A 70-year-old woman presents with 3 days of colicky abdominal pain, distension, and bilious vomiting. Plain abdominal radiograph shows dilated small bowel loops, pneumobilia, and a radio-opaque shadow in the right iliac fossa. What is the most likely diagnosis?
- A Gallstone ileus ✓
- B Cholangitis with septic ileus
- C Emphysematous cholecystitis
- D Retroperitoneal duodenal perforation
Correct answer: A. Gallstone ileus
Explanation
The combination of small bowel obstruction, pneumobilia, and an ectopic gallstone is Rigler's triad, the classic radiographic picture of gallstone ileus. It results from a cholecystoduodenal fistula allowing a large stone to impact usually at the terminal ileum, the narrowest point of the small bowel. Emphysematous cholecystitis causes gas in the gallbladder wall, not the biliary tree with distal small bowel obstruction, which excludes option C.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
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