CGRN MCQ 2 — Questions and Answers
Question 1: Which portion of the colon is most commonly affected by ischemic colitis?
- Cecum
- Splenic flexure (watershed area) (Correct answer)
- Rectum
- Ascending colon
Correct answer: Splenic flexure (watershed area)
The splenic flexure is a watershed area between SMA and IMA territories, most vulnerable to ischemia.
The splenic flexure (Griffith's point) and rectosigmoid junction (Sudeck's point) are watershed areas. Clinical presentation: sudden left-sided pain, urgency, bloody diarrhea. Most cases (80-85%) are non-gangrenous and resolve with supportive care.
Question 2: A patient with cirrhosis develops spontaneous bacterial peritonitis. What is the most common causative agent?
- Staphylococcus aureus
- Escherichia coli (Correct answer)
- Bacteroides fragilis
- Clostridium perfringens
Correct answer: Escherichia coli
E. coli accounts for approximately 40% of SBP cases via bacterial translocation from the gut.
SBP occurs in 10-30% of cirrhotic patients with ascites. Typically monomicrobial. Diagnosis: ascitic fluid PMN ≥250 cells/mm³. Treatment: IV ceftriaxone/cefotaxime plus IV albumin. Survivors need lifelong prophylaxis.
Question 3: Which serum marker is most useful for monitoring ulcerative colitis disease activity?
- CEA
- Fecal calprotectin (Correct answer)
- Alpha-fetoprotein
- CA 19-9
Correct answer: Fecal calprotectin
Fecal calprotectin directly reflects intestinal inflammation and correlates closely with endoscopic disease activity.
Fecal calprotectin has >90% sensitivity for moderate-severe inflammation. Useful for distinguishing IBD from IBS, monitoring therapy response, and predicting relapse. Normal <50 mcg/g, borderline 50-200, elevated >200.
Question 4: What is the initial management for acute esophageal food bolus impaction?
- Emergent surgery
- IV glucagon trial, then flexible endoscopy if unsuccessful (Correct answer)
- Observation for 72 hours
- Barium swallow to localize
Correct answer: IV glucagon trial, then flexible endoscopy if unsuccessful
Start with IV glucagon 1 mg, then endoscopic removal if the bolus does not pass.
Complete obstruction (drooling) requires emergent endoscopy within 2-6 hours. IV glucagon may allow passage in 12-50% of cases. Endoscopic push or pull technique. NEVER perform barium swallow. Always evaluate for underlying cause (75-100% have structural abnormality).
Question 5: A 4 cm smooth submucosal mass is found in the stomach incidentally. What is the most likely diagnosis?
- Adenocarcinoma
- Gastrointestinal stromal tumor (GIST) (Correct answer)
- Hyperplastic polyp
- Lipoma
Correct answer: Gastrointestinal stromal tumor (GIST)
GISTs are the most common mesenchymal tumors of the GI tract, 60-70% occurring in the stomach.
GISTs originate from interstitial cells of Cajal. EUS shows hypoechoic mass from the 4th (muscularis propria) layer. c-KIT (CD117) positive in ~95%. Surgical resection for tumors >2 cm. Imatinib for unresectable/metastatic disease.
Question 6: What is the most common cause of acute pancreatitis?
- Alcohol consumption
- Gallstones (Correct answer)
- Hypertriglyceridemia
- Medications
Correct answer: Gallstones
Gallstones account for approximately 40% of acute pancreatitis cases.
Gallstone pancreatitis occurs when a stone lodges at the ampulla of Vater. Second most common: alcohol (30%). Initial evaluation: RUQ ultrasound. Cholecystectomy during same admission recommended to prevent recurrence (30-40% without surgery).
CGRN MCQ 2
Which portion of the colon is most commonly affected by ischemic colitis?