EP423 - Cholecystocolonic Fistula Secondary to Chronic Cholecystitis in an Intravenous Drug User: A Rare Complication of Delayed Presentation

Purpose/Background: Cholecystocolonic fistula is a rare biliary-enteric fistula, occurring in < 1% of patients with cholelithiasis and comprising 10-20% of internal biliary fistulas. It arises from chronic inflammation and adhesion formation between the gallbladder and adjacent bowel, leading to perforation and fistula. Diagnosis can be challenging due to nonspecific symptoms and overlapping imaging findings.

This case describes a cholecystocolonic fistula in a young male with untreated chronic cholecystitis and intravenous drug use (IVDU), underscoring how delayed care can result in advanced biliary disease.

Methods/Interventions: A 35-year-old male with IVDU presented with seven months of intermittent right upper quadrant pain, self-treated with intravenous opioids. He had sought medical attention previously but left against advice or was denied intervention. On admission, he was afebrile but acutely ill, with leukocytosis and mild alkaline phosphatase elevation.

CT imaging revealed marked right upper quadrant inflammation, gallbladder wall thickening, and adherence to the transverse colon. A HIDA scan showed no gallbladder filling, and MRI confirmed severe pericholecystic and colonic inflammation with concern for malignancy.

Initial management with bowel rest and IV antibiotics failed, prompting surgery. An open cholecystectomy via midline incision was performed, revealing dense adhesions between the gallbladder and hepatic flexure. Dissection identified a mature cholecystocolonic fistula. Given the inflammation and colonic involvement, a right hemicolectomy with high ligation of the mesenteric vessels was undertaken.

Results/Outcomes: The patient tolerated surgery well and was discharged on postoperative day three without complication.

Pathology confirmed a mature cholecystocolonic fistula with intramural abscess formation. A 2 cm tubular adenoma was found in the resected colon, negative for high-grade dysplasia or carcinoma. All 20 lymph nodes were benign.

This case demonstrates that chronic cholecystitis with delayed management can lead to complex biliary-colonic fistulas requiring extensive resection to prevent morbidity.

Conclusion/Discussion: Cholecystocolonic fistula is an uncommon but serious complication of chronic cholecystitis, usually seen in elderly patients with gallstones. This case is unique for its occurrence in a young man where IVDU contributed to delayed presentation and advanced inflammation.

Preoperative diagnosis remains difficult; however, CT, MRCP, and HIDA scans can suggest the condition. Intraoperative recognition is frequent, and management depends on disease extent. While simple cholecystectomy and fistula takedown may suffice in limited cases, extensive inflammation may require segmental colectomy for definitive treatment and to rule out malignancy.

This case highlights the need for clinical suspicion in atypical presentations of chronic cholecystitis and reinforces the importance of timely, comprehensive surgical management to prevent recurrence and missed pathology.

Microscopic photograph showing fistulous tract involving colonic wall, H@E stain, 5X magnification