A 68-year-old woman presents with 2 days of distension, vomiting, and absolute constipation. She has a long history of symptomatic gallstones she never had treated. Plain abdominal radiograph shows dilated small bowel loops, pneumobilia, and a calcified opacity in the right iliac fossa. The most likely diagnosis is:

• A Carcinoma of the caecum
• B Mirizzi syndrome type II
• C Empyema of the gallbladder
• D Cholecystoduodenal fistula with gallstone ileus ✓

Explanation

Rigler's triad of pneumobilia, small bowel obstruction, and an ectopic gallstone identifies gallstone ileus, which follows erosion of a large stone through the gallbladder wall into the duodenum via a cholecystoduodenal fistula. The stone typically impacts at the narrowest point of the small bowel, the terminal ileum. Caecal carcinoma would explain obstruction in this age group but does not produce pneumobilia. Mirizzi syndrome causes obstructive jaundice from external common hepatic duct compression, not mechanical small bowel obstruction.

Reference: Bailey and Love's Short Practice of Surgery, 28th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.