Gallstone Ileus as an Occult Cause of Small Bowel Obstruction and Subsequent Large Bowel Obstruction: A Report of a Rare Case.

Gallstone ileus, a rare cause of mechanical bowel obstruction, occurs due to the formation of a cholecystenteric fistula allowing gallstones to migrate into the gastrointestinal tract. The condition occurs mostly in elderly patients, particularly women, and carries a significant mortality risk due to delayed diagnosis. This case report discusses a 77-year-old female patient with a history of chronic medical conditions, who self-presented with periumbilical pain, nausea, and reduced bowel movements. Initial imaging revealed pneumobilia and small bowel obstruction, leading to a diagnosis of partial obstruction attributed to adhesions. Despite surgical intervention and temporary symptom relief, the patient's condition deteriorated due to a subsequent colonic obstruction. The case was complicated by delayed recognition of gallstone ileus, as imaging initially misinterpreted the obstructive mass as a "stool ball" rather than a gallstone. Following diagnostic laparoscopy and subsequent exploratory surgeries, the patient was found to have a gallstone impacted in the rectum, leading to colonic ischemia and perforation. This resulted in progressive renal failure, respiratory failure, and ultimately, the patient's death in hospice care. This case underscores the diagnostic challenges of gallstone ileus and highlights two key delays: misattribution of obstructive symptoms to adhesions and failure to recognize colonic obstruction due to gallstone ileus. Early use of contrast-enhanced imaging and a high index of suspicion are crucial for timely diagnosis. This case emphasizes the importance of thorough inspection of the small bowel and ileocecal region during laparoscopy and the need for careful evaluation of imaging findings to improve patient outcomes in gallstone ileus cases.