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Mechanical small bowel obstruction — USMLE Step 3 MCQ

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HardSurgery (post-operative, follow-up)Mechanical small bowel obstructionUSMLE Step 3

A stable patient with adhesive partial small-bowel obstruction has received nasogastric decompression, intravenous fluid, electrolyte correction, and serial surgical examinations for 48 hours. Pain and distention persist, but there is no fever, leukocytosis, acidosis, peritonitis, closed loop, or reduced bowel-wall enhancement. What is the best next step?

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Correct answer: C — Administer water-soluble enteral contrast and follow its transit under continued surgical observation

The best answer is “Administer water-soluble enteral contrast and follow its transit under continued surgical observation”. In partial SBO without ischemia or peritonitis, an initial nonoperative trial is appropriate. EAST supports a water-soluble contrast study when obstruction has not resolved by 48 hours; colonic transit predicts successful nonoperative resolution, and the agent may also accelerate bowel function. Failure by roughly day 3–5 or clinical deterioration prompts operation, but 48 hours alone does not mandate laparotomy.

Reference: EAST Practice Management Guideline: Small-Bowel Obstruction: https://www.east.org/education-resources/practice-management-guidelines/details/smallbowel-obstruction-evaluation-and-management-of