MKSAP quiz on gastroenterology

The following cases and commentary, which focus on gastrointestinal problems in hospitalized patients, are excerpted from ACP's Medical Knowledge Self-Assessment Program (MKSAP 15).

Case 1: Massive hematemesis

A 60-year-old man hospitalized for advanced cirrhosis complicated by ascites and encephalopathy is evaluated for massive hematemesis and hypotension. The patient's medications are spironolactone, furosemide, and lactulose.

On physical examination, the temperature is 35.6°C (96°F), the blood pressure is 80/50 mm Hg, the pulse rate is 146/min, and the respiration rate is 20/min. The patient has just vomited red blood and has large-volume ascites; the stool is brown and positive for occult blood. Laboratory studies show hemoglobin of 9 g/dL (90 g/L), platelet count of 60,000/µL (60 × 109/L), and INR of 3.

In addition to rapid volume resuscitation, which of the following is the most appropriate management of this patient?

A. Arteriography
B. Esophagogastroduodenoscopy
C. Intravenous nadolol
D. Mesocaval shunt
E. Transjugular intrahepatic portosystemic shunt

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Case 2: Abdominal pain and elevated enzymes

A 55-year-old woman is evaluated in the hospital for a 2-day history of epigastric abdominal pain, nausea and vomiting, and anorexia. The patient has no significant medical history and takes no medications.

On physical examination, the temperature is 38.0°C (100.5°F), the blood pressure is 124/76 mm Hg, the pulse rate is 99/min, and the respiration rate is 16/min. There is scleral icterus and a slight yellowing of the skin. There is mid-epigastric and right upper quadrant tenderness. There is no palmar erythema, spider angiomata, or other evidence of chronic liver disease.

Laboratory studies show leukocyte count 14,900/µL (14.9 × 109/L), aspartate aminotransferase 656 U/L, alanine aminotransferase 567 U/L, bilirubin (total) 5.6 mg/dL (95.8 µmol/L), amylase 1284 U/L, and lipase 6742 U/L.

Abdominal ultrasonography shows a biliary tree with a dilated common bile duct of 12 mm and cholelithiasis but no choledocholithiasis.

Which of the following is the most appropriate next step in the management of this patient?

A. CT scan of the abdomen and pelvis with pancreatic protocol
B. Endoscopic retrograde cholangiopancreatography
C. Hepatobiliary iminodiacetic acid (HIDA) scan
D. Magnetic resonance cholangiopancreatography

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Case 3: Post-cardiac catheterization

A 74-year-old man is evaluated in the hospital for severe diffuse abdominal pain. He was hospitalized 5 days ago for chest pain and was found to be in rapid atrial fibrillation and a myocardial infarction was diagnosed. He underwent cardiac catheterization and double stent placement after which he has had intermittent hypotension and has remained in atrial fibrillation with a controlled ventricular rate. At the bedside the patient is sweating, nauseated, and holding his abdomen. He cannot respond to questions. His wife says that he has never had any gastrointestinal problems, but that he has not had a bowel movement since he entered the hospital. The patient has chronic atrial fibrillation but he discontinued his anticoagulation therapy 6 months ago; he also has hyperlipidemia. His medications are heparin, metoprolol, simvastatin, clopidogrel, and aspirin.

On physical examination, the temperature is 38.0°C (99.5°F), the blood pressure is 102/60 mm Hg, the pulse rate is 94/min, and the respiration rate is 25/min. There is mild, diffuse abdominal tenderness to palpation without rebound or guarding; there are no palpable abdominal masses. Laboratory studies reveal only a leukocyte count of 13,000/µL (13 × 109/L). Radiograph of abdomen shows no evidence of perforation or obstruction.

Which of the following would be the most appropriate management for this patient?

A. CT arteriography
B. Colonoscopy
C. Intravenous famotidine
D. Lactulose

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Case 4: Bloating after hemicolectomy

A 63-year-old man is evaluated in the hospital 3 days after having undergone a left hemicolectomy for adenocarcinoma of the colon. The patient has bloating and mild diffuse abdominal discomfort. He has not defecated or passed gas since surgery. He is nauseated but has not vomited. His medical history also includes hypertension and type 2 diabetes mellitus, and his medications are oxycodone, lisinopril, and glyburide.

On physical examination, the abdomen is distended with mild diffuse tenderness, tympany, and hypoactive bowel sounds but without rebound or guarding; there are no abdominal masses or organomegaly. Laboratory studies reveal random glucose 290 mg/dL (16.1 mmol/L), potassium 3.1 meq/L (3.1 mmol/L), and magnesium 1.1 mg/dL (0.45 mmol/L); complete blood count, serum thyroid-stimulating hormone, liver chemistry tests, and amylase are normal. Plain radiograph of the abdomen shows diffusely dilated loops of small bowel; CT scan of the abdomen and pelvis also shows dilated loops of bowel without evidence of obstruction.

In addition to glucose control and correction of electrolytes, which of the following is the most appropriate next step in the management of this patient?

A. Insertion of a nasogastric tube to gravity drainage
B. Insertion of a rectal tube
C. Intravenous metoclopramide
D. Minimization of oxycodone

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Case 5: Repeated bloody stools

A 64-year-old woman is evaluated in the emergency department for her second episode of painless bloody stool. Four weeks ago, she was evaluated in the hospital for maroon stool; the hemoglobin at that time was 2 g/dL (20 g/L) lower than previous complete blood counts; esophagogastroduodenoscopy was normal; colonoscopy showed some old blood but no active bleeding. The patient was observed for 2 days and discharged with instructions for outpatient follow-up. Her current episode consisted of two maroon stools, one this morning and one 2 hours ago. Nasogastric lavage yields coffee grounds that clear with 1 L of saline. The patient had a colonoscopy 2 years ago at which time a single adenomatous polyp was detected and removed. She has no personal or family history of bleeding or gastrointestinal malignancy and is otherwise healthy; she has no upper gastrointestinal symptoms, does not use alcohol, and her only medication is a multivitamin.

On physical examination, the temperature is 37.1°C (98.7°F), the blood pressure is 98/62 mm Hg, the pulse rate is 94/min, and the respiration rate is 14/min; the BMI is 23.5. There is no scleral icterus; examinations of the heart and lungs are normal. The abdomen is soft with increased bowel sounds but no hepatosplenomegaly. Rectal examination reveals the presence of maroon and red blood but no palpable masses or hemorrhoids. Laboratory studies reveal hemoglobin of 9.4 g/dL (94 g/L) with a mean corpuscular volume of 86 fL; leukocyte count with differential and platelet count are normal. Prothrombin time, activated partial thromboplastin time, and INR are normal, as are liver chemistry tests. Serum blood urea nitrogen is 34 mg/dL (12.1 mmol/L), and creatinine is normal.

Which of the following is the most appropriate next step in the evaluation of this patient?

A. Colonoscopy
B. Double-balloon enteroscopy
C. Esophagogastroduodenoscopy
D. Technetium red blood cell scan
E. Wireless capsule endoscopy

View correct answer for Case 5

Answers and commentary

Case 1

Correct answer: B. Esophagogastroduodenoscopy.

The first step in the management of acute variceal hemorrhage is the restoration of the intravascular volume using a large bore peripheral intravenous line or a central line. Packed erythrocytes are used as need to replace blood loss and clotting factors are replaced as needed. Platelet transfusions may be indicated if values fall below 50,000/µL (50 × 109/L). In addition, this patient should undergo urgent esophagogastroduodenoscopy and band ligation of esophageal varices. Clinical studies have shown that sclerotherapy was superior to balloon tamponade alone, vasopressin alone, and a combination of vasopressin and balloon tamponade in controlling active variceal hemorrhage, preventing early rebleeding, and improving survival in patients with esophageal and gastroesophageal varices. Band ligation has been shown to be as effective as sclerotherapy for preventing early rebleeding. Therapy should also be started with intravenous octreotide, which reduces portal venous blood inflow through inhibition of the release of vasodilatory hormones and is more effective for controlling bleeding than placebo; however, its ultimate effect on survival is unknown. Bacterial infections are present in a sizable percentage of hospitalized patients with variceal bleeding and are associated with a high mortality rate. Clinical trials have demonstrated that the use of prophylactic antibiotics in these patients results in a reduction in infectious complications and possibly mortality.

Arteriography is not first-line therapy in patients with a variceal bleed from venous portal hypertension. Arteriography is reserved for patients with a presumed arterial source of bleeding as can be seen in peptic ulcer disease or tumors anywhere along the gastrointestinal tract. In such cases, arteriography can be used to identify and embolize the specific vessel involved. This method is usually reserved for cases in which the patient is actively bleeding and either endoscopic therapy has failed to stop the bleeding or the presence of active bleeding interferes with identification of the bleeding site and the patient is unstable. Mesocaval shunt is a surgical shunt that decompresses the portal system by diverting portal venous flow into the inferior vena cava, thus bypassing the liver. This type of shunt is rarely used for acute variceal bleeding as it carries a high intraoperative risk in an acutely decompensated patient with underlying liver disease and coagulopathy.

Intravenous nadolol is not appropriate because this patient is hypotensive and needs endoscopic intervention rather than medical therapy. Lastly, transjugular intrahepatic portosystemic shunting (TIPS) should not be used without first performing an upper endoscopy with esophageal band ligation. Many variceal bleeds can be controlled with endoscopic therapy alone, obviating the need for urgent TIPS which can have significant comorbidities including hepatic decompensation, bleeding complications, or resultant encephalopathy.

Key Point

  • Antibiotics, endoscopic variceal band ligation, and intravenous octreotide are the first-line therapies for acute esophageal variceal bleeding.

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Case 2

Correct answer: B. Endoscopic retrograde cholangiopancreatography.

This patient has a classic presentation of acute pancreatitis with the acute onset of epigastric abdominal pain, nausea, and vomiting associated with markedly elevated pancreatic enzymes. The presence of stones in the gallbladder, a dilated bile duct, and elevated aminotransferase levels highly suggest gallstones as the cause of pancreatitis. The scleral icterus, jaundice, and elevated bilirubin level suggest continuing bile duct obstruction. Abdominal ultrasonography has a sensitivity of only 50% to 75% for choledocholithiasis, and a common duct stone should be suspected in the correct clinical situation even when ultrasonography does not show a stone.

Endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and stone removal is the most appropriate procedure in patients with acute gallstone pancreatitis and with imaging and biochemical evidence of biliary obstruction from a common duct stone. The procedure can document the diagnosis of choledocholithiasis and remove the gallstones, which lessens the morbidity and mortality due to biliary sepsis.

CT scan will likely show evidence of acute pancreatitis and magnetic resonance cholangiopancreatography (MRCP) will show pancreatitis and the presence of a common duct stone, with sensitivities for CT being approximately 75% for stones and MRCP having sensitivities ranging from 80% to 100% as compared with ERCP for the diagnosis of choledocholithiasis. Biliary scintigraphy may show obstruction of the cystic or common bile duct but will not determine the cause. However, CT, biliary scintigraphy, and MRCP will not be therapeutic for bile duct stones.

Key Point

  • In patients with gallstone pancreatitis and evidence of biliary obstruction, endoscopic retrograde cholangiopancreatography and stone removal reduces morbidity and mortality by reducing the risk of biliary sepsis.

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Case 3

Correct answer: A. CT arteriography.

This patient most likely has acute mesenteric ischemia, a potentially fatal condition that typically affects elderly patients. The disorder may result from embolic or thrombotic occlusions of the splanchnic vessels or may be nonocclusive. Superior mesenteric artery embolism is the most common cause, accounting for approximately 50% of cases and usually developing from ventricular or left atrial thrombi in patients with atrial fibrillation. This patient's age, recent myocardial infarction, atrial fibrillation, history of discontinuing anticoagulation, and hypotension are all significant risk factors for this condition. His low-grade fever, hypotension, sudden onset of severe abdominal pain out-of-proportion to physical examination findings, as well as his elevated leukocyte count all support the diagnosis. CT arteriography is a sensitive test for acute mesenteric ischemia; the procedure can evaluate the mesenteric vessels and also assess for signs of bowel ischemia and rule out other potential causes of acute onset abdominal pain, such as perforation or obstruction. Surgical consultation should be done simultaneously because if the results of CT arteriography support the diagnosis of acute mesenteric ischemia, the patient may need emergent surgery. Traditional angiography is the gold standard for diagnosis of acute mesenteric ischemia and can also offer therapeutic options such as the use of vasodilators as well as balloon dilation and stent placement. Surgery is required for patients with peritoneal signs and/or evidence of bowel necrosis on imaging. Surgical interventions include peritoneal lavage, resection of necrotic and perforated bowel, thrombolectomy, patch angioplasty, endarterectomy, and bypass procedures. Successful thrombolytic therapy in stable patients without peritoneal signs has been reported.

Colonoscopy would not be appropriate for this patient, because it does not evaluate the mesenteric vessels or the small intestine, only the mucosa of the colon. Intravenous famotidine therapy for possible dyspepsia would also not be appropriate in this patient with a potentially life-threatening condition. Likewise, although the patient may be somewhat constipated, giving him lactulose only is not correct.

Key Point

  • CT angiography is the most sensitive diagnostic test for acute mesenteric ischemia.

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Case 4

Correct answer: D. Minimization of oxycodone.

This patient has a postoperative ileus. An ileus is a functional, as opposed to mechanical, gut obstruction that occurs when the normal bowel motility is inhibited. Metabolic derangements, medications such as narcotic analgesics and anticholinergic agents, and infection may exacerbate or contribute to the development of an ileus. The pathogenesis of a postoperative ileus likely relates to impaired gut electrical, neurologic, and hormonal activity; inflammatory mediators; and a dysmotility effect from anesthesia. Patients have difficulty tolerating oral intake and may complain of bloating, abdominal pain, and lack of flatus and stool passage; abdominal distention, normal or decreased bowel sounds, and diffuse mild tenderness may be observed on physical examination. An abdominal plain film generally shows air throughout the intestine but may be confused with mechanical small-bowel obstruction because air-fluid levels and minimal colonic gas may also be seen; therefore, CT and barium studies may help distinguish these entities. Management of an ileus is generally supportive, including the discontinuation of any medications such as narcotics and calcium channel blockers that may further slow gut motility and correction of electrolyte and other metabolic abnormalities.

Although nasogastric tubes may be appropriate for a small-bowel obstruction, they are generally not efficacious in managing an ileus except to provide symptomatic relief from emesis. Rectal tubes are used to decompress the colon but would not be helpful in treating an ileus. Studies of metoclopramide therapy in this setting have not shown accelerated postoperative gastrointestinal recovery.

Key Point

  • Ileus is a functional obstruction of the bowel that commonly complicates the postoperative period; treatment is generally supportive, including the discontinuation of medications that slow gut motility and correction of electrolyte abnormalities.

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Case 5

Correct answer: C. Esophagogastroduodenoscopy.

This patient presents with obscure overt bleeding in that blood loss is clinically apparent because of the maroon stool, but the source is not identified despite endoscopic investigation. The most appropriate next test would be to repeat upper endoscopy. Studies have shown that between one third and two thirds of sources of obscure upper gastrointestinal bleeding are found within the reach of the upper endoscope on repeat endoscopy. The missed lesions are most often bleeding erosions associated with hiatus hernia, gastroduodenal angiodysplasia, Dieulafoy lesions, gastric antral vascular ectasias, and peptic ulcers. Moreover, endoscopy offers therapeutic options if a lesion is found in addition to establishing a diagnosis.

A colonoscopy is less likely to be helpful because the blood detected on nasogastric lavage suggests an upper gastrointestinal source. Wireless capsule endoscopy may be helpful if a repeat upper endoscopy is normal to assess the remainder of the small bowel; however, in contrast to endoscopy, capsule endoscopy does not offer therapeutic options. A radiolabeled red blood cell scan would not be the next test of choice; the results are nonspecific and would delay diagnosis and therapy that could be delivered more rapidly with endoscopy. In double-balloon enteroscopy, deep intubation of the small bowel is achieved by using a two-balloon technique to anchor the endoscope and assist in advancement. The procedure is lengthy and requires prolonged sedation, although it offers diagnostic and therapeutic capabilities. This test is reserved until a more proximal source of bleeding has been excluded and wireless capsule endoscopy has been performed. The capsule would direct whether the double-balloon enteroscope is to be introduced via the mouth (for jejunal abnormalities) or anus (ileal abnormalities).

Key Point

  • Repeat upper endoscopy in a patient with obscure upper gastrointestinal bleeding will identify a bleeding source in a significant proportion of patients.