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Flashcards in Small Bowel - Shelf-Life Deck (19):

A 45 year old man with a recent history of bowel surgery presents with abdominal pain, nausea, vomiting and failure to have a bowel movement for the last several days. He describes the pain as intermittent. He had diarrhea at first but is now complaining of constipation. He is afebrile. His pulse is 95 beats per minute and respiratory rate of 17 breaths per minute. His lab studies show a mild elevation in leukocytes with a left shift and an elevated blood urea nitrogen. The remainder of his lab results are unremarkable. Plain radiography is conducted. Which of the following is the next best step in management? 

A. Abdominal CT 

B. Intravenous hydration, nasogastric suction and antibiotics

C. Immediate laproscopy

D. Morphine sulfate

E. Promethazine

B. IV hydration, nasogastric suction and antibiotics

  • This patient is most likely suffering from a small bowel obstruction. 
  • Initial management should always include aggressive fluid resuscitation, bowel decompression and antibiotics (with coverage of gram-negative and anaerobic organisms), analgesics and antiemetics. 
  • KUB can reveal multiple large dilated loops of small bowel with air-fluid lvels. 
  • A nonoperative trial is indicated in all cases of suspected partial or simple bowel obstruction. 
  • If complete small bowel obstruction is present or evidence of stragulation, srugical care with laparoscopy is indicated. 

Why are other answers wrong? 

  • Although abdominal CT scans are useful with the diagnosis of strangulated obstructions and working out the etiology of small bowel obstruction, this patient already has sufficient evidence for diagnosis and a clear etiology
  • An abdominal CT would be costly and uncessary at this point
  • Immediate laparoscopy would be required if there was evidence of strangulation or complete obstruction. 
  • Morphine sulfate would be indicated to assist pain
  • However, IV hydration is always the first step
  • Promethazine is useful as an antiemetic for small bowel obstruction and may be indicated. 
  • However, IV hydration should always be the initial step. 


A 67 year old man presents with vague abdominal discomfort, weight loss and intermittent nausea that has been increasing over the last 6 months. He has a history of smoking but does not drink alcohol. His temperature is 36.7C, BP - 130/80, pulse 80, RR - 14. Physical examination is unremarkable. Heme positive stool. Hemoglobin of 10.5. Colonoscopy unremarkable but upper endoscopy showed an annular mass in the duodenum. Which of the following is the most likely diagnosis? 

A. Adenocarcinoma

B. Carcinoid Tumour

C. Lymphoma

D. Sarcoma

E. Squamous cell carcinoma

A. Adenocarcinoma 

  • This patient has symptoms and diagnostic tests suggestive of a neoplasm. 
  • Small bowel tumours are exceedingly rare accounting for approximaltey 1% of gastrointestinal carcinomas. 
  • The most common neoplasm of the small bowel is metastatic. 
  • However, the most common primary tumour is adenocarcinoma.
  • Adenocarcinomas are most common in the duodenum region in the ampulla of Vater. 
  • Tumours are usually annular or polypoid. 
  • Mucosal ulceration may be present

Why are other answers wrong? 

  • Caricinoid tumours develop from enterochromograffin cells and are most common in the appendix. 
  • The small bowel is the second most common location and usually occurs in the distal ileum.
  • They begin as polypoid masses and may invade through the wall of the small bowel. 
  • Symptoms may initial occur from small bowel obstruction. 
  • Some tumours may secrete serotonin and other vasodilator substances which results in malignant carcinoid syndrome with irritable syndromes, diarrhea, bronchoconstriction and flushing. 
  • Lymphomas have a variety of morphologies and accout for approximately 15% of small bowel cancers. 
  • Sarcomas present most commonly with acute gastrointestinal bleeding. 
  • Squamous cell carcinoma is extremely rare in the small bowel 


A 1 year old boy presents with chronic diarrhea, failure to thrive, poor growth and difficulty feeding. Celiac disease along with several other conditions is suggested in the initial differential diagnosis. Which of the following antibodies are associated with a diagnosis of celiac disease? 

A. Anti-dsDNA

B. Antiendomysial and antigliaden

C. Antimitochondrial and antigliaden

D. Anti-SRP and antitransglutaminase

E. Antitopisomerase antibodies

B. Antiendomysial and antigliaden

  • Celiac disease is a multifactorial autoimmune disease that primarily affects the small intestine. 
  • It is characterised by progressive atrophy and flattening of the small intestinal mucosa. 
  • In the pediatric population, symptoms often present before age 2. 
  • GI symptoms are very common and usually appear between 9 months and 24 months of age (when gluten is typically introduced into the diet) 
  • Chronic diarrhea, anorexia, abdominal distention and/or pain, poor growth, failure to thrive and severe malnutrtion may occur. 
  • Diagnosis can be made usuing several modalities including serum antibodies to the IgA endomysium and IgA tissue transglutaminase. 
  • These antibodies are highily sensitive and specific. 

Why are other answers wrong? 

  • Anti-dsDNA antibodies are found in patients with SLE.
  • While antigliaden antibodies are found in patients with celica disease, antimitochondrial antibodies are associated with primary biliary cirrhosis. 
  • Although antitransglutaminase antibodies are associated with celiac disease, anti-SRP antibodies are associated with inflammatory myopathies. 
  • Antitopisomerase anitbodies are associated with scleroderma. 


A 42 year old man is brought to the emergency department after a motor vehicle accident. He has multuiple major injuries and is immediately brought into the operating room. During the surgery, it is found that a distal segment of the small bowel is injured and it is subsequently removed. Which of the following arteries most likely supply this segment of bowel? 

A. Celiac artery and superior mesenteric arteries

B. Inferior mesenteric artery and superior mesenteric arteries

C. Middle and right colic arteries

D. Pancreaticoduodenal and superior mesenteric arteries

E. Superior mesenteric artery and left colic artery 

B. Inferior mesenteric artery and superior mesenteric arteries 

  • The blood supply to the majority of the small bowel is through the superior mesenteric artery. 
  • The proximal small bowel is supplied by branches of the celiac artery
  • The very distal part of the small bowel does receive some collateral flow from the iliocolic artery, which is a branch of the inferior mesenteric artery. 

Why are other answers wrong? 

  • Although branches of the superior mesenteric artery do supply the distal small bowel, the celiac artery does not. 
  • Although the right colic artery does supply some blood to the distal small bowel ,the middle colic primarily supplies the transverse colon and does not supply blood to the small bowel. 
  • Although the superior mesenteric artery does supply the majority of the small bowel, the pancreaticoduodenal arteries (superior and inferior) supply blood to the duodenum an pancreas. 
  • Although the superior mesenteric artery does supply blood to the small bowel, the left colic artery supplies the transverse and descending colon. 


A 12 year old boy presents with a small bowel obstruction several years after surgery for an appendectomy. During the exploratory laparotomy, several large lymph nodes are found in the paracaval and aortic area. Several of the nodes are removed and sent for pathologic diagnosis. Histology reveals sheets of small round and homogenous lymphocytes and a ''starry sky'' apperance. The tumour cells stain positive for CD19 and CD20 and strongly positive for Ki67. Which of the following is the most likely reason for the patient's small bowel obstruction? 

A. Acute myeloid leukemia

B. Burkitt lymphoma

C. Hodgkin lymphoma 

D. Lymphoid hyperplasia 

E. Previous surgery

B. Burkitt lymphoma 

  • This patient's history and biopsy results are consistent with a small bowel obstruction secondary to Burkitt lymphoma. 
  • The histologic description of the Burkitt lymphoma is characterised by uniform and round cells with course chromatin, a thin rim of cytoplasm, very high mitotic rate (Ki67 is virtually 100% positive), diffuse growth pattern and B-cell lineage (CD19 and CD20). 
  • It is often described as a ''starry sky'' apperance. 
  • The small intestine is a common site of Burkitt lymphoma in children and young adults. 
  • They may present with signs of small bowel obstruction due to the mass effect of the lymph nodes. 
  • Treatment consists of chemotherapy - may include rituximab (a monoclonal antibody against CD20). 

Why are other answers wrong? 

  • While there are cases of small bowel obstruction in acute myeolid leukaemia - the histologic appearance of the tumour above is not consistent with this diagnosis. 
  • Hodgkin lymphoma may occur in the small bowel and cause symptoms of small bowel obstruction. The histologic description above is not that of Hodgkin lymphoma. 
  • Lymphoid hyperplasia may cause small bowel obstruction and can occur in a variety of conditions including in reaction to a GI infection. 
    • Histology will show reactive lymphoid tissue rather than neoplastic changes. 
  • While previous surgery is a common cause of small bowel obstruction in the general population, lymphatic obstruction from mass effect in the retroperitoneum is the likely cause in this patient. 


A 2 year old boy presents with intermittent abdominal pain and crying. The mother reports the child has also been having sticky red stools with mucus and occasional vomiting. The child is afebrile. On examination, the pain is diffuse and there is a palpable ''sausage'' shaped mass in the lower right quadrant. Which of the following is the next best step in management? 

A. Abdominal CT scan

B. Abdominal radiograph

C. Appendectomy 

D. Contrast enema

E. Laparotomy 


D. Contrast enema 

  • This child is most likely suffering from intussusception. 
  • The peak age group for intussusception is 5-10 months, although it may occur later in life as well. 
  • The usual presentation is a child with intermittent abdominal pain, vomiting and stools with blood and mucus often described as ''current jelly stools''. 
  • The condition is a medical emergency and should be treated as soon as possible. 
  • The initial management involves a contrast enema, which is both diagnostic and may be therapeutic in most cases. 
  • If reduction with contrast fails, surgery is indicated. 

Why are other answers wrong? 

  • Although an abdominal CT scan can easily diagnose an intussusception, they are costly and involve unnecessary doses of radiation. 
  • If imaging is neeed, abdominal ultrasonography is the imaging modality of choice. 
  • Although abdominal radiographs are inexpensive and fast - they have poor sensitivity for intussusception. 
  • However, abdominal radiography may be useful for ruling out causes of abdominal pain including constipation and free-pertioneal air. 
  • This patient's symptoms are not consistent with appendecitis - thus an appendectomy is not indicated. 
  • If a contrast enema fails to correct the problem - laparotomy may be indicated as the next step. 


A 68 year old man with a history of diabetes mellitus and CAD presents with weight loss and worsening constipation over the last 6 months. Suffers from nausea and abdominal cramping. Has 30 year history of smoking - drink three bears daily. Is on metformin, aspirin, simvastatin, nitroglycerin and metoprolol. On examination, his abdomen is distended and tympanic. A recent colonscopy performed several months ago was unremarkable. Which of the following is the next best step in management? 

A. Capsule endoscopy 

B. Decrease dose of aspirin 

C. Decrease dose of metformin 

D. Discontinue nitroglycerin 

E. Upper GI series with small bowel follow throughs 

E - Upper GI series with small bowel follow through 

  • This patient's worrying symptoms of weight loss and constipation along with his history of smoking are concerning for cancer or potentially serious disease involving the bowel. 
  • This patient will need a workup for malignany including an upper gastrointestinal series. 
  • Upper GI series with small bowel follow through will show abnormalities in 53 - 83% of patients and is well established as a useful imaging modality in patients with suspected small bowel malignany. 

Why are other answers wrong? 

  • While capsule endoscopy may eventually be needed if other tests fail to identify the source of this patient's symptoms, it would not be the next best step. 
  • Although aspirin and other NSAIDs may cause bowel discomfort it would not explain this patient's symptoms
  • Although GI complaints are commonly associated with metformin they would not explain this patient's weight loss and other complaints. 
  • Other than rare nausea, nitroglycerin is not associated with GI symptoms. 


A 33 year old man with an unremarkable medical history complains of bloating, watery diarrhea, floating stools, poor appetite and fatigue. On examination he appears pale. The remainder of the examination is unremarkable. Lab studies reveal a macrocytic anaemia with normal folate levels. The patient's stool has an elevated pH and D-lactic acid levels. A breath test reveals an early rise in hydrogen after ingestion of 14C glycoholic acid. Which of the following is the most likely diagnosis? 

A Bacterial overgrowth

B Celiac disease

C Cystic fibrosis 

D Irritable bowel syndrome 

E Short bowel syndrome 

A - Bacterial Overgrowth 

  • This patient is most likely suffering from bacterial overgrowth syndrome. 
  • Signs and symptoms include watery diarrhea, steatorrhea, bloating, abdominal pain, diarrrhe, dyspepsia and weight loss
  • Other symptoms may occur as a result of vitamin deficiencies including anaemia from vitamin B12 deficiency. 
  • This patient's macrocytic anaemia is most likely due to this deficiency. 
  • The typical work up for bacterial overgrowth syndrome includes:
    • Eliminating causes of:
      • Diarrhea
      • Anaemia 
      • Malabsorption
  • In bacterial overgrowth, the stool is often acidic. 
  • D-lactic acidosis may occur and can be measured to help distinguish bacterial overgrowth from other causes of similar symptoms
  • Treatment includes:
    • antibiotics 
    • nutritional support aimed at rebalancing the gut's natural flora 
  • Tetracycline is the most common antibiotic used for this purpose. 

Why are other answers wrong? 

  • Celiac disease may present with similar symptoms as above and may also include steatorrhea and vitamin deficiences. 
  • The diagnosis is usually made with biopsy and seurm antibody studies
  • The patient's symptoms are not consistent with celiac disease 
  • Cystic firbosis may appear with similar symptoms but most likely present at a much earlier age. 
  • Short bowel syndrome can present in a similar manner but patients usually have a history of Crohn disease, tumours or previous bowel surgeries. 


A 65 yeaar old man with a history of Crohn's disease and multiple bowel surgeries presents with fatigue, nausea and diarrhea and abdominal cramping. On examination he appears pale. There is stomatitis and glossitis apparent on a head and neck examination. Lab studies reveal iron deficiency anaemia. His serum albumin is 2.1. A C-reative protein assay and ESR are normal. Which of the following is the most likely diagnosis? 

A. Active Crohn disease 

B. Anoreix nervosa

C. Celiac disease

D. Short bowel syndrome 

E. Small bowel malignancy

D- Short Bowel Syndrome 

  • This patient is most likely suffering from short bowel syndrome.
  • This may occur after multiple bowel surgeries and resections 
  • AS the average small intestinal length is approximately 600 cm studies have shown that any disease which results in less than 200 cm of viable small bowel may result in short bowel syndrome. 
  • This condition is common in patients with CD and a history of multiple bowel resections. 
  • Symptoms and clinical signs are often associated with malnutrition and may include vitamin deficiences, fatty acid deficiencies and mineral deficiencies. 

Why are other answers wrong? 

  • Although this patient may have CD it would usually be accompanied by an elevated ESR or CRP
  • Active CD is often accompanied by rashes and joint pains.
  • Although anorexia nervosa may present with malnutrition, it is almost exclusively found in younger and usually female patients. 
  • Additionally these patients usually do not have a history of multiple bowel surgeries
  • Celiac disease may present similarly to short bowel syndrome including malnutrition
  • However dermatitis herpetiformes is the associated skin finding. 
  • Symptoms are usually associated with a gluten diet and occur in younger patients. 
  • Patietns may have positive antitransglutaminase antibodies
  • Small bowel malignancies may often present with similar symptoms. 
  • However, in this patient with a history of multiple small bowel surgeries - short bowel syndrome is much more likely. 


A 31 year old woman presents with abdominal pain that has occurred over the last year. She recalls that she often will have diarrhea and constipation within the same week. She has a history of depression. Her temperature is 37.1, blood pressure is 120/82 mmHg, pulse 70 bpm and respirations 12/min. After a thorough workup, she is diagnosed with irritable bowel syndrome. Which of the following symptoms is least associated with irritable bowel syndrome?

A. Back pain 

B. Bloating

C. Headache. 

D. Sensation of incomplete stool evacuation 

E. Weight loss 

E. Weight Loss 

  • Irritable bowel syndrome is a clinical based diagnosis of chronic bowel discomfort. 
  • Patients often complain of abdominal pain with frequent episodes of diarrhea, constipation or both. 
  • Feeling of incomplete evacuation of stool is common as well as other chronic disorders such as:
    • Fibromyalgia
    • Depression
    • Headaches
    • Backaches
    • Other psychiatric disorders
  • The diagnosis that can be made based on symptoms along with absence of certain worrying characteristics such as age greater than 50, gross blood in the stool, signs of infection, family history of bowel disease and weight loss. 

Why are other answers wrong? 

  • Back pain is a common complaint in patients with irritable bowel syndrome
  • Bloating and abdominal distention are a common complaint of patients with irritable bowel syndrome
  • Headache and other chronic fatigue like symptoms are associated with irritable bowel syndrome. 
  • One of the most common symptoms of IBS is the sensation of incomplete bowel evacuation. 


A 62 year old man presents with a history of coronary artery disease presents with weight loss, nausea, vomiting and abdominal pain that starts after eating. He reports that these symptoms have been very stressful for him and more recently he has been fearful of eating due to the pain. On the abdominal examination there is no rebound or guarding. Splanchnic angiography reveals narrowing of superior mesenteric artery. Which of the following is the best treatment for this man's condition? 

A. Bowel resection 

B. Limit eating ot small meals low in fat content

C. Long term warfarin therapy 

D. Observation, regular exercise and lifestyle changes 

E. Transaortic endarterectomy 

E. Transaortic endarterectomy 

  • Chronic mesenteric ischaemia is a condition caused by atheroslcerosis of the mesenteric arteries (most commonly the superior mesenteric artery) and is characterised by the triad of:
    • Postprandial abdominal pain 
    • Food avoidance
    • Weight loss 
  • The symptoms are caused by a gradual reduction in blood flow to the intestines. 
  • Since blood flow increases significantly during meals, symptoms may often present postprandial. 
  • It occurs most commonly in older patients with known atherosclerotic disease. 
  • Treatment includes surgical revascularization or stenting the involved artery. 
  • Transaortic endarterectomy is one surgical approach that is often utilised in cases of superior mesenteric artery narrowing.

Why are other answers wrong? 

  • Bowel resection may be needed in advanced causes of acute mesenteric ischaemia, but is typically not performed unless the bowel becomes necrotic. 
  • Although eating small meals and food low in fat content may be utilised in the treatment of chronic mesenteric ischaemia - surgical management is the definitive treatment. 
  • Medical management with long term warfarin therapy is sometimes used in poor surgical candidates and patients who are not candidates for stenting. 
  • Although regular exercise and lifestyle changes are important in the management of chronic mesenteric ischaemia, observation in this patient would not be appropriate. 


A 2 week old neonate is brought into the emergency department with irritability and bilious vomiting. The infant was born at 39 weeks via vaginal birth without complications. He is afebrile and vital signs are within normal limits. On examination, the abdomen is distended and diffusely tender to palpation. There is hyperresonance with percussion. Upper GI series is conducted. Which of the following is the most likely diagnosis? 

A. Duodenal atresia

B. Intussusception 

C. Necrotizing ileus 

D. Small bowel obstruction 

E. Volvulus 

E. Volvulus 

  • This neonate is most likely suffering from a midgut volvulus. 
  • A volvulus is characterized by rotation of the gut around its mesentery, which results in compromised blood flow. 
  • Volvulus is a surgical emergency and should be excluded in any infant presenting with bilious vomiting. 
  • In infants it is often due to congenital malrotation of the gut. 
  • The imaging study shows malrotation, midgut volvulus and duodenal obstruction. 
  • Treatment includes insertion of a nasogastric tube, intravenous hydration and antibiotics. 
  • Diagnosis may be established with an upper gastrointestinal series with barium contrast. 
  • Imaging will sometimes show a ''spiral'' or ''cork-screw'' tapering of contrast and an abnormal location of the superioer mesenteric vessels. 

Why are other answers wrong? 

  • Duodenal atresia occurs in association with Down syndrome and often occurs a few hours after birth with bilious vomiting. 
  • Abdominal distention is absent
  • Imaging will often show the classic ''double bubble' sign. 
  • Treatment is surgical 
  • Intussusception is characterised by intermittent abdominal pain with vomiting and stools with blood and mucus. 
  • Stools are often described as ''current jelly'' in apperance. 
  • The condition is a medical emergency and should be treated as soon as possible. 
  • The initial treatment is a contast enema, which is both diagnostic and may be therapeutic in most cases
  • If reduction with contrast fails, surgery is indicated. 
  • Necrotizing ileus usually occurs 10 to 12 days after birth with distention, vomiting and bloody stools.
  • On examination, the abdomen will often be distended. 
  • Initial treatment involves nasogastric suction, IV support and nutrition, and antibiotics. 
  • If a trial of medical therapy fails, then surgical management is required. 
  • Small bowel obstruction may also be characterized by abdominal distention. 
  • However, this patient's imaging is more characteristic of a volvulus. 


A 4 year old girl presents with bloody stools. She denies abdominal pain, fever, vomiting or other symptoms. Her vitals are within normal limits. On examination, she appears happy and playful, but slightly pale. The remainder of the physical examination is unremarkable. Lab studies show a hemoglobin level of 8.5. Which of the following tests will most likely reveal the diagnosis? 

A. Abdominal CT scan

B. Arteriography 

C. Barium contrast study 

D. Plain radiography 

E. Technetium 99m pertechnetate scintiscan



E. Technetium-99m pertechnetate scintiscan. 

  • Meckel diverticulum is the most common congenital malformation of the small intestine. 
  • It is caused by oblieration of the vitelline duct. 
  • It most commonly presents as asymptomatic rectal bleeding in a child. 
  • However, other symptomatic presentations do occasionally occur including:
    • Haemorrhagic shock 
    • Peritonitis 
    • Intestinal obstruction 
    • Acute inflammation of the diverticulum 
  • The imaging modality of choice is a Meckel scan using technetium-99m. 
  • The preterchnetate is take up by the gastric mucosa in the Meckel diverticulum gastric mucosa and may be detected on imaging.

Why are other answers wrong? 

  • Abdominal CT scanning is typically not helpful in the diagnosis of Meckel diverticulum because distinguishing the diverticulum from separate loops of bowel is extremely difficult. 
  • Selective arteriography may sometimes be helpful when scintography and barium studies are negative, but are usually only helpful when bleeding is greater than 1 mL/min. 
  • Barium contrast studies are usually reliable in detecting a Meckel diverticulum but may sometimes reveal a blind ending pouch in the distal ileum. 
  • Plain radiography is of limited value and is usually normal. 
  • Subtle signs evident on plain radiography may include signs of intestinal obstruction or perforation which are uncommon complications of Meckel diverticulum. 


A 33 year old man with a history of psoriatic arthritis presents with abdominal pain, diarrhea,fever and weight loss over the last 6 months. He reports that the abdominal pain is often relieved by defecation. He is currently afebrile and his other vital signs are within normal limits. On examination, there are several ulcers visible on his oral mucosa. Which of the following is not a typical characteristic of this patient's disease? 

A. Caseating granulmoas on biopsy 

B. Cobblestone appearance

C. Involvement of the ascending colon 

D. Involvement of the small bowel 

E. Transmural inflammation on biospy 

A. Caseating granulmoas on biopsy. 

  • This patient is presenting with signs and symptoms of Crohn disease, a form of inflammatory bowel disease that can affect any part of the gastrointestinal tract from mouth to anus. 
  • There are numerous manifestations of Crohn disease that may include gastrointestinal in nature and extraintestinal. 
  • Biopsy with histologic examination is important for confirming the diagnosis. 
  • Histology reveals transmural chronic inflamation and noncaseating granulomas. 
  • There may also be mucosal fragments and patchy ulcerations/erosions suggesting 'skip lesions'. 
  • Caseating granulomas are not a feature of Crohn disease and are more suggestive of tuberculosis. 

Why are other answers wrong? 

  • On endoscopy, the intestinal mucosa of Crohn disease patients is often described as appearing like a 'cobblestone street' with areas of ulceration separated by areas of healthy tissue. 
  • Crohn disease may involve the full length of the bowel including the ascending colon. 
  • The terminal ileum is the most common segment of small bowel involved in Crohn disease
  • Transmural inflammation is a characteristic of Crohn disease. In ulcerative colitis, the inflammation is limited to the mucosa. 


An 82 year old woman nursing home resident presents with worsening abdominal distention and crampy abdominal pain. Her medical history includes her current diagnosis of Alzehimer disease and arthritis. Her past surgical history is remarkable for a hysterectomy at age 45, cholecystectomy at age 39 and appendectomy at age 16. Workup reveals a small bowel obstruction. Which of the following is not a mechanical cause of small bowel obstruction? 

A. Abdominal adhesions

B. Cancer

C. Hernia

D. Inflammatory bowel disease 

E. Narcotic medications 

E. Narcotic medications 

  • There are many potential causes of small bowel obstruction that are both mechanical and paralytic in nature
  • This patient has had multiple past abdominal surgeries suggesting abdominal adhesions as a potential mechanical cause of her symptoms. 
  • Other mechanical cause of small bowel obstruction include but are not limited to:
    • Hernias 
    • Gallstones
    • IBD
    • Tumours
    • Congenital malformations
    • Volvulus 
    • Foriegn bodies 
  • Paralytic causes include:
    • Medications (opiods and other narcotics) 
    • Mucosal infections
    • Intestinal ischaemia 
    • Surgery 
    • Kidney diseae
    • Long standing diabetes

Why are other answers wrongs? 

  • Abdominal adhesions are the most common mechanical cause of small bowel obstruction 
  • Cancer may grow to occlude the small bowel lumen or push on the small bowel to cause obstruction 
  • Hernias may cause mechanical partial or complete bowel obstruction 
  • Small bowel obstruction is a common complication of Crohn disease 



A 45 year old man with a history of severe Crohn disease undergoes an operation with removal of a segment of diseased small bowel. During the surgery, the distal small bowel is found to be severely involved and is subsequently removed. Which of the following is not a potential problem associated with removal of the distal small bowel? 

A. Bile salt recycling 

B. Decreased water and electrolyte reabsorption 

C. Fat malabsoprtion 

D. Water-soluble vitamin deficiencies 

E. Vitamin B12 deficiency 

D. Water-soluble vitamin deficiencies 

  • The distal small bowel has a variety of functions and includes some specific to the terminal ileum. 
  • Resection of the distal small bowel may therefore result in impaired water and electroylte absorption, bile salt enterohepatic recycling (resulting in fat malabsorption if stores are depleted enough) and vitamin B12 absoprtion. 
  • Water soluble vitamins are primarily absorbed in the proximal small bowel and will thus not usually be affected by distal small bowel resection. 

Why are other answers wrong? 

  • Bile salt recycling is a primary function of the terminal ileum. 
  • If the impairment is severe enough, bile acids may be depleted in the body resulting in fat malabsorption. 
  • Resection of the distal ileum may severely impair water and electrolyte reabsorption. 
  • Resection of the distal ileum may severely impair water and electrolyte reabsoprtion
  • Fat malabsorption may occur secondary to bile salt depletion with terminal ileum resection 
  • Vitamin B12 deficiency may occur when greater than 60cm of the distal small bowel is resected .


A 35 year old man with a history of Crohn disease undergoes bowel resection following an acute flare up of his disease. The surgeon removes a 3 cm portion of the ileum and sends the specimen for pathologic evaluation. Which of the following describes the layers of the small bowel from inside to out that may be observed with histologic evaluation? 

A. Mucosa, circular muscle layer, submucosa, muscularis mucosa, longitudinal muscle layer, serosa.

B. Mucosa, muscularis mucosa, submucosa, circular muscle layer, longtiduinal muscle layer, serosa 

C. Mucosa, muscularis mucosa, submucosa, longitudinal muscle layer, circular muscle layer, serosa 

D. Mucosa, submucosa, muscularis mucosa, circular muscle layer, longitudinal muscle layer, serosa

E. Mucosa, submucosa, muscularis mucosa, longitudinal muscle layer, circular muscle layer, serosa 

B - Mucosa, muscularis mucosa, submucosa, circular muscle layer, longitudinal muscle layer, longitudinal muscle layer, serosa 

  • The layers of the intestinal wall from inside to out are mucosa, muscularis mucosa, submucosa, circular muscle layer, longitudinal muscle layer and serosa. 
  • The mucosa contains villi which are important for food absoprtion
  • Between the circular muscle layer and longitudinal muscle layer is the myenteric pleus. 


A 23 year old man presents repeated episodes of abdominal pain that he has not been able to explain. On examination, there are multiple small, brown and flat freckles around and inside the patient's mouth. After a thorough workup, the patient is found to have intussusception. Which of the following is not a characteristic of this patient's underlying disease? 

A. Autosomal dominant inheritance

B. Increased risk of intestinal malignancy

C. Lymphoid hyperplasia 

D. Multiple gastrointestinal hamartomas 

E. STK11/LKB1 mutation 

C. Lymphoid hyperplasia 

  • Peutz-Jeghers syndrome is a rare autosomal dominant condition characterized by the development of multiple hamartomatous polyps throughout the gastrointestinal tract and hyperpigmented macules on the lips and oral mucosa. 
  • Other problems associated with Peutz-Jeghers syndrome include:
    • bleeding and prolpase from the rectum 
    • menstrual irregularities 
    • gynecomastia in men 
    • precocious puberty 
    • hematemesis 
    • weakness due to anaemia 
  • Lymphoid hyperplasia is not a feature of PJ syndrome. 
  • Due to increased incidence in a variety of cancers, patients with PJ syndrome require close surveillance including:
    • esophogogastroduodenoscopy and colonscopy ever 2 years for gastrointestinal cancer 
    • imaging of the pancreas yearly for pancreatic cancer 
    • ultrasounds of the pelvis (women) or testicles (men) yearly for ovary and testicular cancer
    • mammography for breast cancer
    • pap smears for cervical cancer

Why are other answers wrong? 

  • Peutz Jeghers syndrome is indeed inherited in an autosomal dominant fashion. 
  • Patients with Peutz Jeghers syndrome have a 15 fold increase in the incidence of malignany and thus require increased surveillance as described above. 
  • Multiple gastrointestinal hamartomas are a core feature of Peutz-Jeghers syndrome
  • PJ syndrome is caused by a germline mutation in the STK11/LKB1 gene on chromosome 19 (tumour suppressor gene) 


A 13 year old girl presents with nausea, vomiting, diarrhea and fever for the last day. She reports that she ate potato salad the previous day that had been sitting on the counter for several hours. On examination, she appears moderately ill and dehydrates but is able to rehydrate orally. She is diagnosed with bacterial gastritis. Which of the following is not an important mechanism of defense found in the small bowel against invading bacteria? 

A. Gut associated lymphoid tissue 

B. Mucin production 

C. Native bacteria 

D. Paneth cells

E. Tight junctions