Gallstone Ileus: A Case Report of an Uncommon Cause of Mechanical Intestinal Obstruction.

Biliary ileus is an uncommon cause of mechanical intestinal obstruction secondary to the passage of gallstones into the gastrointestinal tract through a cholecystoenteric fistula. Its nonspecific clinical presentation contributes to diagnostic and therapeutic delays. Although computed tomography is considered the diagnostic modality of choice, identification of Rigler's triad on plain abdominal radiography may provide an early diagnostic orientation in patients with a compatible clinical presentation. We present the case of a 58-year-old male patient without known biliary disease who presented with abdominal pain, bilious vomiting, and signs of intestinal obstruction. Plain abdominal radiography demonstrated pneumobilia, dilated bowel loops, and an ectopic gallstone at the ileocecal region, findings consistent with Rigler's triad. Given the high clinical and radiographic suspicion of biliary ileus, exploratory laparotomy was performed, revealing a gallstone impacted in the distal ileum. Isolated enterolithotomy was carried out with favorable postoperative outcomes. This case highlights the importance of maintaining a high index of suspicion in patients presenting with subacute mechanical intestinal obstruction, even in the absence of documented biliary disease, in order to facilitate timely diagnosis and appropriate surgical management.