Inflammatory Bowel Disease USMLE Step 1 Practice Question
A 35-year-old man with a 6-year history of Crohn disease presents to the emergency department with a 3-day history of increased bloody diarrhea (8-10 stools daily), fever, and severe abdominal pain. He has been compliant with azathioprine 2 mg/kg daily for the past 2 years. Vital signs: temperature 39.1°C, heart rate 115/min, blood pressure 105/70 mmHg, respiratory rate 22/min, oxygen saturation 96% on room air. Physical examination reveals diffuse abdominal tenderness and mild distention without peritoneal signs. Abdominal X-ray shows colonic dilation of 7.2 cm with loss of haustra and thumbprinting. Laboratory studies: WBC 13,800/μL, hemoglobin 8.9 g/dL, albumin 2.8 g/dL, C-reactive protein 8.2 mg/dL. Stool testing for C. difficile toxin, enteric pathogens, and parasites are all negative. What is the most appropriate next step in management?
Answer choices
- AProceed immediately to total abdominal colectomy with ileostomy
- BInitiate infliximab 5 mg/kg IV infusion and continue azathioprine
- CObtain urgent CT abdomen/pelvis with contrast and start high-dose IV corticosteroids with NPO status and bowel restCorrect answer
- DPerform urgent colonoscopy with full mucosal biopsy to assess disease severity and guide therapy
- EIncrease azathioprine dose to 3 mg/kg and add oral ciprofloxacin for dysbiosis
- FStart high-dose oral mesalamine (4.8 g daily) and hydrocortisone enema twice daily
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