Gallstone ileus due to a visible cholecystoduodenal fistula with pneumobilia CT diagnosis and surgical management: A case report.

Gallstone ileus is an uncommon cause of mechanical small-bowel obstruction, usually occurring in elderly patients with comorbidities. It results from migration of a gallstone through a cholecystoenteric fistula, most commonly a cholecystoduodenal fistula, with subsequent impaction within the bowel lumen. Although computed tomography (CT) is the established imaging modality for diagnosis, direct demonstration of the fistulous tract is not always straightforward in routine emergency imaging. We report the case of a 69-year-old woman with type 2 diabetes mellitus and ischemic heart disease who presented with a 5-day history of diffuse abdominal pain, recurrent vomiting, and obstipation. Plain abdominal radiography showed small-bowel dilatation and a faint right lower abdominal opacity suspicious for an ectopic gallstone but was not conclusive. Contrast-enhanced abdominopelvic CT demonstrated mechanical small-bowel obstruction, pneumobilia with air in the gallbladder lumen and biliary tree, and a laminated ectopic gallstone impacted within a right lower abdominal ileal loop. Multiplanar reformations clearly depicted an air-containing cholecystoduodenal fistula extending from the gallbladder neck to the duodenal bulb, while 3D volume-rendered reconstruction provided an intuitive overview of the ectopic calculus. The patient underwent urgent laparotomy with enterolithotomy and restoration of bowel continuity; cholecystectomy and fistula repair were deferred because of age and comorbidities. Recovery was uneventful. This case emphasizes the educational value of careful multiplanar CT review for direct fistula visualization, as accurate preoperative characterization of the fistula and obstructing stone can support individualized surgical planning in elderly high-risk patients.