Gastrointestinal Flashcards
(162 cards)
1
Q
What is the most likely diagnosis?
A
Achalasia (an esophageal motility disorder that results in dysphagia).
2
Q
What is the general approach to diagnosing dysphagia?
A
3
Q
What condition should be considered in an immigrant patient with this presentation?
A
Chagas disease, caused by the parasite Trypanosoma cruzi (transmitted by the reduviid bug), is indistinguishable from idiopathic forms of achalasia and should be considered in patients from endemic areas (eg, Central and South America).
4
Q
What is the pathophysiology of Achalasia?
A
Achalasia is an idiopathic motility disorder caused by impaired relaxation of the lower esophageal sphincter (LES) and loss of smooth muscle peristalsis in the lower two thirds of the esophagus. It is thought that nitric oxide–producing inhibitory neurons are lost in the myenteric plexus, resulting in the clinical picture described above.
5
Q
What other imaging or testing can help confirm this diagnosis of Achalasia?
A
- A barium esophagram demonstrates a “bird’s beak” appearance of the esophagus (Figure 7-2).
- Esophageal manometry reveals complete absence of peristalsis and failure of the LES to relax after swallowing to confirm the diagnosis.
6
Q
What is the appropriate treatment for Achalasia?
A
Pneumatic dilation of the LES provides effective but temporary relief in most patients and may need to be repeated. Surgical myotomy is also effective. In nonsurgical candidates, trials of calcium channel blockers and multiple injections of botulinum toxin in the LES are also used.
7
Q
What is the most likely diagnosis?
A
Acute pancreatitis.
8
Q
What are the common causes of this condition?
A
Acute pancreatitis occurs when pancreatic enzymes (trypsinogen, chymotrypsinogen, and phospholipase A) are activated in pancreatic tissue rather than in the lumen of the intestine, resulting in the autodigestion of pancreatic tissue. The most common causes are Gallstones (leading to common bile duct obstruction) and EtOH. Other causes include Trauma, Steroids, Mumps, Autoimmune diseases, Scorpion stings, Hyperlipidemia, and certain Drugs, including antiretrovirals (mnemonic: GET SMASHeD).
9
Q
What are the top three conditions to consider in the differential diagnosis?
A
10
Q
Why is Acute pancreatitis more common in patients with HIV infection?
A
Patients with HIV and/or AIDS are susceptible to infection with organisms such as cytomegalovirus, Mycobacterium avium complex, and Cryptosporidium, all of which can cause pancreatitis. Antiretroviral agents such as didanosine, pentamidine, and trimethoprim/sulfamethoxazole can also cause acute pancreatitis.
11
Q
What is the appropriate treatment for acute pancreatitis?
A
Most cases (85%–90%) are self-limited and resolve within 4–7 days of the start of treatment. Typical treatment for acute pancreatitis includes avoiding oral intake, aggressive intravenous fluid resuscitation, pain control, and possibly nasogastric tube placement to decrease gastric secretions in the stomach. Antibiotics are not recommended in uncomplicated pancreatitis but may be of use in severe, necrotizing pancreatitis.
12
Q
What is the most likely diagnosis?
A
Alcoholic cirrhosis of the liver. The ascites, palmar erythema, and gynecomastia all suggest liver failure. The moderately elevated transaminase levels suggest a chronic process (too many hepatocytes have already died to cause the dramatic rise seen in an acute process). Further indicators of chronicity include decreased albumin, elevated PT and PTT, thrombocytopenia, and decreased hematocrit. An AST level higher than ALT level suggests an alcoholic, rather than viral, etiology (mnemonic: ToASTed).
13
Q
What are the causes of this patient’s gynecomastia and bleeding gums?
A
The liver normally degrades estrogen. In liver failure, circulating serum levels of estrogen are higher, explaining the gynecomastia and palmer erythema. Bleeding gums are likely due to thrombocytopenia secondary to splenic sequestration and decreased platelet proliferation factor secreted by the damaged liver.
14
Q
How does ascites form?
A
Ascites (an abnormal accumulation of serous fluid in the abdominal cavity) is caused by increased intrahepatic sinusoidal pressure secondary to intrahepatic obstruction within the cirrhotic liver, decreased degradation of aldosterone by the liver leading to sodium and water retention, and decreased plasma osmotic pressure due to decreased hepatic production of albumin. Physical signs of ascites include shifting dullness, bulging flanks, and a fluid wave.
15
Q
What do the laboratory findings reveal about renal function?
A
Elevated BUN and Cr levels (BUN: Cr ratio > 20) suggest prerenal failure. The kidneys are not perfused appropriately because of decreased intravascular volume (due to ascites). Prolonged intravascular volume depletion in the setting of end-stage liver disease can cause intense renal vasoconstriction and renal failure unresponsive to volume loading; known as hepatorenal syndrome.
16
Q
What is the most likely diagnosis?
A
Appendicitis.
17
Q
What other conditions should be considered in the differential diagnosis of a 25-year-old female with abdominal pain?
A
18
Q
What is the pathophysiology of appendicitis?
A
Obstruction is often implicated as the cause of appendicitis but is not required for disease progression. The appendiceal lumen may become obstructed by a fecalith, mucosal secretions, lymphoid hyperplasia or an infectious process resulting in a distended appendix, elevated intraluminal pressure, and subsequent arterial insufficiency and tissue death.
19
Q
What is the McBurney point?
A
The McBurney point is one-third the distance from the right anterior superior iliac spine to the umbilicus; it is where the pain from acute appendicitis classically localizes once there is peritoneal irritation.
20
Q
Which antibiotics are effective for coverage of enteric organisms?
A
Ampicillin and sulbactam are empirically used to treat Escherichia coli and Bacteroides fragilis infections. Gentamicin, clindamycin, imipenem, second-generation cephalosporins, and piperacillin/tazobactam are also effective.
21
Q
What is the appropriate treatment for appendicitis?
A
Surgery is the preferred treatment, along with supportive intravenous fluids and empiric antibiotics (in case of rupture). The gold standard for diagnosis is CT scan of the abdomen with contrast; Figure 7-3 shows calcified appendicolith.
22
Q
What is the most likely diagnosis?
A
Gastroesophageal reflux disease (GERD), complicated by Barrett esophagus (Figure 7-4).
23
Q
What are the expected findings on endoscopy in a patient with Barrett esophagus?
A
ndoscopy reveals an upward shift of the gastroesophageal junction (Z line) due the metaplasia of esophageal nonkeratinized squamous epithelium to gastric columnar epithelium in the setting of recurrent acid exposure.
24
Q
What are the common treatments for uncomplicated cases of this condition?
A
- Proton pump inhibitor (PPI) trial.
- Testing for Helicobacter pylori is appropriate in patients not responsive to PPIs. Treatment with triple therapy (PPI, amoxicillin, clarithromycin) is used in H pylori–positive cases.
- Lifestyle modifications including elevation of the head of the bed, dietary restrictions, and weight loss
are often used in conjunction with medical therapy.
25
Patients with GORD and Barrett esophagus are at greatly increased risk for what other condition?
Compared to the general population, patients with Barrett esophagus are 30 times more likely to develop esophageal adenocarcinoma (lifetime risk: ∼ 5%).
26
What factors increase the risk of developing esophageal cancer?
Barrett esophagus is the major risk factor for esophageal adenocarcinoma; alcohol and cigarette smoking are major risk factors for esophageal squamous cell carcinoma. The risk factors for esophageal cancer may be remembered by the mnemonic ABCDEF: Achalasia/African American male, Barrett esophagus, Corrosive esophagitis/Cigarettes, Diverticuli (ie, Zenker diverticulum), Esophageal web/EtOH, and Familial.
27
What is the most likely diagnosis?
Choledocholithiasis (a gallstone lodged in the common bile duct). Note: The presence of gallstones is termed cholelithiasis. Gallbladder disease is common in the United States and manifests as a spectrum of disorders including asymptomatic cholelithiasis, biliary colic, cholecystitis, choledocholithiasis, and cholangitis (infection of the biliary tree). Biliary colic usually resolves within a few hours. The fact that the patient has had unremitting pain for 8 hours and mildly elevated AST and ALT suggests choledocholithiasis.
28
What physical signs of Choledocholithiasis does the patient exhibit?
- **Boas’ sign** is a radiation of pain from the inflamed gallbladder to the right shoulder.
- **Murphy’s sign** is the arrest of inspiration with deep palpation in the right upper quadrant.
29
Infection with which bacteria may result from Choledocholithiasis?
Escherichia coli, Enterobacter cloacae, Enterococ- cus, and Klebsiella are commonly implicated in in- fection of the gallbladder secondary to obstruction (cholecystitis).
30
What are the risk factors for Choledocholithiasis?
Cholesterol gallstones are most common in the United States and occur when bile is supersaturated with cholesterol, allowing crystals to form.
Risk factors for gallstones include the 4 F’s: Fat, Fer- tile, Female, and Forty. Other risk factors include oral contraceptive use, spinal cord injury, or diabe- tes mellitus, all of which cause decreased gallblad- der emptying. Intestinal and liver diseases are also risk factors.
Worldwide, pigmented gallstones are the most common form and are secondary to bile duct/gall- bladder infection, hemolysis, or impaired hepatic synthesis of bilirubin.
31
What is the pathophysiology of the patient’s pain - Choledocholithiasis?
Gallstones produce dull, poorly localized visceral pain by obstructing the ampulla of Vater or the cystic duct, causing distention of the gallbladder and irritation of surrounding structures.
32
Which structures are adjacent to the gallbladder?
The gallbladder lies immediately below the liver and above the right kidney. The cystic duct from the gallbladder joins the common hepatic duct to form the common bile duct. The common bile duct joins with the pancreatic duct and terminates in the ampulla of Vater, where bile is excreted into the duodenum.
33
What is the appropriate treatment for pain in a patient with Choledocholithiasis?
Gallstone pain is relieved when the gallstone moves back into the gallbladder, moves into the common bile duct, or passes through the ampulla of Vater. Pain of biliary colic accompanies spasms of the sphincter of Oddi; therefore, meperidine should be given for pain, as morphine causes spasms of the sphincter of Oddi.
34
The hepatoduodenal ligament includes which three structures?
Three structures run through the hepatoduodenal ligament (Figure 7-5):
1. The portal vein brings blood from the digestive tract to the liver.
2. The hepatic artery brings oxygen and nutrients to the liver.
3. The common bile duct connects the liver and gallbladder to the small intestine.
35
What is the most likely diagnosis?
Crigler-Najjar syndrome.
36
What is the pathophysiology of Crigler-Najjar syndrome?
This is an inherited disorder of bilirubin metabolism, resulting from a mutation in glucuronyl transferase, the enzyme that conjugates bilirubin with glucuronic acid. Unconjugated bilirubin is less water soluble than conjugated bilirubin. It is therefore less easily excreted in urine/bile and deposits throughout the body, as evidenced in this patient by jaundice and scleral icterus.
37
What are the two subtypes of this condition, and how do they differ in severity?
- Crigler-Najjar type I: Glucuronyl transferase activity is completely absent, which results in a high likelihood of death in the first year of life.
- Crigler-Najjar type II: Glucuronyl transferase activity is present but low. Patients with this form of the disease have a better prognosis than those with type 1 (Table 7-1).
38
Patient's with Crigler-Najjar syndrome are at risk for what life-threatening complication?
Kernicterus is an abnormal accumulation of bile pigment in the basal ganglia of the central nervous system leading to deranged motor function, irreversible brain damage, and even death. Unconjugated bilirubin also penetrates the blood-brain barrier to cause neuronal death.
39
What is the appropriate treatment for Crigler-Najjar syndrome?
In Crigler-Najjar type I, liver transplantation is the only cure. Phototherapy may prevent kernicterus. In type II, hyperbilirubinemia often responds to phenobarbital.
40
What is the most likely diagnosis?
Diverticulitis (inflammation of outpouchings involving all layers of the colonic wall). The patient has known diverticula in her distal colon as seen in her roentgenogram. The previous GI bleed was likely secondary to a diverticular bleed.
41
Which of the clinical signs and symptoms help confirm the diagnosis of Diverticulitis?
Constipation, flatus, left-sided abdominal pain, tenderness, fever, tachycardia, and elevated WBC count are characteristic of diverticulitis.
42
What tests can help confirm the diagnosis of Diverticulitis?
X-ray of the abdomen is needed to rule out free air (a surgical emergency in which upright x-ray of the abdomen shows an area of lucency immediately under the diaphragm caused by diverticular rupture). If there is no surgical emergency, a CT of the abdomen may be ordered. Radiographic findings include bowel wall thickening, fistulas, and/or abscesses. Colonoscopy is contraindicated in acute cases as it may cause perforation but should be completed on follow-up to evaluate for malignancy.
43
What are the risk factors fordiverticulitis, and what steps can prevent recurrence?
Advanced age, chronic constipation, previous diverticulosis, and aspirin use all heighten the risk for diverticular disease. A high-fiber diet and good hydration reduce the risk of developing diverticula and subsequent diverticulitis.
44
What is the appropriate treatment for diverticulitis?
Treatment includes broad-spectrum antibiotics, such as metronidazole and ciprofloxacin, a clear liquid diet for 1 week, and adequate analgesia. A follow-up colonoscopy should be performed after the acute symptoms resolve.
45
Where should this patient be placed on the triage list?
This patient requires immediate attention. Even without laboratory data, her vital signs (fever, tachycardia, hypotension, and tachypnea) and toxic appearance raise suspicion of infection.
46
What is the most likely diagnosis?
Cholangitis is an infection of the bile ducts secondary to ductal obstruction (Figure 7-7). Most commonly, the common bile duct is obstructed by a gallstone. Other causes include stricture, biliary cancer, and infection (eg, Clonorchis).
47
How does the physical examination help confirm the diagnosis of Cholangitis?
The patient displays Charcot triad (RUQ pain, jaundice, and fever) and Reynolds pentad (Charcot triad plus hypotension and mental status changes), which are classic for cholangitis.
48
What risk factors in this patient’s history predisposed her to cholangitis?
The patient likely has underlying cholelithiasis (gallstones). In addition to the 4 F’s (Fat, Fertile, Forty, and Female), the patient also has hereditary spherocytosis (HS). Patients with HS are predisposed to develop pigment gallstones due to chronic hemolysis. Pigment gallstones are radiopaque because they are composed of calcium bilirubinate. The high iron content from the hemolyzed red blood cells may also help these stones to be visualized on x-ray.
49
What laboratory values are expected in a patient with cholangitis?
50
What is the appropriate treatment for cholangitis?
This patient is displaying severe symptoms, so every effort should be made to relieve the obstruction and decompress the biliary tree. Endoscopic retrograde cholangiopancreatography (ERCP) is the tool of choice, as it is both diagnostic and therapeutic.
51
What is the most likely diagnosis?
Esophageal atresia with tracheoesophageal fistula. This variant accounts for 85% of these malformations (Figure 7-8).
52
What is the mechanism of polyhydramnios?
Normally, fetuses swallow amniotic fluid in utero. The fluid is absorbed by the infant’s GI tract and returned to the mother via the placenta or eliminated through the urinary system. When a fetus is unable to swallow, amniotic fluid builds up, resulting in polyhydramnios. Polyhydramnios can also result from disorders of the urinary tract, as in neonatal Bartter syndrome.
53
Lung buds are derived from which embryonic structure?
The lung buds, which will become the bronchial tree, begin as evaginations from the primitive foregut, which also gives rise to the esophagus. Thus, abnormalities anywhere along this developmental pathway can cause a variety of tracheoesophageal fistulae.
54
Which pathogens are most likely to cause pneumonia in a patient with Esophageal atresia with tracheoesophageal fistula?
Anaerobes are likely to cause pneumonia because of the increased risk of aspiration of GI contents from frequent vomiting and pooling of fluids in the esophageal pouch.
55
What congenital condition is associated with polyhydramnios and bilious vomiting?
Duodenal atresia, which has an increased incidence in infants with trisomy 21 (Down syndrome). Bilious vomiting indicates gastrointestinal obstruction distal to the opening of the bile duct.
56
This patient should be screened for what other congenital abnormalities?
57
What is the most likely diagnosis?
Gastrinoma, a gastrin-secreting, non–β islet cell tumor of the pancreas or duodenum. These tumors cause gastric hypersecretion of hydrochloric acid, which results in disseminated gastrointestinal ulcers.
58
What test can further support the diagnosis of gastrinoma?
The secretin stimulation test elicits increased gastrin secretion by the cells in a gastrinoma, whereas normal gastric G cells are inhibited by secretin. The test therefore differentiates between the presence of a gastrinoma and other causes of hypergastrinemia.
59
What are the two most common neuroendocrine tumors?
Gastrinoma (two-thirds are malignant) and insulinoma (usually benign) are the most common neuroendocrine tumors.
60
What are 6 signs and symptoms of gastrinoma?
1. Increased fasting gastrin level.
2. Ulcers in unusual locations such as the proximal jejunum.
3. Gastroesophageal reflux disease.
4. Nausea/vomiting.
5. Epigastric pain.
6. Weight loss.
61
With what syndromes is gastrinoma commonly associated?
- Zollinger-Ellison (ZE) syndrome is characterized by a classical triad of symptoms: increased gastric acid secretion, peptic ulcer disease, and diarrhea.
- Multiple endocrine neoplasia type I (MENI) is a genetic syndrome with an increased risk of parathyroid, pituitary, and pancreatic (such as gastrin-secreting) adenomas.
62
What is the appropriate treatment for gastrinoma?
Surgical treatment involves resection of the tumor, surrounding pancreatic tissue, regional lymph nodes, and other structures in cases of metastasis (60%).
Medical treatments include proton pump inhibitors and somatostatin. Octreotide is a somatostatin analog with a longer half-life. Both somatostatin and octreotide act by inhibiting release of somatotropin, insulin, gastrin, glucagon, and vasoactive intestinal peptide.
63
What is the most likely diagnosis?
Symptoms suggest hemochromatosis, which has a classic triad of features:
1. Micronodular pigment cirrhosis.
2. Diabetes mellitus.
3. Skin pigmentation.
The last two symptoms give this disease the nickname “bronze diabetes.”
64
How is Hereditary (primary) hemochromatosis inherited?
Hereditary (primary) hemochromatosis is an autosomal recessive disease caused by a defect in the Hfe gene of chromosome 6.
65
What is the pathophysiology of Hereditary (primary) hemochromatosis?
In the primary disorder, the mutant Hfe gene alters transferrin regulation, leading to excess storage of iron in the parenchymal cells of visceral organs. The organs most affected are as follows:
- Liver, leading to cirrhosis. Liver biopsy typically shows extensive hemosiderin deposits within the hepatocytes and Kupffer cells (specialized macrophages). Hemosiderin and other iron-containing compounds stain with Prussian blue.
- Pancreas, leading to diabetes mellitus.
- Heart, leading to restrictive cardiomyopathy and congestive heart failure.
- Joints, leading to arthritis and arthralgias.
- Gonads, leading to testicular atrophy.
66
What is the appropriate treatment for Hereditary (primary) hemochromatosis?
Treatment involves repeated phlebotomy and an iron chelator such as deferoxamine.
67
How is Hereditary (primary) hemochromatosis differentiated from Wilson disease?
68
What is the most likely diagnosis?
What laboratory findings support the diagnosis?
Hepatitis B virus (HBV) infection.
69
What percentage of patients with an acute Hep B infection progress to a chronic form?
Approximately 10% of adults with acute HBV infection develop chronic hepatitis, whereas 90% of affected neonates develop the chronic disease.
70
What are 3 appropriate treatments for Hep B?
1. Lamivudine (3TC) is phosphorylated into a nucleotide analog and leads to DNA chain termination.
2. α-Interferon, an endogenous cytokine, has a high efficacy but can be expensive and has side effects (headache, nausea/vomiting, liver/renal toxicity with chronic use).
3. Adefovir is a nucleotide analog of adenosine monophosphate and therefore stops DNA replication. It is
often used in cases of lamivudine-resistant chronic hepatitis.
71
Was the third antibody test falsely positive? Why or why not?
No, this student has acute HCV infection. It takes weeks to months for the body to develop an antibody response to HCV (Figure 7-9). The two prior negative tests indicated only that he did not have a pre- existing HCV infection or prior exposure.
72
What other laboratory findings are typically found in patients with acute HCV infection?
Transaminitis (elevated AST and ALT) secondary to damaged liver cells releasing intracellular enzymes is common. HCV RNA may also be detectable in the serum by reverse transcriptase–polymerase chain reaction.
73
What is the course of acute Hep C infection?
The majority of patients with acute HCV infection are asymptomatic. Approximately 25% of patients will become jaundiced. The patient may have flulike symptoms lasting 2–12 weeks. Although only a small percentage of people exposed to HCV by needlestick will develop acute hepatitis, 60%–80% of those who develop acute hepatitis will develop chronic infection. Chronic infection has a variable but slowly progressive course; approximately 20% of patients develop cirrhosis. Excessive alcohol consumption further increases the risk of cirrhosis in this patient population.
74
What are the appropriate treatments for acute Hep C?
A combination of ribavirin and pegylated α-interferon induces remission in approximately 40% of chronic, active HCV cases. Ribavirin is a guanosine analog that inhibits viral mRNA synthesis. Pegylated α-interferon is an endogenous cytokine that induces antiviral host enzymes and causes significant flulike symptoms.
75
What is the likely diagnosis?
Hepatocellular carcinoma (HCC), also known as hepatoma. (Do not let the “oma” fool you into thinking that this tumor is benign.)
76
What are 5 risk factors associated with Hepatocellular carcinoma (HCC)?
1. Chronic hepatitis B and C infection.
2. Cirrhosis.
3. Aflatoxin (produced by Aspergillus flavus).
4. Heavy metal disorders with liver deposition (Wilson disease, hemochromatosis).
5. α1-Antitrypsin deficiency.
77
What serum marker may help diagnose Hepatocellular carcinoma (HCC)?
α-Fetoprotein (AFP). This is not specific for HCC, as elevated serum AFP also occurs in pregnancy, germ cell tumors, and other liver diseases; however, for Step 1, hepatic tumor + AFP = hepatoma.
78
How can the physical examination findings be explained?
79
What nutritional deficiencies are likely to be present in alcoholic patients?
80
What role does thiamine play in the metabolism of carbohydrates and amino acids?
Thiamine is present in cells as thiamine pyrophosphate (TPP), which is necessary for the metabolism of pyruvate to acetyl-CoA, and α-Ketoglutarate to succinyl-CoA in the process of aerobic cellular respiration. Thiamine is also used for the oxidative decarboxylation of branched-chain amino acids (leucine, isoleucine, and valine) and the pentose-phosphate shunt.
81
Why must alcoholics receive thiamine whenever glucose-containing intravenous fluids are given?
This is done to prevent Wernicke encephalopathy. Thiamine is necessary for the metabolism of glucose. There is a high level of TPP in the mammillary bodies. If glucose is administered, the remaining thiamine in the mammillary bodies is consumed, leading to irreversible damage. The triad of Wernicke encephalopathy is confusion, ataxia, and ophthalmoplegia (nystagmus). Korsakoff syndrome is a permanent condition with an etiology similar to Wernicke encephalopathy and characterized by both retrograde and anterograde amnesia with confabulation.
82
- What is the most likely diagnosis?
- Is this patient’s condition likely due to biliary obstruction?
- The patient is given phototherapy. Why is this effective?
- Hyperbilirubinemia due to red cell lysis caused by maternal anti-B antibodies (immunoglobulin G) in the infant’s blood.
- No; it is not likely to be caused by biliary obstruction because the infant’s direct bilirubin level is 0 mg/dL, indicating that conjugated bilirubin is being excreted properly.
- Phototherapy irreversibly converts unconjugated bilirubin into lumirubin, which is similar to conjugated bilirubin in that it is soluble and able to be excreted in bile and urine.
83
The patient is given a blood transfusion for his anemia. What ABO blood types should the packed RBC donor and the plasma donor be to minimize hemolysis upon transfusion?
The RBC donor should be type O to avoid hemolysis of donor cells by maternal anti-B antibodies in the infant’s blood. The plasma donor should be type B or AB, so that the plasma will not contain anti-B antibodies, which would be incompatible with the infant’s blood.
84
Which drugs, when ingested by the mother, increase the baby’s risk of kernicterus?
Drugs that are highly bound to albumin—such as aspirin, ceftriaxone, and sulfa-based drugs—may displace bilirubin from albumin, thus increasing the level of neurotoxic free bilirubin in the blood and leading to the development kernicterus.
85
Despite phototherapy, the infant’s total serum bilirubin climbs to 26 mg/dL. An infusion of albumin followed by an exchange transfusion is ordered. Why is this treatment effective?
Infused albumin binds free bilirubin, helping to draw extravascular bilirubin from tissues into the blood, which will then be removed by the exchange transfusion.
86
What is the most likely diagnosis?
An inflammatory bowel disease. In this case, ulcerative colitis (UC) is more likely than Crohn disease (CD) because of the genetic component, associated joint/lower back pain, and gross appearance.
87
How can Ulcerative colitis be differentiated from Crohn's disease (CD)?
88
What extraintestinal manifestations are possible in this patient with ulcerative colitis (UC)?
Extraintestinal manifestations in UC relate to its association with HLA-B27: ankylosing spondylitis, reactive arthritis (ie, arthritis, uveitis, urethritis), primary sclerosing cholangitis, and pyoderma gangrenosum. Patients with primary sclerosing cholangitis have an even greater risk of colorectal cancer (CRC).
89
What further screening is recommended for the future in patient's with ulcerative colitis?
There is a significantly increased risk of CRC among patients with UC. The risk depends on duration and extent of disease, especially at 8–10 years after onset of symptoms. Patients should undergo colonoscopy and biopsy approximately 8 years after first diagnosis and, if negative, undergo a repeat examination every 1–3 years thereafter.
90
Where is the likely origin of the blood?
The blood is most likely from the lower gastrointestinal (GI) tract. Hematochezia (maroon or bright red blood/clots per rectum) is a hallmark of a lower GI bleed. Hematemesis (vomiting of blood or coffee grounds–like material) and/or melena (black, tarry stools) are characteristic of an upper GI bleed. While this distinction is not absolute, it is a good rule of thumb.
91
What are the top three conditions that should be considered in the differential diagnosis?
1. **Diverticulosis** (characterized by outpouchings of the colonic mucosa with bleeding due to vessel wall weakness).
2. **Neoplasm** (polyp, carcinoma).
3. **Angiodysplasia** (small vascular malformation).
92
What is the most likely cause of this patient’s bleeding?
Diverticulosis. The most common causes of acute lower GI bleeding are diverticulosis (33%), cancers/ polyps (19%), colitis/ulcers (18%), angiodysplasia (8%), and anorectal/hemorrhoids (4%). By 85 years of age, approximately 65% of the population has diverticula. Hemorrhoids should be suspected in a younger patient.
93
What is the pathophysiology of Diverticulosis?
Diverticulosis occurs when diverticula form, exposing the surrounding arterial vasculature to injury and causing thinning of the media. This predisposes to rupture, arterial bleeding, and rapid loss of blood per rectum. This is in contrast to angiodysplasia, which can cause venous intestinal bleeding. Although most diverticula form in the left colon, right-sided diverticula are more likely to bleed. Risk factors for diverticular formation include nonsteroidal anti-inflammatory drugs, lack of dietary fiber, older age, and constipation.
94
What is the initial diagnostic test for diverticulosis?
Colonoscopy can be both diagnostic and therapeutic. The urgency of colonoscopy is based on the amount of blood produced and surrogate markers of the briskness of the bleed such as blood pressure and orthostatic hypotension. Additional tests include radionuclide imaging (radiologic monitoring of radionuclide tagged red blood cells to determine site of bleeding) and mesenteric angiography.
95
What is the most likely diagnosis?
Intussusception is the telescoping of one portion of the bowel (often at the ileocecal junction) into another. This process can lead to luminal obstruction and vascular compromise.
96
What are the common causes of Intussusception?
1. Anatomical causes include Meckel diverticulum or polyp/tumor.
2. Infectious causes include adenovirus, rotavirus vaccine, enteric bacteria.
3. Vasculitic causes include Henoch-Schönlein purpura.
97
What is the embryonic origin of a Meckel diverticulum?
A Meckel diverticulum is the most common congenital abnormality of the small intestine, resulting from failure of the vitelline duct to close. The role of the vitelline duct is to connect the developing midgut to the yolk sac. Normally, the duct closes and obliterates by approximately 7 weeks’ gestation.
98
What are the classic characteristics of a Meckel diverticulum?
99
What explains the patient’s temperament on presentation?
Intussusception makes the child irritable. The classic presentation on the boards will be an inconsolable child with a sausage-like palpable abdominal mass and “currant-jelly” stools. Children may appear completely well between episodes of obstruction. Patients often curl into a ball in an effort to reduce the intussusception. A barium enema can be both diagnostic and therapeutic.
100
What is the cause of the bright red rectal bleeding?
The two most common tissue types found in a Meckel diverticulum are gastric (80%) or pancreatic (∼ 20%). The heterotopic gastric tissue releases gastric enzymes into the surrounding sensitive intestinal mucosa, which can lead to ulceration, pain, and bleeding.
101
Is a Meckel diverticulum a true or false diverticulum?
This is a true diverticulum, in that it involves all layers of the intestinal wall (Figure 7-11).
102
What is the most likely diagnosis?
Primary hepatocellular carcinoma (HCC). Incidence of HCC is increased in patients with HCV who develop cirrhosis. By contrast, patients who are infected with hepatitis B virus may develop HCC without cirrhosis.
103
What is the blood supply to the liver?
The liver is supplied by the portal vein (75% of blood flow) and hepatic artery. Branches of these vessels divide the liver into the left and right lobes. Efferent blood is carried from the hepatic vein to the inferior vena cava. Portal hypertension occurs when blood flow through the liver is obstructed, often due to cirrhosis.
104
How does the fetal blood supply to the liver differ from the adult blood supply?
The umbilical vein is the major blood supply to the fetal liver and provides nutrients to the developing fetus. The umbilical vein enters the fetus via the umbilicus and then joins the left portal vein. A small amount of placental blood perfuses the liver. Most placental blood, however, bypasses the liver via the ductus venosus and joins the left hepatic vein. The left hepatic vein then empties into the inferior vena cava and ultimately the right atrium. The umbilical vein and ductus venosus disappear 2–5 days after birth, becoming the ligamentum teres and ligamentum venosum, respectively.
105
What is the falciform ligament and where is it located?
During development, the falciform ligament connects the portion of the primitive foregut that will form the liver to the anterior abdomen at the umbilicus. This connection enables the umbilical vein from the placenta to enter its free border at the umbilicus and reach the portal vein at the porta hepatis. The falciform ligament on the anterior surface of the liver divides the liver into the left and right anatomic lobes.
106
Why does this patient have increased abdominal girth?
The increased abdominal girth is likely due to ascites, or excess peritoneal fluid, resulting from portal hypertension and a failing liver. In liver failure, albumin production falls, decreasing oncotic pressure within vessels. Transudative fluid leaves vessels as a result of the relative increase in hydrostatic pressure (Starling forces).
107
What calculation can differentiate transudative from exudative causes of ascites?
108
What is the most likely diagnosis?
Vitamin B3 (niacin) deficiency. This is commonly known as pellagra and is characterized by the 3 D’s: dementia, diarrhea, dermatitis.
109
What is the function of vitamin B3?
Niacin is a precursor for oxidized nicotinamide adenine dinucleotide (NAD+) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). NAD helps carry reducing equivalents away from catabolic processes, such as oxidative phosphorylation. NADPH is used as a supply of reducing equivalents in anabolic reactions, such as the biosynthesis of steroids and fatty acids to maintain reduced glutathione, and in the oxygen-dependent respiratory burst of macrophages.
110
From what amino acid is vitamin B3 derived?
Tryptophan
111
What are the most likely causes of this presentation?
In developed nations, pellagra is seen most commonly in alcoholics (due to malnutrition). It can also be seen in patients with Hartnup disease (a disorder of tryptophan absorption) and carcinoid syndrome (in which there is increased conversion of tryptophan to serotonin). Isoniazid inhibits the conversion of tryptophan to niacin; therefore, patients receiving isoniazid are often prescribed niacin replacement.
112
What are the symptoms of overdose of vitamin B3?
Prostaglandin-mediated flushing is a symptom seen in overdose. Patients receiving niacin as a treatment for hypertriglyceridemia may experience this adverse effect. Prophylaxis with aspirin often prevents this reaction.
113
What is the most likely diagnosis?
Primary biliary cirrhosis (PBC) is a presumed autoimmune disease with destruction (inflammation and necrosis) of the intrahepatic bile ducts.
114
What are the signs and symptoms of Primary biliary cirrhosis (PBC)?
The most common symptoms are fatigue (65%) and pruritus (55%) in a woman 40–60 years of age. Jaundice and xanthelasma are fairly rare (∼ 10%).
115
What laboratory tests support the diagnosis of Primary biliary cirrhosis (PBC)?
What additional laboratory tests should be ordered?
Most patients are diagnosed by routine laboratory tests: increased alkaline phosphatase, GGT, and bilirubin (total and direct). AST and ALT are characteristically normal.
Antimitochondrial antibodies should also be ordered. There may also be an increase in the erythrocyte sedimentation rate and serum immunoglobulin M levels.
116
What other conditions may be present in patients with Primary biliary cirrhosis (PBC)?
Other autoimmune diseases, such as scleroderma, Sjögren syndrome, and rheumatoid arthritis may coexist with PBC. Up to 50%–75% of patients with PBC present with sicca syndrome—dry eyes (xerophthalmia) and dry mouth (xerostomia)—commonly seen among Sjögren patients.
117
What is the appropriate treatment for the patient’s pruritus in Primary biliary cirrhosis (PBC)?
Antihistamines.
118
What is the appropriate treatment for Primary biliary cirrhosis (PBC)?
Ursodeoxycholic acid (ursodiol). Methotrexate may be added in severe cases.
119
How is Primary biliary cirrhosis (PBC) distinguished from primary sclerosing cholangitis?
Primary sclerosing cholangitis is more likely in males; affects both intrahepatic and extrahepatic bile ducts; shows negative anti-mitochondrial antibodies; and is associated with ulcerative colitis.
The classic description of endoscopic retrograde cholangiopancreatography findings of the bile ducts is “pearls on a string” or “bile lakes.”
120
What is the most likely diagnosis?
This is a typical presentation of pseudomembranous colitis, which is notorious among hospitalized patients who receive clindamycin. Confirmatory findings include the presence of fecal leukocytes, anorexia, and dehydration.
121
What is the causative organism of pseudomembranous colitis?
Clostridium difficile. This anaerobic gram-positive rod becomes predominant in the bowel after normal flora have been killed off by broad-spectrum antibiotics, such as clindamycin, penicillins (especially ampicillin), and cephalosporins.
122
What is the underlying pathophysiology of C difficile?
C difficile releases two exotoxins (proteins A and B) that bind to receptors on intestinal epithelial cells. These toxins cause sloughing of epithelial cells into the lumen and mucosal ulceration. A pseudomembrane forms, composed of inflammatory cells, proteins, and mucus (Figure 7-12).
123
What are other manifestations of infections with C difficile?
Infection with C difficile can result in a broad spectrum of symptoms, ranging from asymptomatic to fulminant colitis. Antibiotic-associated diarrhea can be mild or profuse and can occur with or without colitis. The colitis itself can appear pathologically nonspecific or can demonstrate pseudomembranes. Fulminant colitis can result in toxic megacolon (potentially lethal nonobstructive colonic dilation) or even perforation.
124
What are the appropriate treatments for pseudomembranous colitis secondary to C difficile?
First-line therapy for pseudomembranous colitis is oral metronidazole. Intravenous metronidazole can be used in serious cases. Oral vancomycin can also be used to treat severe C difficile enterocolitis, as it predominantly remains in the gut; however, both vancomycin and metronidazole have also been implicated as causes of pseudomembranous colitis.
125
What is the most likely diagnosis?
What findings support this diagnosis?
Hypertrophic pyloric stenosis (Figure 7-13).
This patient demonstrates the classic presentation of pyloric stenosis with immediate postprandial, nonbilious, often projectile vomiting (“the hungry vomiter”) and a palpable olive-like mass in the epigastrium. Firstborn white males are more at risk than other populations.
126
What are the typical laboratory findings in Hypertrophic pyloric stenosis?
Hypochloremic metabolic alkalosis from the loss of large amounts of gastric hydrochloric acid is seen with pyloric stenosis. Unconjugated hyperbilirubinemia may also be seen.
127
How is the diagnosis of Hypertrophic pyloric stenosis confirmed?
Diagnosis is straightforward when the “olive” is palpable. Otherwise, it may be difficult to distinguish this condition from gastroesophageal reflux without an ultrasound or upper gastrointestinal series. The latter may demonstrate an elongated pylorus (“string sign”) with a tapered end (“beak sign”).
128
What is the appropriate management for Hypertrophic pyloric stenosis? Given appropriate management, what is the prognosis?
The definitive management is surgery (pyloromyotomy).
Patients can be expected to make a complete recovery, including return to normal weight and growth.
129
What other conditions are commonly associated with Hypertrophic pyloric stenosis?
Associated conditions include hiatal hernia, midgut volvulus, gastroesophageal reflux, and esophageal atresia.
130
What is the most likely diagnosis? What drug did the mother likely administer to the patient?
Reye syndrome. Although extremely rare, this diagnosis is devastating if missed (and is a board favorite).
Aspirin. Always suspect Reye syndrome in a child who has altered mental status, vomiting, and has suffered a recent viral illness.
131
What other laboratory findings are expected in this patient?
132
What is the pathophysiology of Reye syndrome?
It is thought that salicylate metabolites during viral infection damage mitochondria and/or that susceptible individuals have an underlying polymorphism in mitochondrial function. Mitochondrial dysfunction leads to increased short-chain fatty acids, hyperammonemia, and cerebral edema, although the exact mechanism is unclear.
133
What is the association between the patient’s recent flulike symptoms and the current presentation of Reye syndrome?
Although the etiology of Reye syndrome is unknown, the condition typically occurs after a viral infection, particularly an upper respiratory tract infection, influenza, varicella, or gastroenteritis, and is associated with aspirin use during the illness.
134
What is a possible explanation for the child’s change in mental status?
135
Despite treatment, the patient dies. What pathologic findings are expected in Reye syndrome?
Microvesicular fatty change (steatosis) of the liver, kidneys, and brain may be seen on autopsy.
136
What condition explains the patient’s inability to thrive solely on enteral feeding?
Short bowel syndrome due to extensive bowel resection leading to malabsorption.
137
After resection of the ileum, which specific molecules will be malabsorbed?
Vitamin B12 and bile salts are absorbed exclusively in the ileum and thus are deficient in short bowel syndrome.
138
The remainder of the patient’s jejunum has adapted by increasing the number of cells in the villi, thereby lengthening the villi. What term describes this type of adaptation?
Adaptation that increases the number of cells within a tissue is known as hyperplasia. This is in contrast to hypertrophy, in which the cells increase not in number but in size.
139
During bowel transplantation, which branch(es) of the aorta must be identified and anastomosed to supply blood to the jejunum, ileum, and ascending colon?
1. The superior mesenteric artery supplies blood to the intestine from the proximal jejunum to the proximal transverse colon.
2. The celiac trunk supplies the stomach, liver, spleen, and duodenum.
3. The inferior mesenteric artery supplies the distal transverse colon, descending colon, and sigmoid
colon.
140
How might octreotide be used in this patient?
As a somatostatin analog, octreotide inhibits the release of gastrin. This reduces gastric secretions that would otherwise be in excess compared to the length of bowel and further impede absorption.
141
How does malabsorption of bile salts affect prothrombin time (PT) and partial thromboplastin time (PTT)?
Malabsorption of bile salts leads to an inability to properly absorb fat and fat-soluble vitamins (ADEK). PT and PTT both increase secondary to a lack of vitamin K, which is a necessary cofactor in the γ-carboxylation of multiple clotting factor glutamate residues.
142
What is the most likely diagnosis?
Gastric cancer. Because of symptoms similar to peptic ulcer disease and gastritis, gastric cancer is frequently misdiagnosed. Hence, patients are typically diagnosed at a late stage and prognosis is therefore poor (5% survival at 5 years).
143
What 7 risk factors are associated with gastric cancer?
1. Infection with Helicobacter pylori.
2. Chronic gastritis.
3. Smoking.
4. Diets high in nitrosamines (ie, smoked, cured, or pickled foods) commonly found in East Asia, the Andes, Scandinavia, and eastern Europe.
5. Pernicious anemia and type A blood (associated with gastritis).
6. Family history.
7. Previous gastric surgery.
144
What will the biopsy findings reveal?
Adenocarcinoma is the most common type of gastric cancer, and its hallmark is signet-ring cells on histopathology (Figure 7-14). Other signs include linitis plastica, or “leather-bottle stomach,” which is a diffusely infiltrative cancer and portends a worse prognosis. It is also important to rule out gastric lymphoma, which is frequently associated with H pylori and may regress without surgery if the bacteria can be eradicated.
145
How does gastric cancer spread?
Gastric cancer metastasizes by direct extension through the gastric wall and the lymphatic system and via peritoneal spread.
146
Why can patient's with gastric cancer suffer from dyspareunia and dyschezia?
These symptoms result from metastasis via peritoneal spread to the pouch of Douglas (the rectouterine cul-de-sac). This may be felt on rectal examination as an anterior rectal wall mass or a “Blumer shelf.” Gastric carcinoma metastasis to the ovary is called a Krukenberg tumor.
147
What is a Virchow node?
A Virchow node is an enlarged left supraclavicular lymph node. If it is found on physical examination, likelihood of metastatic disease is increased. Additional signs of lymphatic metastasis include a Sister Mary Joseph node (periumbilical nodule) and an Irish node (left axillary node).
148
What is the most likely diagnosis, and what are the potential causes of this condition in this patient?
149
What anatomic structure distinguishes an upper GI bleed from a lower GI bleed?
The ligament of Treitz marks the junction between the duodenum and the jejunum. Bleeding proximal to the ligament of Treitz is defined as an upper GI bleed.
150
If the patient was previously diagnosed with esophageal varices, what medication may have been prescribed to prevent an upper GI bleed?
Nonselective β-blockers such as propranolol reduce blood flow in the portal system by creating unopposed α-adrenergic vasoconstriction of the mesenteric vessels. Because of the side effect of bronchoconstriction, patients with asthma, chronic obstructive pulmonary disease, and other pulmonary conditions must be carefully evaluated before use.
151
What is the appropriate management for Esophagogastric varices rupture?
In cases of massive hematemesis, the first goal is intravenous fluid resuscitation and stabilization. Nasogastric tube lavage is indicated to prevent aspiration. It is also used to distinguish between upper and lower sources of GI bleeding and to identify high-risk lesions as sources of bleeding. Depending on the patient’s condition, the next step could be either a diagnostic or therapeutic endoscopy.
152
What is the most likely diagnosis?
Vitamin B12 deficiency.
153
What are the functions of the vitamin implicated in this condition, and how does its deficiency result in this presentation?
Vitamin B12 is a cofactor for methionine synthase, which catalyzes the transfer of a methyl group from N-methyltetrahydrofolate to homocysteine, producing tetrahydrofolate (TH4) and methionine. Decreased production of TH4 interferes with DNA synthesis required for hematopoiesis (Figure 7-15A), resulting in megaloblastic anemia. Vitamin B12 is also a cofactor for methylmalonyl CoA mutase (Figure 7-15B), an enzyme involved in the catabolism of odd-numbered fatty acid chains.
154
What are the possible causes of Vitamin B12 deficiency
The most common cause of vitamin B12 deficiency is pernicious anemia, an autoimmune disorder in which intrinsic factor–producing gastric parietal cells are destroyed. Intrinsic factor is necessary for vitamin B12 absorption.
Other causes include malabsorption (eg, celiac sprue, enteritis, or Diphyllobothrium latum infection) and absence of the terminal ileum (as in Crohn disease or surgical resection). Vitamin B12 deficiency is rarely due to insufficient dietary intake. However, after several years, strict vegetarians are at risk, because the nutrient is found only in animal products.
155
For what other condition are patient's with Vitamin B12 deficiency at risk for?
B12 deficiency leads to subacute combined degeneration of the spinal cord, mostly affecting the posterior columns. Neurologic problems often manifest as paresthesias and ataxia. Over time, symptoms such as spasticity and paraplegia can develop. The exact role of vitamin B12 deficiency in this pathology is unclear. Neurologic symptoms are often irreversible.
156
What vitamin deficiencies can cause megaloblastic anemia?
1. Vitamin B12 deficiency.
2. Folic acid deficiency. Although there is an elevated level of serum homocysteine as in vitamin B12 deficiency, accumulation of methylmalonic acid (Figure 7-15) and neurologic symptoms are not associated with folic acid deficiency.
157
What is the most likely diagnosis?
A history of recurrent peptic ulcers suggests Zollinger-Ellison (ZE) syndrome, in which there is hypersecretion of gastrin from a gastrinoma, resulting in high gastric acid output.
158
What are 3 common risk factors for peptic ulcer disease?
1. Helicobacter pylori infection.
2. Nonsteroidal anti-inflammatory drugs.
3. Smoking.
159
With what endocrine disorder is Zollinger-Ellison (ZE) syndrome associated?
Approximately 20% of patients with ZE syndrome also have multiple endocrine neoplasia type I (Wermer syndrome). Such patients will also have parathyroid adenomas, resulting in hyperparathyroidism, and/or anterior pituitary tumors.
160
How is secretion of gastric acid normally regulated?
Gastric acid is secreted by parietal cells of the stomach in response to gastrin, acetylcholine (vagal input), and histamine (Figure 7-16). Acid secretion is inhibited by somatostatin.
161
What is the pathophysiology of this patient’s diarrhea?
The voluminous acid secretion overwhelms the buffering capacity of pancreatic bicarbonate. Thus, pancreatic enzymes are inactivated in this acidic environment, impeding digestion. Excess acid also interferes with the emulsification of fats, leading to steatorrhea.
162
What are the appropriate treatments for Zollinger-Ellison (ZE) syndrome?
Surgical treatment involves resection of the gastrinoma (typically at the head of pancreas). Medical treatment uses proton pump inhibitors to suppress gastric acid secretion.
