A 70-year-old woman presents with colicky abdominal pain, distension and vomiting. Plain abdominal radiograph shows dilated small bowel loops, and CT demonstrates small bowel obstruction with a calcified focus in the right iliac fossa and gas within the biliary tree. The combination of these three findings is known as:

• A Rigler sign
• B Mercedes Benz sign
• C String of beads sign
• D Rigler triad ✓

Explanation

Rigler triad consists of pneumobilia, small bowel obstruction, and an ectopic calcified gallstone, and it indicates gallstone ileus caused by a cholecystoduodenal fistula. It classically affects elderly women after repeated bouts of cholecystitis. Rigler sign refers to gas on both sides of the bowel wall in pneumoperitoneum, the Mercedes Benz sign describes fissured gallstones on plain film, and the string of beads sign describes small bowel obstruction on erect radiographs.

Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.