A 78-year-old woman with previous recurrent right upper quadrant pain presents with colicky central abdominal pain, distension, and bilious vomiting. Plain X-ray shows dilated small bowel loops, gas in the biliary tree, and a calcified opacity in the right iliac fossa. What is the diagnosis?

• A Adhesive small bowel obstruction following silent pelvic inflammation
• B Gallstone ileus secondary to a cholecystoduodenal fistula ✓
• C Sigmoid volvulus with incidental cholelithiasis
• D Internal hernia through a paraduodenal defect

Explanation

Rigler's triad, pneumobilia plus small bowel dilatation with air fluid levels plus an ectopic calcified gallstone, is diagnostic of gallstone ileus. The stone enters the gut through a cholecystoduodenal fistula created by chronic inflammation and impacts usually at the narrow terminal ileum. Adhesions and paraduodenal hernias cannot explain pneumobilia, and sigmoid volvulus would show a grossly dilated colonic loop rather than small bowel obstructive pattern.

Reference: Bailey and Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.