S3248 A Rare Complication of Gallstone Pancreatitis: Cholecystocolonic Fistula

Introduction: Cholecystocolonic fistulas are rare, occurring in less than 0.5% of patients undergoing cholecystectomy. However, when they do develop, they can lead to complications such as colonic perforation, gallstone ileus, and infection. Here, we present a case of a patient who developed a cholecystocolonic fistula alongside gallstone-induced pancreatitis. Case Description/Methods: An 81-year-old woman with a history of hyperlipidemia, and hypertension presented to the emergency department with acute onset abdominal pain. Laboratory results revealed a total bilirubin of 1.0 mg/dL, AST of 103 U/L, ALT of 119 U/L, ALP of 880 U/L, lipase of 6,421 U/L, and a WBC count of 11.8 K/mcL. Physical examination showed tenderness in the epigastric area, without guarding or rigidity. Gallbladder ultrasound revealed a 7 mm common bile duct diameter and questionable pneumobilia. Computed tomography of the abdomen demonstrated an air-fluid level in the pancreatic head/uncinate process, along with small-volume pneumobilia. Magnetic resonance cholangiopancreatography (MRCP) confirmed the presence of pneumobilia and suspected a communication between the gallbladder and the hepatic flexure of the colon, raising concern for a cholecystocolonic fistula. Several filling defects were also identified within the extrahepatic bile ducts, including a 1 cm dependent filling defect in the distal common bile duct. Given these findings, the patient underwent colonoscopy and endoscopic retrograde cholangiopancreatography (ERCP). During ERCP, contrast was observed flowing from the gallbladder into the colon under fluoroscopy. Balloon sweep of the common bile duct revealed multiple small stones and 1 larger stone measuring approximately 12 mm. Colonoscopy identified a fistulous connection between the gallbladder and right colon, which was marked with a tattoo. The following day, the patient underwent a successful right hemicolectomy, cholecystectomy, and takedown of the cholecystocolonic fistula using the previously placed tattoo as a guide. Postoperatively, liver chemistries improved in a stepwise fashion. The patient tolerated the procedure well, with no complications, and was discharged in stable condition. Discussion: Cholecystocolonic fistulas are rare complications of gallstone disease, typically presenting with large gallstones that compress the gallbladder and colon. This case highlights the clinical presentation, diagnostic evaluation, and surgical management of this unusual complication. Timely identification and appropriate management are crucial in preventing further complications such as gallstone ileus or bowel perforation.