Abstract
Mechanical bowel obstruction due to a giant colonic calculus is an exceedingly rare clinical entity, typically associated with gallstone ileus or migration through a cholecystocolonic fistula. This case report describes the clinical presentation, diagnostic process, and treatment of an 81-year-old male with a history of cholelithiasis who developed acute mechanical large bowel obstruction due to a 5 cm sigmoid colon calculus. The patient, with comorbidities including diabetes mellitus, hypertension, chronic renal failure, prior prostatectomy, and appendectomy, presented with abdominal pain, nausea, and vomiting. Physical examination revealed tenderness in the left lower quadrant without rebound or guarding, indicating no evidence of perforation. Laboratory findings showed leukocytosis (white blood cell count [WBC]: 12,000/μL, neutrophil percentage: 85.2%) and elevated C-reactive protein [CRP] (33 mg/L). Non-contrast abdominal computed tomography (CT) revealed a 5 cm calculus in the sigmoid colon, with proximal dilatation, air-fluid levels, and pneumobilia. A prior hepatobiliary ultrasound had documented a 49 mm gallstone, suggesting migration via a cholecystocolonic fistula. Sigmoidoscopy, performed using an Olympus CF-HQ190 colonoscope with tripod grasping forceps, successfully extracted the calculus. Due to the patient's advanced age and significant comorbidities, surgical repair of the cholecystocolonic fistula was not pursued. A follow-up hepatobiliary ultrasound one month post-procedure revealed no residual gallstones. The patient achieved rapid recovery and was discharged the following day. This case is notable for the exceptionally large 5 cm calculus, which is rare compared to the 2-3 cm stones typically reported, and highlights the efficacy of sigmoidoscopy in managing such cases in elderly patients with significant comorbidities.