Large Bowel Gallstone Ileus: Rare Spontaneous Passage Through a Cholecystocolonic Fistula.

Gallstone ileus is a rare but serious complication of biliary disease that causes a mechanical obstruction in the gastrointestinal tract. Diagnosing gallstone ileus can be challenging, and if not managed quickly, it may result in severe complications. Due to frequent delays in diagnosis, this condition is associated with high morbidity and mortality rates. We report the case of a 53-year-old man who presented with right upper quadrant abdominal pain and constipation. The initial computed tomography (CT) scan revealed that these symptoms were due to a large bowel obstruction in the proximal sigmoid colon. Although a flexible sigmoidoscopy was scheduled, the patient spontaneously passed the stone in his stool before the procedure. The gallstone measured 5.5 cm x 3.9 cm, exceeding the average size of 2-5 cm reported in previous studies and ranking among the largest stones documented in gallstone ileus cases. Moreover, the size of the stone in our case exceeded the largest gallstone previously reported to pass with conservative measures in that sample. This case is notable because of the occurrence of gallstone ileus in the large bowel within an unexpected patient demographic. Furthermore, the gallstone was notably large yet passed into the stool with minimal complications.