S3441 Cholecystoenteric Fistula Presenting With Acute Cholecystitis and Acute Diverticulitis

Introduction: Cholecystoenteric fistulas complicate 0.4%–1.9% of gallstone disease and usually involve the duodenum; colonic fistulas are rarer but more morbid. Chronic gallbladder inflammation, pressure necrosis from stones, and adjacent diverticulitis can converge to form a cholecystocolic fistula. Because presentations mimic routine cholecystitis or diverticulitis, cross-sectional imaging is essential for timely diagnosis. Case Description/Methods: A 59-year-old man with heavy alcohol and 30-pack-year smoking history had 3 days of right-upper-quadrant pain, nausea, and bilious emesis. Vitals: temperature 38.4°C, heart rate 110, blood pressure 146/86 mmHg. Labs: White Blood Cells (WBC) 14.2 × 10⁹/L, Alanine Aminotransferase (ALT) 67 U/L; bilirubin and lipase normal. Computed Tomography showed a gas-filled, thick-walled gallbladder with pericholecystic fluid plus segmental colonic thickening and fat stranding at the hepatic flexure. Magnetic Resonance Cholangiopancreatography (MRCP) confirmed gas within the gallbladder fundus abutting colon; Hepatobiliary Iminodiacetic Acid Scan (HIDA) failed to visualize the gallbladder. Blood cultures were sterile. Given severe local inflammation and ASA III status, interventional radiology placed a 10-Fr cholecystostomy tube; purulent bile grew amoxicillin-clavulanate–sensitive E. coli. After 2 days of piperacillin-tazobactam he completed oral amoxicillin-clavulanate. Symptoms and leukocytosis resolved, and he was discharged on day 5 with plans for elective cholecystectomy and possible colonic resection. Discussion: Colonic cholecystoenteric fistulas usually follow long-standing cholelithiasis but may also arise from contiguous diverticulitis. Pneumobilia or gallbladder gas without instrumentation strongly suggests a fistula. For unstable or high-risk patients, percutaneous cholecystostomy provides rapid source control, decompresses the biliary tree, and lets inflammation subside before definitive surgery, reducing operative risk. This patient’s quick recovery with drainage and culture-directed antibiotics supports the staged approach; elective cholecystectomy with en-bloc fistula takedown or limited colonic resection remains definitive to prevent recurrent infection or gallstone ileus.