • B. Increased cholinergic activity in ciliary ganglion – Would cause constriction, not dilation. • C. Increased parasympathetic innervation of dilator pupillae – Incorrect; parasympathetic affects sphincter pupillae, not dilator. • D. Unopposed parasympathetic innervation of dilator pupillae – Incorrect terminology; parasympathetic doesn’t innervate the dilator pupillae. Summary: The dilated pupil occurs due to loss of parasympathetic input from CN III, leading to unopposed sympathetic action — so E is the best answer.

Answer 242

The correct answer is: A. Columnar epithelium with goblet cells Explanation: Barrett’s esophagus is a condition in which the normal non-keratinised stratified squamous epithelium of the distal esophagus is replaced by metaplastic columnar epithelium with goblet cells, due to chronic exposure to gastric acid in gastroesophageal reflux disease (GERD). This metaplastic change is a protective response, but it significantly increases the risk of developing esophageal adenocarcinoma. Let’s review the options: • A. Columnar epithelium with goblet cells – Correct. This is the hallmark of intestinal metaplasia seen in Barrett’s esophagus. • B. Non-keratinised stratified squamous epithelium – Normal esophageal lining; replaced in Barrett’s. • C. Pseudostratified ciliated columnar epithelium – Found in respiratory tract, not esophagus. • D. Simple cuboidal epithelium – Seen in renal tubules, not relevant here. • E. Transitional epithelium – Lines the urinary tract, not the esophagus. Summary: Barrett’s esophagus = intestinal metaplasia = columnar epithelium with goblet cells

Answer 243

The correct answer is: C. Release of adrenaline (epinephrine) from the adrenal gland Explanation: This patient’s presentation—anxiety, pallor, tachycardia, and elevated blood pressure—suggests a physiological “fight or flight” response mediated by the sympathoadrenal system. In this acute stress response: • The adrenal medulla releases adrenaline (epinephrine) into the circulation, which: • Increases heart rate and cardiac output • Causes peripheral vasoconstriction (pallor and elevated BP) • Dilates pupils and bronchioles, among other effects Why not the other options? • A. High concentration of noradrenaline within the circulation – Partially true, but the main catecholamine released into blood during stress is adrenaline, not noradrenaline. • B. Release of adrenaline from sympathetic nerve endings – Incorrect. Adrenaline is not released from sympathetic nerves; they release noradrenaline. • D. Release of noradrenaline from sympathetic ganglia – Incorrect. Ganglia do not release neurotransmitters into the circulation; they synapse locally. • E. Release of noradrenaline from the adrenal gland – Partly correct, but adrenaline is the predominant hormone released during acute stress from the adrenal medulla. Summary: This is a classic adrenaline-driven stress response, so C is spot on.

Answer 244

The correct answer is: E. Resting respiratory rate 10 Explanation: Let’s evaluate this based on what’s physiologically normal and expected for a fit 25-year-old male athlete with a height of ~180 cm: • A. Vital capacity 2L – Incorrect. That’s very low. The normal vital capacity for an adult male is typically 4.5–5.5 L, and even higher in athletes. • B. Peak expiratory flow in 1 minute is 500ml – Incorrect. This sounds like a misstatement. Peak expiratory flow (PEF) is usually measured in liters per minute, and in a healthy adult male, it’s typically 450–700 L/min, not 500 ml. • C. Forced vital capacity is 4 times than in 1st second – Incorrect. The FVC (Forced Vital Capacity) and FEV1 (Forced Expiratory Volume in 1 second) ratio is normally around 80% (FEV1/FVC ≈ 0.8). FVC is not 4 times FEV1. • D. FRC 3.5 liter – Incorrect. Functional residual capacity (FRC) in healthy adult males is usually around 2.5–3 L, not 3.5 L, although it can be slightly higher in tall individuals. • E. Resting respiratory rate 10 – Correct. The normal resting respiratory rate for adults is 12–20 breaths/min, but in athletes, it’s often lower due to high cardiopulmonary efficiency — as low as 8–10 breaths/min. Summary: The only physiologically sound and realistic option for this athletic individual is E.

Answer 245

The correct answer is: E. Stylomastoid foramen Explanation: This patient has unilateral paralysis of the muscles of facial expression but: • No loss of taste from the anterior two-thirds of the tongue • No hyperacusis (which would suggest stapedius muscle involvement) These clues indicate that the facial nerve lesion is distal to the branches that supply: • Chorda tympani (for taste) • Nerve to stapedius (for hearing modulation) The facial nerve’s course includes: 1. Internal auditory meatus – enters with the vestibulocochlear nerve. 2. Facial canal in the temporal bone – includes: • Geniculate ganglion (site of sensory cell bodies) • Branches to greater petrosal nerve (lacrimation) • Nerve to stapedius • Chorda tympani (taste and salivary glands) 3. Stylomastoid foramen – exits skull to supply muscles of facial expression 4. Parotid gland – where it divides into 5 terminal branches (TZBMC) So: • A. Internal auditory meatus – Would affect all functions (motor + taste + stapedius) – ruled out. • B. Geniculate ganglion – Would affect taste, not preserved here – ruled out. • C. Middle ear – Involvement here could damage chorda tympani and nerve to stapedius – would cause hyperacusis and loss of taste – ruled out. • D. Parotid gland – The nerve is already divided here, so a lesion would affect some but not all facial muscles – unlikely to cause complete unilateral paralysis. • E. Stylomastoid foramen – Correct. A lesion here affects only motor branches, sparing taste and hearing — matching this clinical scenario. Summary: The injury is most likely at the stylomastoid foramen, where the facial nerve exits the skull to innervate the muscles of facial expression — E is correct.

Answer 246

The correct answer is: A. Echinococcus granulosus Explanation: This patient is a sheep farmer with multiple liver cysts—a classic scenario for hydatid disease, which is caused by the parasite Echinococcus granulosus. • Echinococcus granulosus is a tapeworm whose life cycle involves: • Dogs as definitive hosts (harboring adult worms) • Sheep as intermediate hosts • Humans as accidental intermediate hosts through ingestion of eggs shed in dog feces • Hydatid cysts typically form in the liver (75%) and lungs, and may be single or multiple. • The cysts are slow-growing and can become large, causing abdominal swelling and pain. • Rupture of a cyst can cause anaphylaxis or secondary seeding. Why the others are incorrect: • B. Entamoeba histolytica – Causes amoebic liver abscess, usually solitary and often associated with fever and systemic illness, not cystic disease. • C. Enterobius vermicularis – Pinworm, affects intestines, not liver. • D. Fasciola hepatica – Liver fluke, associated with sheep, but causes biliary inflammation and fibrosis, not cyst formation. • E. Schistosoma haematobium – Affects the urinary tract, not liver. Summary: A farmer exposed to sheep and dogs with multiple liver cysts = hydatid disease = Echinococcus granulosus.

Answer 247

The correct answer is: B. Left atrium Explanation: In fetal circulation, oxygenated blood from the placenta returns to the fetus via the umbilical vein, which then flows through the ductus venosus into the inferior vena cava (IVC). From the IVC, this relatively oxygen-rich blood enters the right atrium. In the fetus, there’s a specialized structure called the foramen ovale, an opening between the right atrium and left atrium, that allows this oxygenated blood to bypass the non-functioning fetal lungs. So in an 8-month-old fetus, the majority of the blood from the IVC passes directly from the right atrium into the left atrium via the foramen ovale. Option breakdown: • A. Aorta – This is downstream; blood reaches here after passing through the left heart. • B. Left atrium – Correct. Via the foramen ovale. • C. Left ventricle – Follows the left atrium, but not immediately from the IVC. • D. Pulmonary artery – Receives blood from the right ventricle, not from IVC directly. • E. Right ventricle – Some blood does go here, but not the majority from the IVC, especially oxygenated blood. Summary: In fetal circulation, oxygenated blood from the IVC is shunted via the foramen ovale to the left atrium — hence B is the correct answer.

Answer 248

The correct answer is: E. It is related to the diaphragm Explanation: Let’s look at the anatomy and orientation of the right ventricle (RV): • The right ventricle lies anteriorly in the chest and makes up most of the anterior surface (sternocostal surface) of the heart. • It rests on the diaphragm, specifically over the central tendon – so it is indeed related to the diaphragm. • This anatomical relation becomes clinically important in pericardial effusion or pericardiocentesis. Let’s eliminate the other options: • A. It forms the apex of the heart – Incorrect. The apex is formed by the left ventricle, not the RV. • B. It forms the right border of the heart – Incorrect. The right atrium, not the ventricle, forms the right heart border on a chest X-ray. • C. It gives rise to the aorta – Incorrect. The left ventricle gives rise to the aorta; the RV gives rise to the pulmonary trunk. • D. It has a muscular wall that is normally thicker than that of the left ventricle – Incorrect. The left ventricle has a much thicker wall due to the high-pressure systemic circulation. Summary: The right ventricle lies on the diaphragm, so E is correct.

Answer 249

The correct answer is: E. Streptococcus pyogenes Explanation: This case describes a rapidly progressing soft tissue infection with toxicity, induration, and a vesicular rash after a minor skin injury — classic for necrotizing fasciitis, commonly caused by Streptococcus pyogenes. Streptococcus pyogenes (Group A beta-hemolytic streptococcus) is known for: • Causing rapid-onset soft tissue infections including: • Erysipelas • Cellulitis • Necrotizing fasciitis (flesh-eating disease) • Associated with toxic shock-like syndrome • Presents with: • Erythema, pain out of proportion to findings • Induration • Systemic toxicity • Rapid progression Let’s review the other options: • A. Bacillus anthracis – Causes cutaneous anthrax, which presents with a black eschar, but is painless and doesn’t usually cause rapid systemic toxicity. • B. Clostridium perfringens – Causes gas gangrene, often deeper and with crepitus from gas formation, and foul-smelling discharge. • C. Leishmania tropica – Causes cutaneous leishmaniasis, typically slow-growing, non-toxic skin ulcers; endemic to specific regions. • D. MRSA – Can cause cellulitis or abscess, but not typically associated with rapid systemic toxicity or vesicular rash unless it’s a severe variant (e.g., PVL-positive strain). Summary: Rapidly spreading, toxic soft tissue infection after minor trauma points to Streptococcus pyogenes — so E is the correct answer.

Answer 250

The correct answer is: ### **D. Sural nerve** #### **Explanation:** The **posterolateral approach** to the ankle involves an incision between the **Achilles tendon (calcaneal tendon) and the distal fibula**. The **sural nerve** is the **most at-risk structure** in this approach because: 1. **Anatomical Location:** - The **sural nerve** runs **posterior to the lateral malleolus**, closely following the **short saphenous vein**. - It courses **between the Achilles tendon and the fibula**, making it vulnerable during this surgical approach. 2. **Clinical Consequence of Injury:** - Damage can lead to **numbness or paresthesia** along the **lateral foot and heel**. - A neuroma may form, causing **chronic pain**. #### **Why Not the Others?** - **A. Deep peroneal (fibular) nerve** – Located **anteriorly** (runs with the anterior tibial artery); not near the posterolateral approach. - **B. Saphenous nerve** – Medial ankle structure (follows the **great saphenous vein**); far from the incision site. - **C. Superficial peroneal (fibular) nerve** – Courses **anterolaterally** (supplies dorsum of foot); not in the posterolateral zone. - **E. Tibial nerve** – Lies **deep and medial** to the Achilles tendon (protected in this approach unless dissection is excessively deep). #### **Key Surgical Consideration:** - The **sural nerve must be identified and protected** during the posterolateral approach to avoid postoperative complications.

Answer 251

The best answer to the question: “An abscess was resected, and a growing lesion was noted below the wound. What is the most likely diagnosis?” is: d. Pyogenic granuloma Explanation: A pyogenic granuloma is a rapidly growing, vascular lesion that commonly occurs at sites of minor trauma or surgical wounds. It appears as a red, bleeding, and friable nodule and is often mistaken for other soft tissue growths. The context of a lesion growing below a resected abscess wound fits well with this diagnosis. Let’s briefly review the other options: • Dermatofibroma: A benign fibrous nodule usually on the limbs, firm and not rapidly growing. • Keloid: Overgrowth of scar tissue beyond the original wound margin, typically firm and not rapidly growing. • Lipoma: Soft, slow-growing, benign fat tumor, unlikely to appear rapidly post-abscess. • Epidermal cyst: Subcutaneous cyst, not typically rapidly growing and wouldn’t arise so soon after wound healing.

Answer 252

The correct answer is: c. Tibial nerve Explanation: During a posteromedial approach to the popliteal fossa, such as in Baker’s cyst excision, the tibial nerve is the most superficial component of the neurovascular bundle in that area. The typical order from superficial to deep in the midline of the popliteal fossa is: • Tibial nerve (most superficial) • Popliteal vein • Popliteal artery (deepest) The common peroneal nerve lies laterally and not within the main neurovascular bundle, and the sural nerve is a superficial sensory nerve that typically lies more laterally or superficially depending on its course, and is not part of the main neurovascular bundle. The saphenous nerve is medial and more anterior, not within the popliteal fossa’s neurovascular bundle. So, during surgery, the tibial nerve is the most at risk of iatrogenic injury due to its superficial position.

Answer 253

In spinal cord hemisection (Brown-Séquard syndrome) at **C6**, the reflexes affected are typically those below the level of the lesion due to disruption of descending inhibitory pathways (leading to **hyperreflexia**). The **ankle reflex (S1)** is most commonly hyperactive due to its lower position in the spinal cord, while the **knee reflex (L2-L4)** is also hyperreflexic but may recover differently due to spinal shock resolution and plasticity. ### **Which Reflex Normalizes First?** 1. **Biceps (C5-C6)** – Since the lesion is at **C6**, the biceps reflex may be **diminished or absent initially** due to damage to the reflex arc at that level. However, if the reflex recovers, it would be **before the lower limb reflexes** because it is closer to the level of injury and may benefit from partial compensation or local reorganization. 2. **Triceps (C7-C8)** – This reflex may remain intact or become hyperreflexic later, but it is less affected than lower limb reflexes. 3. **Knee (L2-L4)** – Hyperreflexic after spinal shock, but **normalizes after the biceps/triceps** because it is farther from the lesion. 4. **Ankle (S1)** – Typically the **most hyperreflexic** and the **last to normalize** due to its low position in the cord. ### **Answer: Biceps reflex normalizes first** (if it was initially depressed due to local injury), followed by triceps, then knee, and finally ankle. - The **proximal reflexes (biceps/triceps)** tend to recover before **distal reflexes (knee/ankle)** due to their closer anatomical relation to the lesion and earlier reinnervation or compensatory mechanisms.

Answer 254

The correct answer is: C. Insulinoma Explanation: The clinical picture described — episodes of behavioral change (such as swearing and sweating) during fasting periods, which resolve after eating — strongly suggests hypoglycemia. In this case, the symptoms occur in the morning after fasting overnight, and they improve with food intake, which supports a diagnosis of insulinoma — a pancreatic islet cell tumor that secretes insulin inappropriately, leading to fasting hypoglycemia. Here’s a quick differential breakdown: • A. Dumping syndrome: Occurs post-gastrectomy; involves rapid gastric emptying, typically causing symptoms after eating, not during fasting. • B. Glucagonoma: Causes hyperglycemia, necrolytic migratory erythema, and weight loss — not episodic hypoglycemia. • C. Insulinoma: Classically presents with Whipple’s triad — symptoms of hypoglycemia, low plasma glucose, and relief of symptoms after glucose intake. • D. Reactive hypoglycaemia: Occurs after meals, particularly high carbohydrate meals — not typically during fasting. • E. Zollinger-Ellison syndrome: Gastrin-secreting tumor — presents with peptic ulcers and diarrhea, not hypoglycemia.

Answer 255

The correct answer is: B. Percutaneous needle nephrostomy Explanation: This patient presents with ureteric colic, hydronephrosis, and signs of systemic infection (fever and tachycardia). This indicates obstructive uropathy with infection, a urological emergency that requires urgent decompression of the urinary system. Here’s the reasoning behind the options: • A. Open ureterolithotomy: Rarely used today and not appropriate in the acute septic phase. • B. Percutaneous needle nephrostomy: First-line emergency intervention to relieve obstruction and drain infected urine in the presence of infection and hydronephrosis. • C. Percutaneous nephrolithotomy with JJ stent: Used for larger stones but not suitable in the acute setting of infection. Can be considered after the infection is controlled. • D. Shock wave lithotripsy (SWL): Contraindicated in the presence of infection or obstruction. • E. Ureteroscopic lithotripsy: Typically done electively; not appropriate when infection and obstruction are present. Summary: Septic obstructive uropathy must be treated with urgent decompression, and percutaneous nephrostomy is the safest and quickest way to achieve this. Once the infection is resolved, definitive stone management can follow

Answer 256

The correct answer is: a. Myositis ossificans Explanation: Myositis ossificans is a benign, localized, non-neoplastic ossification that usually develops within muscle or soft tissue, often following trauma. It’s especially common in athletes — such as martial artists — who sustain repeated blunt trauma. Key points that fit this case: • The mass is separate from the bone, meaning it’s located in the soft tissues. • There is a history of repetitive trauma or muscle injury, typical in martial arts. • Over time, the lesion becomes firm and may be mistaken for a malignancy, but imaging (especially CT or MRI) can differentiate it. Other options: • Osteosarcoma: A primary bone malignancy, arises from the bone, not separate from it. • Soft tissue sarcoma: Malignant, but less likely unless features like rapid growth, pain, or systemic signs are present. • Lipoma: Benign fat tumor, soft, non-tender, usually not post-traumatic. • Hematoma: Could be a differential, but would typically resolve or change in appearance, not ossify. Clinical Pearl: Myositis ossificans classically shows a “zoning phenomenon” on histology — central cellular area with peripheral ossification — and imaging may show calcifications maturing from the periphery inward.

Answer 257

The correct answer is: 10 cm above the radio-capitellar joint Explanation: The radial nerve originates from the posterior cord of the brachial plexus and travels posteriorly in the arm, coursing through the spiral groove of the humerus. It then pierces the lateral intermuscular septum to move from the posterior to the anterior compartment of the arm. This transition typically occurs around 10–12 cm proximal to the lateral epicondyle, or roughly 10 cm above the radio-capitellar joint, before it travels anteriorly to the lateral epicondyle and divides into its superficial (sensory) and deep (motor/posterior interosseous) branches. Breakdown of options: • Spiral groove: Radial nerve runs posteriorly here — still in the posterior compartment. • Cubital tunnel: Ulnar nerve passes here, not the radial nerve. • 10 cm above the radio-capitellar joint: Correct — where the radial nerve pierces the lateral intermuscular septum to go anterior. • 1 cm above the insertion of biceps: Not relevant to the radial nerve’s course. • None of the above: Incorrect because the correct transition point is listed.

Answer 258

The correct answer is: C. Erector spinae muscle Explanation: In patients with lumbar disc prolapse, physiotherapy aims to strengthen the core and paraspinal muscles to stabilize the spine and reduce the risk of further injury or recurrence. The erector spinae muscles are the primary extensors of the spine and play a key role in spinal support and posture. Strengthening these muscles is a central component of back physiotherapy, particularly in conditions like disc prolapse. Overview of other options: • A. Quadratus lumborum: Important in lateral flexion and lumbar stability, but not the main target in early physiotherapy. • B. Transversus abdominis: Plays a role in core stability and is part of advanced rehab, but not primarily targeted initially. • D. External oblique muscle: Assists in trunk rotation and flexion but not the primary stabilizer. • E. Latissimus dorsi: A large superficial back muscle involved in shoulder movements, not spine stability. Clinical Pearl: Rehabilitation in disc prolapse often follows a stepwise approach, starting with pain control and stabilization (targeting erector spinae and core muscles), then progressing to flexibility and posture correction.

Answer 259

The correct answer is: Serratus anterior Explanation: In the standard “safe triangle” approach for inserting an intercostal chest drain (ICD) — located at the 5th intercostal space in the anterior axillary line — the serratus anterior muscle is typically the first muscle encountered after incising the skin and subcutaneous tissue. Anatomical layers traversed: 1. Skin 2. Subcutaneous fat 3. Serratus anterior — lies superficial in this region (especially anterior to mid-axillary line) 4. External intercostal muscle 5. Internal intercostal muscle 6. Innermost intercostal muscle (if present) 7. Parietal pleura Other options: • External intercostal muscle: Deeper than serratus anterior; encountered later. • Pectoralis major: Lies more anterior and superior — not typically involved in the 5th intercostal space at the anterior axillary line. • Latissimus dorsi: Located more posterior — crossed if the incision is more posteriorly placed. • Internal oblique: Not present in the thoracic region — this is an abdominal muscle. Clinical Pearl: The “safe triangle” is bordered by: • Lateral edge of pectoralis major • Anterior border of latissimus dorsi • Line superior to the nipple (5th intercostal space) • Apex below the axilla

Answer 260

The correct answer is: Non-seminomatous testicular tumor Explanation: Alpha-fetoprotein (AFP) is a tumor marker that is characteristically elevated in non-seminomatous germ cell tumors (NSGCTs) of the testis. These include: • Embryonal carcinoma • Yolk sac tumor (especially associated with AFP elevation) • Mixed germ cell tumors Breakdown of options: • Non-seminomatous testicular tumor: Correct — AFP is elevated in these, particularly with yolk sac or embryonal components. • Seminoma: May have mildly elevated beta-hCG, but AFP is never elevated — important diagnostic point. • Benign teratoma: Usually doesn’t produce markers like AFP, especially in post-pubertal males. • Leydig cell tumor: Rare; usually does not raise AFP — may produce androgens or estrogens. • Choriocarcinoma: Characteristically raises beta-hCG, not AFP. Clinical Pearl: If AFP is elevated, the tumor cannot be a pure seminoma. This distinction is vital for diagnosis, staging, and treatment.

Answer 261

The correct answer is: 2. Lunate Explanation: Carpal tunnel syndrome (CTS) occurs due to compression of the median nerve within the carpal tunnel. The lunate bone, when dislocated or fractured, can protrude into the carpal tunnel and compress the median nerve, leading to symptoms of CTS. Breakdown of other options: • 1. Scaphoid: Fractures are common but more often affect radial artery supply and the anatomical snuffbox, not directly causing CTS. • 3. Distal ulna: Located outside the carpal tunnel, not typically associated with CTS. • 4. Distal radius: Fractures may indirectly contribute to CTS, especially with swelling, but lunate dislocation is more classically linked. • 5. Second metatarsal bone: This is a foot bone, unrelated to the carpal tunnel. Clinical Pearl: Lunate dislocation is a well-known cause of acute carpal tunnel syndrome, especially after trauma like a fall on an outstretched hand.

Answer 262

The correct answer is: E. Ultrasound scan Explanation: The first-line investigation for a thyroid lump or nodule is a high-resolution ultrasound scan. It helps to: • Confirm the presence of a nodule • Determine its size, composition (solid vs cystic), and margins • Assess for suspicious features suggestive of malignancy • Guide further investigations like fine needle aspiration cytology (FNAC) if indicated Breakdown of options: • A. CT scan: Used in cases of large goiters or suspicion of retrosternal extension/compression — not first-line for small solitary nodules. • B. Fine needle aspiration cytology (FNAC): Important diagnostic step but typically guided by ultrasound and reserved for nodules that meet certain criteria (e.g. >1 cm with suspicious features). • C. Radioiodine scan: Used to assess function of the nodule (hot vs cold) but not the first step in modern thyroid nodule work-up. • D. Thyroid antibody estimation: Useful in autoimmune thyroid disease (e.g. Graves’, Hashimoto’s) but not primary for an isolated nodule. Clinical Approach: 1. Ultrasound scan 2. Thyroid function tests 3. FNAC if nodule has suspicious features or is >1 cm and solid

Answer 263

The correct answer is: E. Visceroptotic kidney (also called a “ptotic” or “mobile kidney”) Explanation: A visceroptotic (or ptotic) kidney is an abnormally mobile kidney that descends more than normal when a person stands up. It can sometimes be palpable in the right iliac fossa, especially in thin individuals, and it moves freely with respiration and has well-defined edges, which fits the clinical description. Breakdown of the other options: • A. Appendix mass: Typically ill-defined, non-mobile, and associated with signs of inflammation (e.g. fever, pain). • B. Carcinoma of a diverticulum: Rare and would present with more systemic symptoms and not as a freely mobile mass. • C. Meckel diverticulum: Usually asymptomatic unless complications arise (e.g. bleeding, obstruction); not typically a palpable mass. • D. Mucocele of the gallbladder: Located in the right upper quadrant, not in the right iliac fossa. Clinical Pearl: A mobile mass in the right iliac fossa with clear upper and lower borders and respiratory movement in a healthy young person most commonly suggests a ptotic kidney.

Answer 264

Correct Answer: A. Activated protein C Explanation: In trauma patients, there is an early procoagulant state due to endothelial injury, inflammation, and immobilization. However, the body also activates natural anticoagulant pathways to prevent excessive clotting. Activated protein C (APC) plays a critical role in regulating coagulation. It inactivates factors Va and VIIIa, thereby downregulating thrombin generation and helping control thrombus formation. Early impairment of the protein C pathway has been linked to trauma-induced coagulopathy, highlighting its importance in modulating clot formation in trauma settings. Other options: • Plasminogen: Precursor to plasmin, involved in fibrinolysis (clot breakdown), not primary in early thrombosis control. • Fibrinogen: Clotting factor that forms fibrin; promotes thrombosis, not regulation. • Antithrombin III: Inhibits thrombin and factor Xa, but less rapidly responsive than APC in trauma. • Tissue plasminogen activator (tPA): Involved in fibrinolysis, not primary in preventing thrombosis onset.

Answer 265

Correct Answer: A. Mental nerve Explanation: The mental nerve is a branch of the inferior alveolar nerve, which itself is a branch of the mandibular division (V3) of the trigeminal nerve. The mental nerve exits the mental foramen in the mandible and provides sensory innervation to the lower lip and chin. So, numbness of the lower lip is most directly linked to damage or involvement of the mental nerve. Breakdown of other options: • B. Marginal mandibular: Branch of the facial nerve (VII); it controls muscles of facial expression, particularly around the lower lip — motor, not sensory. • C. Lingual: Provides sensation to the anterior two-thirds of the tongue and floor of mouth — not the lower lip. • D. Facial nerve: Controls facial muscles, not sensory to the lower lip. • E. Buccal nerve: Supplies sensation to the cheek mucosa and skin, not the lower lip. Clinical Pearl: Lower lip numbness — especially following dental procedures, trauma, or mandibular fractures — often suggests involvement of the mental or inferior alveolar nerve.

Answer 266

Correct Answer: A. Buccal nerve Explanation: The buccal branch of the facial nerve (cranial nerve VII) is primarily responsible for innervating the muscles of the upper lip and cheek, including: • Zygomaticus major and minor • Levator labii superioris • Buccinator These muscles are key contributors to smiling, especially the elevation of the corners of the mouth. Breakdown of other options: • B. Marginal mandibular: Controls lower lip movements (e.g. frowning or lower lip depression), not smiling. • C. Zygomatic: Also contributes to facial expression, especially the orbicularis oculi, aiding in eye closure; plays a minor role in smiling. • D. Cervical: Innervates the platysma, which affects the neck and lower face — not a major player in smiling. • E. Mental: Sensory branch (from trigeminal nerve V3), not involved in facial expression. Clinical Pearl: Damage to the buccal branch of the facial nerve (e.g., during parotid surgery) can impair the ability to smile or show teeth on the affected side. Buccal Branch: The buccal branch is a major player in smiling because it innervates muscles like the levator anguli oris, levator labii superioris, and zygomaticus major/minor, which are all involved in drawing the corners of the mouth up and back, which is essential for smiling. Zygomatic Branch: The zygomatic branch primarily innervates the orbicularis oculi muscle, which is responsible for closing the eyelids. It may also contribute to some of the same muscles involved in smiling, like the zygomaticus major and minor, but its primary role is more focused on eye closure and cheek elevation.

Answer 267

The most likely cause of a **12-year-old boy presenting with unilateral tender swelling under the angle of the mandible and fever (38.7°C)** is: ### **B. Suppurative adenitis** #### **Explanation:** - **Suppurative adenitis** (bacterial lymphadenitis) is a common cause of **unilateral, tender, swollen lymph nodes** in children, often accompanied by fever. The **submandibular or cervical lymph nodes** are frequently involved, and the condition is typically caused by **Staphylococcus aureus** or **Streptococcus pyogenes**. - **Mumps (A)** usually causes **bilateral parotid swelling** (though unilateral cases can occur early in the disease) and is less common due to vaccination. - **Submandibular tumor (C)** is rare in children and usually painless. - **Submandibular stone (D)** causes obstructive salivary gland symptoms (pain with eating, swelling near the floor of the mouth) but not fever unless secondary infection occurs. Thus, **acute bacterial lymphadenitis (suppurative adenitis)** is the most likely diagnosis. **Answer: B. Suppurative adenitis**

Answer 268

The key lab findings in this 65-year-old woman with a neck of femur fracture are: • Low calcium: 2.07 mmol/L • Low phosphate: 0.66 mmol/L • High ALP: 256 IU/L Let’s interpret this: • Low calcium + low phosphate + high ALP is a classic triad for osteomalacia. • Osteomalacia involves defective bone mineralization, often due to vitamin D deficiency. • This condition is more common in older individuals, especially women with limited sun exposure or dietary deficiency. • It predisposes to bone pain, fractures, and muscle weakness. Now, a quick look at the other options: • Bone tuberculosis: May cause localized lytic lesions but doesn’t cause this biochemical profile. • Hypoparathyroidism: Would cause low calcium but high phosphate. • Myeloma: Typically presents with hypercalcemia, lytic lesions, and normal or mildly elevated ALP. • Paget’s disease: Very high ALP, but calcium and phosphate are usually normal. Correct Answer: Osteomalacia

Answer 269

This 45-year-old man presents with hyperkalaemia (K⁺ = 6.7 mmol/L) and renal impairment (urea 18.2, creatinine 230), along with metabolic acidosis (bicarbonate 14 mmol/L). He is symptomatic with nausea, pallor, and lethargy, which could be early signs of cardiac instability or muscle weakness due to hyperkalaemia. ⸻ Step-by-step reasoning: • K⁺ > 6.5 mmol/L + symptoms is a medical emergency. • The first and most urgent priority in hyperkalaemia is to protect the heart from the potential arrhythmogenic effects of high potassium. ⸻ Correct Answer: Intravenous calcium gluconate Why? • Calcium gluconate stabilizes cardiac membranes. • It does not lower serum K⁺, but buys time to implement potassium-lowering measures. ⸻ What about the other options? • Insulin/dextrose infusion: Lowers K⁺ by shifting it intracellularly — important, but done after membrane stabilisation. • Nebulised salbutamol: Also shifts K⁺ into cells — used as adjunct. • IV bicarbonate: Helps in acidosis and mild hyperkalaemia but not as immediate or effective. • Haemodialysis: Definitive for refractory or life-threatening hyperkalaemia, but not first-line. ⸻ Summary: • 1st step: IV calcium gluconate to stabilise the myocardium. • Then: Insulin/dextrose, salbutamol, bicarbonate, and address underlying cause. • Dialysis if refractory or if renal failure is severe/progressive.

Answer 270

In a ventilated patient with a recent flail chest, who suddenly becomes hypoxic and requires increased ventilation pressures, the most likely and most common cause is: Tension pneumothorax ⸻ Why? • Flail chest often involves multiple rib fractures, which can lead to underlying lung injury, including pulmonary contusions or pneumothorax. • Positive pressure ventilation can convert a simple pneumothorax into a tension pneumothorax, rapidly causing: • Hypoxia • Raised intrathoracic pressure • Decreased venous return and hypotension • Tracheal deviation, absent breath sounds (classic signs if examined) ⸻ Other options: • Pulmonary embolism: Can cause sudden hypoxia, but not associated with increased ventilation pressures acutely. • Cardiac tamponade: Would show hypotension, distended neck veins, but not usually increased ventilation pressures. • Fat embolism: Usually occurs 24–72 hours after long bone fractures, not this acutely. • ARDS: Causes hypoxia and stiff lungs but evolves over hours/days, not suddenly. ⸻ Correct Answer: Tension pneumothorax

Answer 271

The scenario describes significant acute blood loss (1.6 L), which triggers a compensatory physiological response to maintain perfusion. ⸻ Let’s examine the responses: What will decrease? • Cardiac output: Yes – due to decreased preload (less venous return). • Firing of carotid baroreceptors: Yes – baroreceptors detect low blood pressure, leading to decreased firing. • Firing of aortic baroreceptors: Yes – also sense decreased pressure and reduce firing. • Blood pressure: Yes – falls due to hypovolemia. What will not decrease? • Renin secretion: Increases in response to low renal perfusion (via the juxtaglomerular apparatus). It’s part of the RAAS system to retain sodium and water and increase vascular tone. ⸻ Correct Answer: Renin secretion Renin secretion increases in hemorrhage to help restore circulating volume and blood pressure.

Answer 272

The loss of thumb adduction following a laceration near the base of the little finger and wrist suggests damage to the deep branch of the ulnar nerve. Key anatomy: • The deep branch of the ulnar nerve innervates the adductor pollicis, which is responsible for thumb adduction. • This nerve passes through the Guyon’s canal, and a laceration in that area can easily affect it. Other options: • Superficial ulnar nerve: Sensory only. • Median nerve: Controls thumb opposition and flexion, not adduction. • Radial nerve: Controls thumb extension. • Recurrent branch of median nerve: Supplies thenar muscles for opposition, not adduction. ⸻ Correct Answer: Deep ulnar nerve Would you like a quick diagram of hand muscle innervation?

Answer 273

In acute pulmonary embolism (PE), the ECG can show several characteristic signs due to right heart strain, but many findings are non-specific. ⸻ Common ECG findings in acute PE include: • Sinus tachycardia (most common finding) • P pulmonale (peaked P waves due to right atrial enlargement) • Right ventricular strain pattern – T wave inversions in right precordial (V1–V3) and inferior leads • S1Q3T3 pattern (classic but not always present) • T wave inversion in inferior leads (due to RV strain) ⸻ Let’s assess the options: • No changes – Often true; ECG can be normal, but this is a possible finding, so not the correct answer to “which is not a change.” • P pulmonale – Possible in PE → incorrect choice • Right ventricular strain – Very typical of PE → incorrect choice • T wave inversion in inferior leads – Seen in RV strain → incorrect choice • J waves – Also known as Osborn waves, are seen in hypothermia, not PE.

Answer 274

The scenario describes: • A 52-year-old male with central chest pain • A mitral regurgitation murmur • ECG showing ST elevation in leads V1–V6 • No ST elevation in leads II, III, and aVF These findings are classic for: Anterior myocardial infarction Reasoning: • ST elevation in V1–V6 indicates anterior wall MI, commonly due to occlusion of the left anterior descending (LAD) artery. • Absence of ST elevation in II, III, and aVF rules out inferior MI, which would suggest right coronary artery involvement. • Mitral regurgitation in this context could be secondary to papillary muscle dysfunction or rupture, a known complication of anterior MI. Correct Answer: Anterior myocardial infarct

Answer 275

The key clinical features here are: • The patient cannot lift the thumb off the table (impaired thumb extension). • There is inability to extend the interphalangeal (IP) joint of the thumb. This suggests a problem with the extensor mechanism of the thumb, particularly: Key Anatomy: • Extensor Pollicis Longus (EPL): Extends the IP joint of the thumb. • Extensor Pollicis Brevis (EPB): Extends the metacarpophalangeal joint. • Abductor Pollicis Longus (APL): Abducts the thumb. • These muscles are supplied by the posterior interosseous nerve (a deep branch of the radial nerve). Since the EPL specifically is responsible for extension of the IP joint, and the patient cannot lift the thumb off the table (which also requires EPL function), the most direct and accepted cause is: Correct Answer: A. Extensor pollicis longus tendon tear

Answer 276

The **deepest structure** in the **deep posterior compartment of the leg** is the **Flexor hallucis longus (FHL) muscle**. The deep posterior compartment of the leg contains: • Muscles: • Flexor digitorum longus (FDL) • Flexor hallucis longus (FHL) • Tibialis posterior • Neurovascular structures: • Tibial nerve • Posterior tibial artery • Peroneal (fibular) artery Anatomy insight: Among the muscles, the Flexor hallucis longus (FHL) lies laterally and deepest, close to the fibula. It passes behind the medial malleolus and is crucial for great toe flexion. • FDL is more medial and superficial than FHL. • Tibial nerve and posterior tibial artery lie between FDL and FHL. • Peroneal artery is a branch of the posterior tibial artery, traveling deeper near the fibula but not as deep as FHL. Here’s the anatomical arrangement from **superficial to deep** in the deep posterior compartment: 1. **Superficial**: **Flexor digitorum longus (FDL) muscle** (D). 2. **Intermediate**: **Tibial nerve (A)** and **Posterior tibial artery (C)** (the artery is usually lateral to the nerve). 3. **Deepest**: **Flexor hallucis longus (FHL) muscle (D)**, which lies closest to the fibula. The **Peroneal (fibular) artery (B)** is not part of the deep posterior compartment; it runs posterior to the interosseous membrane in the lateral compartment. ### **Correct Answer: D. Flexor hallucis longus muscle**

Answer 277

The phrenic nerve originates from the cervical plexus (C3–C5) and descends through the neck into the thorax to innervate the diaphragm. ### **Anatomical Relations of the Phrenic Nerve in the Thorax:** - **Right Phrenic Nerve:** - Runs **laterally to the right brachiocephalic vein and SVC**. - Passes **anterior to the root of the lung**. - **Medial structures:** **Trachea** and **esophagus** (deeper). - **Left Phrenic Nerve:** - Runs **laterally to the left subclavian artery and left common carotid artery**. - Passes **anterior to the aortic arch and root of the lung**. - **Medial structures:** **Trachea** and **esophagus** (deeper). ### **Key Point:** The **trachea** is consistently **medial** to both phrenic nerves as they descend into the thorax. ### **Answer:** **A. Trachea** *Other options:* - **B. SVC** → **Lateral to right phrenic nerve** (not medial). - **C. Esophagus** → Lies posterior to the trachea, so technically deeper but not the most direct medial relation. - **D. Subclavian artery** → **Lateral to left phrenic nerve**. - **E. Right brachiocephalic vein** → **Lateral to right phrenic nerve**.

Answer 278

In a 22-year-old woman with severe perianal Crohn’s disease and multiple anal fistulae, who: • Has had acute sepsis managed with drainage and setons, and • Is already on standard non-biological therapy (e.g., steroids, azathioprine, mesalazine) The next logical step, especially in fistulising Crohn’s, is a biological agent. Best option: • Infliximab: A TNF-alpha inhibitor, is well established in treating moderate to severe Crohn’s disease, particularly fistulising disease, including perianal fistulae. It promotes fistula healing and reduces inflammation. Other agents listed: • Trastuzumab – Anti-HER2, used in breast/gastric cancers. • Bevacizumab – Anti-VEGF, mainly used in colorectal cancer and macular degeneration. • Imatinib – Tyrosine kinase inhibitor for CML and GISTs. • Cetuximab – Anti-EGFR, used in colorectal and head/neck cancers. Correct Answer: Infliximab

Answer 279

In paediatric surgical patients, particularly children under 12 years old, the risk of venous thromboembolism (VTE) is very low unless there are additional risk factors (e.g. malignancy, immobility, central venous lines, clotting disorders). For a 5-year-old boy undergoing closure of a loop colostomy: • This is a low-risk procedure in a low-risk age group. • Routine pharmacological thromboprophylaxis is not indicated in most children unless specific high-risk factors are present. Correct Answer: None This aligns with standard paediatric surgical guidelines and practice, which emphasize mechanical methods (early mobilization) and avoiding unnecessary anticoagulation in young children.

Answer 280

Let’s evaluate each option in terms of perioperative diabetes management: 1. They should be placed first on the operating list • True: Diabetic patients are prioritized to reduce fasting time and improve glycaemic control. 2. An intravenous sliding scale should be used in all cases • False: Not all diabetic patients require an insulin sliding scale. • Minor procedures or well-controlled Type 2 diabetics on oral meds may only need monitoring and withholding oral hypoglycaemics. • Sliding scale is typically reserved for those with poor control, Type 1 diabetes, or major surgery. 3. Potassium supplementation is likely to be required in diabetics on a sliding scale • True: Insulin drives potassium into cells, often leading to hypokalaemia requiring supplementation. 4. Electrolyte abnormalities are more common after major visceral resections • True: Major surgeries, especially with bowel handling or resections, can lead to significant fluid and electrolyte imbalances. 5. Blood glucose monitoring is required during general anaesthesia • True: Essential for preventing intraoperative hypo- or hyperglycaemia, which can have significant effects on outcomes. Correct Answer (False Statement): An intravenous sliding scale should be used in all cases

Answer 281

The patient's symptoms of **loss of sensation in the lower lip** and **inability to close the mouth properly** suggest involvement of both **sensory and motor** functions in the lower face. ### Key Points: 1. **Loss of sensation in the lower lip** → **Sensory innervation** is provided by the **mental nerve**, a branch of the **inferior alveolar nerve** (itself a branch of the **mandibular division (V3) of the trigeminal nerve (B)**). 2. **Inability to close the mouth properly** → This suggests weakness of the **orbicularis oris muscle**, which is innervated by the **facial nerve (A)** (via its buccal and mandibular branches). However, the **primary nerve responsible for both symptoms** (if we consider a single lesion affecting both sensory and motor functions) would most likely be the **mandibular division (V3) of the trigeminal nerve (B)**, as it provides: - **Sensory** (via the inferior alveolar/mental nerve) to the lower lip. - **Motor** (via the mandibular branch) to the **muscles of mastication (masseter, temporalis, medial pterygoid)**, which are essential for jaw closure. The **facial nerve (A)** is primarily motor to the facial muscles (including orbicularis oris), but it does not provide sensory innervation to the lower lip. ### Why Not the Others? - **C. Accessory nerve (CN XI)** – Innervates sternocleidomastoid and trapezius; irrelevant here. - **D. Vagus nerve (CN X)** – Mainly autonomic and pharyngeal/laryngeal motor; irrelevant here. - **E. Inferior alveolar nerve** – A branch of V3, responsible for lower lip sensation but not motor function for jaw closure. ### Final Answer: **B. Trigeminal nerve (specifically its mandibular division, V3)** – A lesion here can affect both sensory (lower lip) and motor (jaw closure) functions. *(Note: If the inability to close the mouth is due to orbicularis oris weakness alone, then the facial nerve would be implicated. However, the combination with lower lip sensory loss points more strongly toward a trigeminal nerve issue, possibly at the mandibular division level.)*

Answer 282

The correct answer is: B. Orthostatic hypotension Explanation: This patient has type 1 diabetes with autonomic neuropathy, a condition that can impair autonomic control of blood pressure. One of the hallmark problems in such patients is orthostatic hypotension, which is a drop in blood pressure on standing due to impaired sympathetic vasoconstriction. • Constipation and reduced pulse rate variability are indeed features of autonomic dysfunction, but they are not typically limiting for day-case surgery. • Peripheral neuropathy is common in diabetes but does not specifically contraindicate or complicate day surgery unless it impairs mobility or causes pain. • Sinus tachycardia might be seen in autonomic neuropathy but again is usually not a problem specific to day-case surgery. Why orthostatic hypotension matters: Day-case surgeries require quick recovery and mobilization. Orthostatic hypotension poses a risk of falls and fainting, making it a significant concern postoperatively in these patients.

Answer 283

Ah, thanks for the clarification! If the question is asking which investigation is not helpful for assessing hematuria, the correct answer is: Renogram Explanation: A renogram evaluates renal function and drainage, but it does not provide anatomical detail needed to assess structural causes of hematuria such as stones, tumors, or infections. Therefore, it is not helpful in the initial diagnostic workup of hematuria. The other options are helpful: • CT KUB – good for stones. • CT Urogram – comprehensive upper urinary tract evaluation. • Ultrasound – useful first-line for kidneys and bladder. • Cystoscopy – essential for visualizing the bladder and urethra.

Answer 284

The false statement is: “It is usually treated using an endovascular approach” Explanation: • Stanford type A / Debakey types I and II involve the ascending aorta, which is a surgical emergency. • These are typically managed with open surgical repair, not endovascularly, due to the complex anatomy and proximity to the aortic valve and coronary arteries. • Endovascular repair (TEVAR) is generally reserved for Stanford type B (descending aorta) dissections. Other statements are true: • Intimal tear can indeed involve a large portion (>50%) of the circumference. • Mortality for untreated type A dissections is about 50% within 48 hours. • Arch repairs often require deep hypothermic circulatory arrest (DHCA) to protect the brain. • Blood pressure control is vital; the target systolic BP is ~100–120 mmHg to minimize shear stress.

Answer 285

The correct answer is: C. Mesenteric ischemia Explanation: • Type B dissections affect the descending aorta, and one of the feared complications is branch vessel involvement, such as the mesenteric arteries. • New abdominal pain and hypotension in this context raise concern for mesenteric ischemia, which is a surgical emergency. • Rupture is possible, but more likely in type A or if signs are chest pain with tamponade or hemothorax. • Pericardial tamponade is a complication of type A, not type B. • Myocardial infarction would be more relevant if the coronary arteries were involved (type A again).

Answer 286

The correct answer is **Luteinising hormone releasing hormone (LHRH) analogues**. ### Explanation: In the management of prostate cancer, **LHRH analogues** (e.g., leuprolide, goserelin) initially cause a **surge in testosterone** due to stimulation of luteinizing hormone (LH) release before downregulation occurs. This **testosterone flare** can worsen symptoms in patients with **spinal metastases or impending cord compression**, leading to increased pain, neurological deficits, or acute cord compression. ### Why not the others? - **Surgical orchidectomy** – Directly removes testosterone production without a flare. - **Cyproterone acetate** (an antiandrogen) – Blocks androgen receptors and suppresses testosterone without a flare. - **Flutamide** (a nonsteroidal antiandrogen) – Blocks androgen receptors and is often used to prevent flare when starting LHRH analogues. - **None of the above** – Incorrect, as LHRH analogues do carry this risk. ### Clinical Approach: In this scenario, **LHRH analogues should not be used alone** due to the risk of flare. Instead, the patient should receive: 1. **High-dose steroids** (e.g., dexamethasone) to reduce cord edema. 2. **Antiandrogen (e.g., flutamide, bicalutamide)** started **before** the LHRH analogue to block the flare effect. 3. **Consider urgent radiation/surgery** for cord compression. Thus, **LHRH analogues in isolation carry the greatest short-term risk** of worsening symptoms.

Answer 287

The correct answer is: D. L4 Here’s the breakdown: This patient presents with classic signs suggestive of lumbar nerve root compression, also known as radiculopathy. Let’s match the symptoms to the relevant nerve root: Key findings: • Pain to lateral leg: Suggests L4 or L5 • Altered sensation over the front of the knee: Typical of L4 dermatomal involvement • Reduced knee reflex: The patellar (knee) reflex is mediated primarily by L3–L4, but L4 is the main contributor • Normal hip movement with pain: Less likely to be L2/L3 which innervate hip flexors more directly Summary by spinal nerve: • L1-L2: Groin and upper thigh sensory loss; innervate hip flexors • L3: Medial thigh/knee sensory; contributes to knee reflex • L4: Anterior knee sensory, contributes to knee reflex, innervates quadriceps • L5: Lateral leg and dorsum of foot; ankle dorsiflexion and big toe extension Conclusion: The pattern most strongly points to L4 nerve root compression.

Answer 288

The correct answer is: A. T3N1M0 Let’s break this down using the TNM staging system for breast cancer: T - Tumor Size • T1: ≤ 2 cm • T2: > 2 cm but ≤ 5 cm • T3: > 5 cm • T4: Any size with extension to chest wall or skin (e.g., ulceration, peau d’orange, satellite skin nodules) This patient has a 6 cm tumor with no attachment to chest wall or skin, so it’s T3 N - Nodal Involvement • N1: Movable, ipsilateral axillary lymph nodes • N2: Fixed/matted axillary or internal mammary nodes without axillary involvement • N3: Infraclavicular/supraclavicular nodes or internal mammary nodes with axillary nodes This patient has enlarged, irregular, but not fixed or matted ipsilateral axillary nodes — this is N1 M - Metastasis • M0: No distant metastasis • Mx: Metastasis not assessed • M1: Distant metastasis present The stem says no mention of distant metastases, so M0 is appropriate. So: T3 (>5 cm), N1 (mobile axillary nodes), M0 (no distant spread) = T3N1M0

Answer 289

To calculate maintenance fluids for a child, we use the Holliday-Segar formula, which is: Daily Maintenance Fluid: • First 10 kg: 100 mL/kg/day • Next 10 kg (10–20 kg): 50 mL/kg/day • Each kg > 20 kg: 20 mL/kg/day ⸻ Step-by-step for an 18 kg child: • First 10 kg: 10 kg × 100 mL = 1000 mL • Next 8 kg: 8 kg × 50 mL = 400 mL • Total per day = 1000 + 400 = 1400 mL/day ⸻ Hourly rate = 1400 mL ÷ 24 hrs = 58.3 mL/hr Rounded, the closest correct option is: D. 56 ml/hour So the correct answer is D.

Answer 290

The correct answer is: B. Inability to rotate the face towards the right side Here’s why: This patient likely has an injury to the spinal accessory nerve (cranial nerve XI) during the supraclavicular lymph node dissection. The spinal accessory nerve innervates: • Sternocleidomastoid (SCM): rotates the head to the opposite side and flexes the neck • Trapezius: elevates (shrugs) the shoulder In this case: • Left spinal accessory nerve injury means: • Weakness in left trapezius → inability to shrug left shoulder • Weakness in left SCM → inability to turn head to the right The SCM pulls the head to the opposite side, so a weak left SCM causes inability to rotate face to the right. Other options: • A. Loss of neck flexion: Partial, not the main issue. • C. Inability to rotate face to the left: Would result from right SCM injury. • D. Loss of sensation over upper lateral shoulder: That’s axillary nerve (C5). • E. Inability to shrug the other shoulder: Wrong side. So again, the correct answer is: B. Inability to rotate the face towards the right side

Answer 291

The correct answer is: B. Radial nerve Here’s the breakdown: The neonate presents with a classic “waiter’s tip” posture, which is highly suggestive of: Erb’s palsy (Erb-Duchenne paralysis) • Caused by injury to the upper brachial plexus (C5–C6) • Commonly due to shoulder dystocia during delivery Posture: • Arm adducted → paralysis of deltoid (axillary nerve) • Forearm extended → paralysis of biceps (musculocutaneous nerve) • Forearm pronated → paralysis of supinator (C5–C6) • Wrist flexed → gravity, and flexor dominance Nerves affected (C5–C6): • Suprascapular → infraspinatus, supraspinatus (abduction, external rotation) • Musculocutaneous → biceps, brachialis • Axillary → deltoid, teres minor Nerve likely spared (intact): • Radial nerve → arises from C5–T1, but primarily C7–C8, so often spared in Erb’s palsy • It supplies elbow, wrist, and finger extensors, so extension of the wrist/fingers may still be preserved Summary: • Most upper brachial plexus nerves are affected except the radial nerve, which is intact. Answer: B. Radial nerve

Answer 292

The correct answer is: D. Thrombin injection Here’s why: A false aneurysm (pseudoaneurysm) after a femoral arterial puncture (e.g., during cardiac catheterization) occurs when blood leaks from the artery into the surrounding tissue, forming a contained hematoma with a persistent connection to the arterial lumen. ⸻ Management options: • Ultrasound-guided thrombin injection: • First-line for most iatrogenic femoral artery pseudoaneurysms • Highly effective, minimally invasive • Rapid clot formation in the aneurysm sac • Ultrasound-guided compression: • Less favored now due to pain, prolonged time, and lower success rates • Open surgical repair: • Reserved for infected, large, or complicated pseudoaneurysms • Endovascular aneurysm repair (EVAR): • Typically used for aneurysms, not pseudoaneurysms in the femoral artery • Surveillance: • Suitable for small (<2 cm), asymptomatic pseudoaneurysms only ⸻ Summary: For a symptomatic femoral pseudoaneurysm post-catheterization, the most appropriate and effective treatment is: D. Thrombin injection

Answer 293

The correct answer is: E. Thrombosis of a stenosed femoral artery ⸻ Here’s the reasoning: Key features in this case: • Bilateral calf claudication: Indicates chronic peripheral arterial disease (PAD) • New-onset acute limb ischaemia in the right foot: Suggests an acute event on top of chronic disease • No pulses below the femoral artery in either leg: Points to significant femoral artery disease bilaterally • Atrial fibrillation is present but not the main clue here — let’s explore why ⸻ Why the other options are less likely: • A. Embolism from left atrial myxoma: Rare; usually causes sudden occlusion at more distal or variable sites; would not explain bilateral PAD symptoms. • B. Embolus from left ventricular thrombus: Also possible, especially with AF or MI history, but would more likely affect a single limb unless multiple emboli. • C. Popliteal entrapment syndrome: Affects young athletes, not a 62-year-old with chronic claudication. • D. Thrombosed popliteal aneurysm: More likely to cause distal embolization with preserved femoral pulse. • E. Thrombosed stenosed femoral artery: Best fits chronic disease (claudication) now complicated by acute thrombosis → acute-on-chronic ischaemia. ⸻ Conclusion: This man had pre-existing PAD, and the acute ischaemia is best explained by thrombosis of a critically stenosed femoral artery, not embolism. Answer: E. Thrombosis of a stenosed femoral artery

Answer 294

The correct answer is: D. Left Atrium ⸻ Here’s why: A trauma located to the left of the sternum at the T5 vertebral level points to the posterior mediastinum, slightly left of midline — an area that is posterior to the heart and anterior to the vertebral column. Structures at that level: • T5 vertebral level: Approximate location of the heart’s base, particularly the left atrium • The left atrium lies posterior to the other heart chambers and is in direct contact with the anterior aspect of the esophagus and vertebral column • Therefore, trauma at this level and location risks penetrating injury to the left atrium ⸻ Other options: • A. Left ventricle: More inferior and lateral • B. Left lung: Lateral structure, not central/mediastinal • C. Left bronchus: Lies lower and more posterior, slightly lower than T5 • E. Right ventricle: Lies anteriorly, beneath the sternum, not behind it ⸻ Conclusion: The left atrium lies at the T5 level, just posterior to the sternum on the left — making it most at risk in this scenario. Answer: D. Left Atrium

Answer 295

The correct answer is: B. Often occurs in the complete absence of trauma ⸻ Here’s why: Charcot foot (Charcot neuroarthropathy) is a progressive, degenerative condition affecting the bones, joints, and soft tissues of the foot and ankle, most commonly seen in diabetic neuropathy. ⸻ Features of Charcot foot: • Peripheral neuropathy: Essential feature; leads to loss of protective sensation. • Autonomic neuropathy: Leads to increased blood flow and bounding pulses, especially in early phases. • Erythema, warmth, and swelling: Resemble infection or cellulitis, but are due to inflammation and increased perfusion. • Minor trauma or repetitive microtrauma: Often the trigger, though patients may not feel it due to neuropathy. It is not correct to say it “often occurs in the complete absence of trauma” — minor trauma, even unnoticed, typically precipitates the condition. ⸻ So, the false statement is: B. Often occurs in the complete absence of trauma

Answer 296

The correct answer is: B. Sperm granuloma ⸻ Here’s why: A sperm granuloma is a common benign complication after vasectomy. It forms when sperm leak from the cut end of the vas deferens and trigger a foreign body inflammatory reaction. ⸻ Features of a sperm granuloma: • Small, firm, often painless nodule • Located near the site of vasectomy • Occurs weeks to months post-procedure • Usually asymptomatic but may cause mild tenderness ⸻ Why the other options are less likely: • Haematoma: Would typically present soon after surgery and often with pain/swelling. • Varicocele: Feels like a “bag of worms,” typically found above the testis, not near the vas. • Hydrocele: A fluid-filled sac around the testis — would be larger, fluctuant, and transilluminate. • Epididymal cyst: Occurs in the epididymis, not adjacent to the vas; usually smooth and cystic. ⸻ Conclusion: A small nodule near the vas after vasectomy is most consistent with a sperm granuloma.

Answer 297

The most likely diagnosis for a 30-year-old male presenting with a painless swelling of the testis and histological findings of a lymphocytic infiltrate in the stroma is **Classical seminoma**. Classical seminomas are the most common type of seminoma and typically present as a painless testicular mass. They are known to have a lymphocytic infiltrate, which is a characteristic histological feature. This differentiates them from other types of testicular tumors.

Answer 298

Given that the patient already has a nephrostomy tube, the best investigation to determine the cause of hydronephrosis would be an **antegrade urethrogram**. This procedure involves injecting contrast dye through the nephrostomy tube to visualize the urinary tract and identify any obstructions or abnormalities.

Answer 299

The patient has a **flail chest** (4-5 rib fractures with paradoxical movement) and **severe hypoxemia (SpO₂ 74%)** despite high-flow oxygen (15 L/min), indicating **respiratory failure** due to inadequate ventilation. ### Key Points: 1. **Flail chest** leads to **ineffective ventilation** due to paradoxical movement and underlying lung contusion. 2. **Hypoxemia (SpO₂ 74%)** despite high-flow O₂ suggests **impending respiratory failure**, requiring **mechanical ventilation**. 3. **Other vitals are normal**, so tension pneumothorax or massive hemothorax is less likely (no need for immediate chest drain). 4. While **pain control** (options A or B) is important for flail chest, it won't resolve the hypoxemia in this case. 5. A **chest drain** (options D or E) is not indicated unless there is evidence of pneumothorax/hemothorax (e.g., absent breath sounds, tracheal deviation, hypotension). ### Best Management: **C. Intubate & assisted ventilation** - **Mechanical ventilation** stabilizes the flail segment, improves oxygenation, and prevents further respiratory collapse. - After stabilization, consider **epidural analgesia or nerve blocks** (e.g., erector spinae plane block) for pain control. ### Why Not Others? - **A/B (Bupivacaine/Lidocaine):** Pain control helps but won’t fix hypoxemia in this scenario. - **D/E (Chest drain):** Only if pneumothorax/hemothorax is confirmed (e.g., absent breath sounds, hyperresonance, or hemodynamic instability). ### Conclusion: The patient needs **immediate intubation and ventilation** due to respiratory failure from flail chest.

Answer 300

### **Question Recap:** A surgical study is comparing the risk of **colonic anastomotic leakage** between two groups: - **Group 1:** Patients who had bowel preparation. - **Group 2:** Patients who had no bowel preparation. **Sample size:** 25 total patients (small sample). **Outcome:** Anastomotic leakage (a **binary outcome**: "leak" or "no leak"). ### **Key Considerations:** 1. **Type of Data:** - The outcome (leakage) is **categorical** (yes/no). - The predictor (bowel prep) is also **categorical** (yes/no). 2. **Study Design:** - **Unpaired (independent) groups** (two separate groups, not matched). 3. **Sample Size:** - Small (n=25), so **Fisher’s exact test** is preferred over Chi-squared if expected cell counts are <5. ### **Why Fisher’s Exact Test?** - Used for **2x2 contingency tables** with small sample sizes. - Does not rely on approximations (unlike Chi-squared, which requires expected counts ≥5). - Ideal for comparing proportions in small studies. ### **Why Not the Others?** - **Paired T-test / Unpaired T-test:** Require **continuous data** (e.g., means), not binary outcomes. - **Chi-squared test:** Good for larger samples, but **inaccurate with small expected counts**. - **LSD post hoc test:** Used **only after ANOVA** (not relevant here). ### **Final Answer:** ✅ **Fisher’s exact test** is the most appropriate for comparing anastomotic leakage rates between two small, independent groups.

Answer 301

### **Clinical Scenario Summary:** - A **43-year-old woman** underwent **acute cholecystectomy** for cholecystitis. - A **surgical drain** was left in place. - Over **5 days**, the drain outputs **100-200 mL of bile per day**. - **Question:** What is the **most appropriate next step**? --- ### **Key Considerations:** 1. **Normal vs. Abnormal Postoperative Bile Drain Output:** - **Normal:** Minimal or decreasing drain output (usually <50 mL/day after a few days). - **Abnormal (Biliary Leak):** Persistent bile output (>100 mL/day beyond 3-5 days). 2. **Possible Causes of Persistent Bile Drainage:** - **Cystic duct stump leak** (most common after cholecystectomy). - **Bile duct injury** (e.g., common bile duct or right hepatic duct damage). - **Duct of Luschka leak** (accessory bile duct injury). 3. **Clinical Stability Matters:** - If the patient is **stable (no peritonitis, fever, or sepsis)**, **non-invasive management** is preferred. - If **unstable (signs of peritonitis/sepsis)**, **surgical re-exploration (laparotomy)** may be needed. --- ### **Management Options & Rationale:** #### **A. Undertake a laparotomy** - **Too aggressive** if the patient is stable. - Reserved for **severe peritonitis, sepsis, or complete ductal transection**. #### **B. Arrange an abdominal CT scan** - Can detect **fluid collections (biloma)** but **not the best for identifying bile leaks**. - Less specific than **ERCP** for biliary tree evaluation. #### **C. Arrange an ERCP (Endoscopic Retrograde Cholangiopancreatography)** - **Best next step** for **diagnosis AND treatment** of a bile leak. - **Advantages:** - Identifies the **leak site** (e.g., cystic duct stump, duct of Luschka). - Allows **stent placement** (reduces pressure and promotes healing). - **Sphincterotomy** may be performed to facilitate bile drainage. #### **D. Arrange an abdominal USS** - May show **fluid collections** but **cannot confirm bile leak origin**. - Less useful than **ERCP** for definitive management. #### **E. Order an erect CXR** - **Irrelevant** in this scenario (used for **pneumoperitoneum or chest pathology**). --- ### **Conclusion:** ✅ **C. Arrange an ERCP** - **First-line** for **stable patients** with persistent bile leak after cholecystectomy. - **Diagnostic + therapeutic** (can stent/sphincterotomize if needed). - If **ERCP fails or patient is unstable**, consider **laparotomy**. **Why not others?** - **Laparotomy** = too aggressive without signs of peritonitis. - **CT/USS** = diagnostic but not therapeutic. - **CXR** = not helpful for biliary leaks.

Answer 302

### **Clinical Scenario Summary:** - **58-year-old man** with **severe burns to hands** but **not distressed** (pain insensitivity). - **Bilateral Charcot joints** (neuropathic arthropathy). - **Loss of pain and temperature sensation** in upper limbs (dissociated sensory loss). - **Motor function preserved** (not mentioned to be affected). --- ### **Key Clues for Diagnosis:** 1. **Dissociated Sensory Loss (Pain & Temp Loss, Preserved Touch/Vibration/Proprioception):** - Suggests a **lesion affecting the spinothalamic tract** while sparing the dorsal columns. - Classic for **central cord lesions** (e.g., **syringomyelia**). 2. **Painless Burns + Charcot Joints:** - Indicates **chronic sensory neuropathy** (loss of protective sensation → unnoticed injuries). 3. **Upper Limb Predominance:** - Points to a **cervical spinal cord lesion** (e.g., syrinx expanding asymmetrically). --- ### **Differential Diagnosis & Why They Fit or Don’t Fit:** #### **A. Potts Disease of the Spine (Spinal Tuberculosis)** - Causes **vertebral destruction, kyphosis, and cord compression**. - **Not typically associated** with dissociated sensory loss or Charcot joints. - Usually presents with **pain, fever, and systemic symptoms**. #### **B. Tabes Dorsalis (Late Syphilis)** - Affects **dorsal columns** → loss of vibration/proprioception (not pain/temp). - Causes **lightning pains, ataxia, Argyll Robertson pupils**. - **Charcot joints** can occur, but sensory loss is **not dissociated**. #### **C. Transverse Myelitis** - Acute **bilateral spinal cord inflammation** → motor/sensory/autonomic deficits. - **No dissociated sensory loss** (complete or near-complete cord dysfunction). - **Not chronic** like this case. #### **D. Syringomyelia (Correct Answer)** - **Cystic cavity (syrinx) in the cervical cord** → **compresses spinothalamic fibers decussating anteriorly**. - **Classic triad:** 1. **Dissociated sensory loss** (pain/temp loss in "cape distribution"). 2. **Muscle wasting/weakness** (late, due to anterior horn cell damage). 3. **Charcot joints + painless injuries** (chronic sensory loss). - **Slow progression** fits this patient’s chronic presentation. #### **E. Subacute Degeneration of the Cord (Vitamin B12 Deficiency)** - Affects **dorsal columns + corticospinal tracts** → **loss of vibration/proprioception + spasticity**. - **No dissociated sensory loss** or Charcot joints. - Associated with **megaloblastic anemia, glossitis**. --- ### **Why Syringomyelia is the Best Fit:** 1. **Dissociated sensory loss** = **pathognomonic** for syrinx. 2. **Upper limb predominance** (cervical cord lesion). 3. **Painless burns + Charcot joints** = chronic sensory denervation. 4. **No motor deficits mentioned** (early syrinx spares corticospinal tracts). --- ### **Conclusion:** ✅ **D. Syringomyelia** - The **classic combination** of **pain/temperature loss in upper limbs + painless injuries + Charcot joints** is **diagnostic**. **Other options ruled out:** - **Tabes dorsalis** affects dorsal columns, not spinothalamic tracts. - **Transverse myelitis** is acute and non-dissociative. - **B12 deficiency** causes dorsal column + corticospinal signs. - **Potts disease** is destructive but doesn’t cause a syrinx.

Answer 303

### **Answer:** ✅ **Trachea deviated to the left** ### **Explanation:** In **traumatic aortic disruption** (typically at the **aortic isthmus**, just distal to the left subclavian artery), classic **CXR findings** include: 1. **Widened mediastinum** (>8 cm at the aortic knob) – Most common sign. 2. **Depression of the left mainstem bronchus** (due to hematoma compressing downward). 3. **Obliteration of the aortic knob** (loss of normal contour due to hematoma). 4. **Widened paraspinal interfaces** (blood tracking along the paravertebral space). ### **Why is "Trachea deviated to the left" incorrect?** - **Tracheal deviation in aortic rupture is usually to the RIGHT** (due to a left-sided hematoma pushing the trachea rightward). - **Leftward deviation is atypical** and more likely in: - **Tension pneumothorax** (trachea shifts **away** from the affected side). - **Atelectasis** (trachea shifts **toward** the collapsed lung). ### **Conclusion:** All other options are **classic CXR findings** in traumatic aortic disruption, but **tracheal deviation to the left is NOT expected** (it’s usually to the right or not present).

Answer 304

The correct answer is: E. Serum Mg²⁺ Explanation: Long-term use of ciprofloxacin, a fluoroquinolone antibiotic, is associated with several potential adverse effects, one of which is hypomagnesaemia (low serum magnesium levels). This can lead to symptoms such as muscle weakness, fatigue, and even arrhythmias or seizures in more severe cases. Magnesium is a crucial cofactor for many enzymatic reactions in the body, including those involved in muscle and nerve function. Ciprofloxacin can impair magnesium absorption and promote renal magnesium loss, especially during prolonged therapy. Other options: • Serum K⁺ and Serum Ca²⁺ might also be affected in broader contexts, but are not the most specific or sensitive markers for ciprofloxacin toxicity. • Serum Na⁺ is less commonly implicated in fluoroquinolone therapy. • Serum creatinine is useful to monitor renal function generally, but doesn’t directly indicate ciprofloxacin-induced magnesium depletion.

Answer 305

The correct answer is: D. Bilateral recurrent laryngeal nerve injury Explanation: The recurrent laryngeal nerve, a branch of the vagus nerve, innervates all intrinsic muscles of the larynx except the cricothyroid, which is innervated by the external branch of the superior laryngeal nerve. • Unilateral recurrent laryngeal nerve injury causes hoarseness of voice due to paralysis of one vocal cord. • Bilateral recurrent laryngeal nerve injury causes airway obstruction (stridor) and voice changes, because both vocal cords may lie in a midline or paramedian position, impairing airflow and phonation. This is a surgical emergency. • Superior laryngeal nerve injury, whether unilateral or bilateral, primarily affects pitch modulation, not airway patency. • Hypoglossal nerve injury affects tongue movement, not voice or airway. Given the stridor and speech difficulty post-thyroidectomy, the most likely cause is bilateral recurrent laryngeal nerve injury.

Answer 306

The correct answer is: A. Mirizzi syndrome Explanation: Mirizzi syndrome is a rare complication of longstanding gallstone disease, where a gallstone becomes impacted in the cystic duct or neck of the gallbladder, causing compression or erosion into the common hepatic duct. This leads to: • Obstructive jaundice without common bile duct stones. • Chronic inflammation and fibrosis around Calot’s triangle, making surgical dissection extremely difficult. • Colicky RUQ pain, jaundice, and mild fever (similar to cholangitis). At surgery, Calot’s triangle may be obliterated or indistinguishable due to inflammation and scarring, which matches the scenario described. Other options: • Carcinomatosis would typically involve widespread peritoneal spread, not localized fibrosis in Calot’s triangle. • Bile duct strictures usually follow previous surgery or chronic inflammation but don’t cause impaction at the cystic duct level. • Fitz-Hugh-Curtis syndrome involves perihepatitis, often from PID, and doesn’t affect Calot’s triangle. • Carcinoma of the pancreas head causes obstructive jaundice but not local inflammation around Calot’s triangle.

Answer 307

The most likely diagnosis in a 78-year-old man with a long history of shoulder pain, recent onset of weakness, impaired active abduction, but normal passive movements is: Rotator cuff tear Explanation: • Rotator cuff tears commonly occur in elderly individuals and typically present with: • Chronic shoulder pain • Weakness, particularly when attempting to abduct the arm • Impaired active range of motion, but normal passive range (since the joint itself isn’t stiff) • Osteoarthritis would likely restrict both active and passive movement. • Metastatic malignancy is less likely without systemic signs and wouldn’t typically cause isolated weakness of abduction. • Adhesive capsulitis (frozen shoulder) affects both active and passive movements due to capsular thickening. • Calcific tendonitis is usually more acutely painful and inflammatory, and not primarily associated with weakness.

Answer 308

The correct answer is: CT scan of the kidney with contrast Explanation: The clinical picture suggests metastatic bone disease. The presence of: • Widespread osteopaenia • Well-circumscribed lucent areas (also described as “punched-out” lesions) is highly suggestive of metastases, and in a young man, renal cell carcinoma (RCC) is a key consideration. RCC commonly causes: • Lytic bone lesions • Often metastasizes to bones early A contrast-enhanced CT scan of the kidney is the most appropriate modality to identify a renal primary tumor. Let me know if you’d like to review some bone pathology differentials next!

Answer 309

This clinical scenario suggests a diagnosis of Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) following a head trauma. Let’s break it down: • Serum sodium is low (128 mmol/L) — indicates hyponatremia. • Serum osmolarity is high (450 mOsm/kg) — this would typically suggest dehydration or a hypertonic state. • Urine osmolarity is low (85 mOsm/kg) — implies the kidneys are excreting dilute urine, which is inappropriate in the context of hyponatremia unless the body is trying to excrete free water. This mismatch suggests the patient has a form of “hypotonic hyponatremia with inappropriate ADH activity”, likely due to central nervous system trauma causing SIADH, or potentially cerebral salt wasting. However, the elevated serum osmolality is not typical of SIADH — more commonly, it’s low. The presence of a high serum osmolality with low sodium points more towards a hypertonic hyponatremia, which can be due to substances like mannitol or glucose that increase serum osmolality while drawing water out of cells (diluting sodium). Let’s now evaluate the options: A. Mannitol – This is an osmotic diuretic used to reduce intracranial pressure, but it can worsen hypertonic hyponatremia. B. Loop diuretics – These inhibit the Na-K-2Cl symporter and can help excrete free water; used in hypervolemic hyponatremia, not hypertonic. C. Thiazide diuretics – These are more likely to worsen hyponatremia. D. Vasopressin agonist – This would increase water reabsorption, worsening hyponatremia. Correct answer: B. Loop diuretics Explanation: The likely mechanism here is mannitol-induced hypertonic hyponatremia or trauma-related osmotic shifts. Loop diuretics can help manage this by promoting free water clearance without concentrating the urine, reducing volume overload, and correcting sodium balance.

Answer 310

This patient is post-op from an aortic aneurysm repair, now presenting with: • Nausea and vomiting • Elevated urea and creatinine — suggests acute kidney injury (AKI) • Hyperkalemia (K+ = 5.6 mmol/L) — mild to moderate Key concern: In the context of recent abdominal vascular surgery, you must consider abdominal compartment syndrome (ACS), which can cause renal dysfunction due to impaired renal perfusion. Let’s assess the options: A. Renal ultrasound – Useful to rule out obstructive uropathy, but doesn’t address the emergent post-surgical concern. B. Measurement of abdominal pressure – Highly relevant, especially with signs of AKI post abdominal surgery. C. Insulin-glucose solution – Used to shift potassium intracellularly in hyperkalemia, but 5.6 mmol/L is not yet critical; also doesn’t treat the cause. D. Hemodialysis – Reserved for severe or refractory hyperkalemia or fluid overload, not first-line here. E. Saline bolus – Could worsen abdominal pressure if ACS is present and not ideal without knowing fluid status. Correct answer: B. Measurement of abdominal pressure Explanation: After aortic aneurysm repair, abdominal compartment syndrome is a serious concern. Elevated intra-abdominal pressure impairs renal perfusion, causing AKI. Early measurement and diagnosis are critical to prevent further deterioration.

Answer 311

Correct answer: D. Attempt reduction using supination and flexion technique in the Emergency Department Explanation: This is a classic case of pulled elbow (radial head subluxation), common in children aged 1–4. It results from traction on a pronated forearm. First-line treatment is reduction by supination followed by elbow flexion, often resulting in immediate pain relief and return to normal function. Imaging is typically unnecessary unless reduction fails or there are atypical features.

Answer 312

The correct answer is: CT scan of the kidney with contrast Explanation: The clinical picture suggests metastatic bone disease. The presence of: • Widespread osteopaenia • Well-circumscribed lucent areas (also described as “punched-out” lesions) is highly suggestive of metastases, and in a young man, renal cell carcinoma (RCC) is a key consideration. RCC commonly causes: • Lytic bone lesions • Often metastasizes to bones early A contrast-enhanced CT scan of the kidney is the most appropriate modality to identify a renal primary tumor.

Answer 313

The correct answer is: C. Zygoma Explanation: This scenario describes classic features of a zygomatic bone (zygoma) fracture, also known as a tripod fracture. Key signs include: • Flat/depressed cheek – due to displacement of the zygomatic arch • Periorbital ecchymosis – from orbital floor involvement • Diplopia – often from entrapment of the inferior rectus muscle in the fractured orbital floor • Numbness over the cheek – due to involvement of the infraorbital nerve (a branch of the maxillary division of CN V), which runs through the infraorbital foramen in the maxilla but can be affected by zygoma displacement The zygomatic bone forms part of the cheek, orbital floor, and zygomatic arch, so trauma here produces this characteristic constellation of signs.

Answer 314

The correct answer is: Streptococcus viridans Explanation: Infective endocarditis in a patient with pre-existing valve disease, such as damage from rheumatic fever, is most commonly caused by low-virulence organisms like: • Streptococcus viridans group (including S. mitis, S. sanguinis, etc.) Key features: • Associated with subacute infective endocarditis • Classically affects abnormal or previously damaged valves • Commonly arises from the oral cavity (e.g. dental work, poor oral hygiene) Other options: • Staphylococcus aureus: More typical in acute infective endocarditis, especially in IV drug users or prosthetic valve infections. • Streptococcus pyogenes: Causes pharyngitis, scarlet fever, cellulitis; not typically associated with endocarditis. • Staphylococcus epidermidis: Often linked to prosthetic valve endocarditis. • Staphylococcus saprophyticus: Common cause of urinary tract infections, especially in young women.

Answer 315

The correct answer is: Intravenous naloxone Explanation: The clinical scenario is highly suggestive of opioid overdose: • History of IV drug use • Unresponsiveness • Pinpoint pupils (classic sign of opioid intoxication) Naloxone is an opioid antagonist that rapidly reverses opioid effects, including: • Respiratory depression • CNS depression • Miosis Other options: • Flumazenil: Benzodiazepine antagonist – not useful here and potentially harmful if opioids are mixed with benzodiazepines, as it can precipitate seizures. • Benhexol (procyclidine): Used for extrapyramidal symptoms – irrelevant here. • No further management: Dangerous – the patient needs immediate reversal of respiratory depression. • Glycopyrrolate: An anticholinergic – not indicated.

Answer 316

The correct answer is: B. Mastoid process Explanation: When inserting a central venous line (e.g. via the subclavian vein), an important anatomical reference is needed to guide the direction of the needle and avoid complications. • The needle is inserted just below the clavicle, aiming towards the sternal notch or the suprasternal area, but crucially it is directed medially and slightly cephalad towards the mastoid process. • This alignment helps the needle track safely under the clavicle and into the subclavian vein as it runs behind the clavicle toward the brachiocephalic vein. Mastoid process is a consistent and palpable bony landmark behind the ear that provides a helpful guide for needle orientation during central line insertion.

Answer 317

The correct answer is: Parsonage-Turner syndrome Explanation: This is a classic presentation of Parsonage-Turner syndrome, also known as brachial neuritis or neuralgic amyotrophy. Key features: • Sudden onset of shoulder pain, followed by weakness and muscle wasting • Often follows a viral illness (like glandular fever), vaccination, or even surgery • Scapular winging may occur due to involvement of nerves like the long thoracic nerve • Power is impaired in active movement due to muscle weakness, while passive movements are preserved Other options: • Adhesive capsulitis: Leads to restriction of both active and passive movement, and not typically associated with wasting. • Rotator cuff tear: May cause weakness, but not typically associated with scapular winging or recent viral illness. • Osteoarthritis: Rare in young adults and would not cause scapular winging or sudden onset. • Calcific tendonitis: Typically causes acute pain but not weakness or muscle wasting.

Answer 318

Correct Answer: B. Hemiarthroplasty Explanation: Fractures at the anatomical neck of the humerus are particularly high risk due to the disruption of blood supply to the humeral head, primarily from the anterior and posterior circumflex humeral arteries. A displaced fracture here is concerning for avascular necrosis (AVN) of the humeral head. In elderly patients, particularly over the age of 60, and especially when the fracture is displaced and involves the anatomical neck, hemiarthroplasty is often preferred. This is because: • Attempting open or closed reduction with internal fixation has a high failure rate. • Risk of AVN and non-union is significant. • Hemiarthroplasty allows earlier mobilization and reduces complication rates in this group.

Answer 319

Correct Answer: C. Mycobacterium avium intracellulare ⸻ Explanation: In patients with advanced HIV and low CD4 counts (<50 cells/mm³), Mycobacterium avium intracellulare (MAI), a non-tuberculous mycobacterium, is a common cause of generalized lymphadenopathy, especially in the setting of disseminated infection. Key features: • Systemic symptoms (fever, weight loss, diarrhoea) • Hepatosplenomegaly • Raised alkaline phosphatase • Blood cultures or lymph node biopsy confirm diagnosis ⸻ Why the others are incorrect: • A. Dermatopathic lymphadenopathy: Associated with chronic skin conditions (e.g. eczema or psoriasis), not HIV or immunosuppression. • B. Follicular hyperplasia: Seen early in HIV but not with low CD4; more typical in early or reactive lymphadenopathy. • D. Onchocerciasis: A parasitic disease common in sub-Saharan Africa, not the UK, and unrelated to HIV. • E. Sinus histiocytosis: Seen in conditions like Rosai-Dorfman disease; it’s rare and not commonly linked with HIV.

Answer 320

Correct Answer: D. Operate on the next emergency operating list ⸻ Explanation: When a young child presents with a foreign body in the external auditory canal, and multiple attempts at removal have failed, the safest and most appropriate option is to perform removal under general anaesthesia. This is to: • Prevent trauma to the ear canal or tympanic membrane • Avoid distress and injury from forced restraint • Ensure a controlled environment for safe extraction ⸻ Why not the others? • A. Manage conservatively: Not appropriate — the foreign body needs to be removed to avoid infection or hearing loss. • B. Sedation in ED: Risks incomplete sedation and movement during a delicate procedure — not safe. • C. Physical restraint: Ethically and practically inappropriate, especially after failed attempts — traumatic for the child. • E. Transfer immediately for emergency surgery: This isn’t an airway or life-threatening emergency, so immediate surgery isn’t needed unless complications arise.

Answer 321

Correct Answer: E. Platelet sequestration in the spleen Explanation: In liver cirrhosis, portal hypertension leads to congestive splenomegaly. An enlarged spleen sequesters (traps) blood cells, including platelets, leading to hypersplenism, which commonly results in: • Thrombocytopenia • Sometimes leukopenia and anaemia This is not due to destruction, but pooling and reduced release of platelets back into circulation. ⸻ Why D is not correct: • While the spleen may contribute to platelet destruction in other conditions (e.g. immune thrombocytopenic purpura), in cirrhosis-related splenomegaly, the key mechanism is sequestration, not destruction.

Answer 322

Correct Answer: B. Acute embolism Explanation: This is a classic presentation of an acute embolism: • The patient has sudden onset of distal ischemia (bluish toe, absent distal pulses). • Femoral pulses are present, which suggests proximal arteries are patent, ruling out diffuse atherosclerosis. • History of partially thrombosed aortic aneurysm raises strong suspicion for embolization of thrombus fragments from the aneurysm sac. • Diabetes may predispose to vascular disease, but the acute nature and distribution strongly point to embolism. ⸻ Why the others are incorrect: • A. Iliofemoral atherosclerosis: Would likely cause gradual claudication or reduced femoral pulse. • C. Small vessel disease: Typically affects microcirculation (like in diabetes), but wouldn’t explain sudden ischemia with absent distal pulses. • D. Buerger disease: Affects younger smokers, and involves both arteries and veins — unlikely here. • E. Deep venous thrombosis: A venous problem — doesn’t cause ischemia or pulse loss.

Answer 323

The correct answer is: C. Coracoclavicular ligament Explanation: An elevated deformity at the acromioclavicular (AC) joint following trauma is highly suggestive of a shoulder separation, which typically involves disruption of the coracoclavicular (CC) ligament. The AC joint is stabilized by: • The acromioclavicular ligament – maintains the horizontal stability. • The coracoclavicular ligament (which includes the trapezoid and conoid ligaments) – provides vertical stability. In high-grade AC separations (e.g., Rockwood types III and above), the coracoclavicular ligament is torn, leading to the characteristic “step-off” deformity with superior displacement of the clavicle. Other options: • A. Acromioclavicular ligament: Usually involved in minor injuries (e.g., Type I sprain). • B. Acromiocoracoid ligament: This ligament doesn’t exist; it might be a mix-up between other ligaments. • D. Coracoacromial ligament: Forms an arch over the humeral head, preventing superior dislocation—not involved in AC joint injuries. • E. Glenohumeral ligament: Stabilizes the shoulder joint itself, not the AC joint.

Answer 324

The correct answer is: A) Nervus spinosus Explanation: The internal acoustic meatus (also known as the internal auditory canal) transmits the following structures: • Facial nerve (CN VII) – including its nervus intermedius component • Vestibulocochlear nerve (CN VIII) – which divides into: • Vestibular nerve • Cochlear nerve • Labyrinthine artery (a branch of the anterior inferior cerebellar artery) Nervus spinosus, on the other hand, is a branch of the mandibular nerve (V3) and does not pass through the internal acoustic meatus. Instead, it re-enters the skull through the foramen spinosum along with the middle meningeal artery to supply the dura mater. So, the one that does not pass through the internal acoustic meatus is nervus spinosus.

Answer 325

The correct answer is: E. Watchful waiting Explanation: In a 70-year-old man with known prostate cancer and asymptomatic bone metastasis, particularly if limited and the patient is otherwise well, watchful waiting or active surveillance can be appropriate—especially if: • The metastases are not causing pain, fractures, or other complications. • The patient is not fit for aggressive intervention or has a limited life expectancy. • There’s no biochemical or radiological evidence of rapid disease progression. Other options: • A. Radiotherapy: Used for symptomatic bone metastases (e.g., pain, risk of fracture). • B. Morphine and C. Paracetamol (PCM): Indicated only for symptomatic pain relief. • D. Further investigation: Not routinely required if the diagnosis of bone mets is already established and the patient is asymptomatic. Hence, watchful waiting is the most appropriate initial approach here unless symptoms or complications develop.