Biliary Colonic Fistula Formation in the Setting of Obstructive Cholelithiasis

ABSTRACT

Biliary enteric fistulas are rare form of internal biliary fistula encountered in <1% of patients with biliary disease while cholecystocolic fistulas are even rarer with reported incidence of 0.06%–0.14% in patients undergoing cholecystectomy. We present a case of biliary colonic fistula that developed in the context of obstructive cholelithiasis, emphasizing a pathological process involving chronic inflammation due to gallstone with a gradual erosion into the surrounding structure. A high index of suspicion is required for diagnosis, given the presentation with nonspecific symptoms. Given the risk of imminent cholangitis, sepsis, and liver parenchymal damage, early treatment with cholecystectomy with the closure of the fistula is recommended.

INTRODUCTION

A biliary fistula is an abnormal connection between the biliary system and another organ, cavity, or free surface. When this connection occurs within the body, it is called an internal biliary fistula (IBF); when it extends to the abdominal wall, it is called an external biliary fistula. IBFs are rare and are often found in patients with chronic gallstone disease. In this case, we will discuss a specific case of a cholecystocolonic fistula in the setting of acute cholangitis.

CASE REPORT

A 60-year-old African American man with no significant medical history had a 3-month history of intermittent nausea and vomiting with reported 40 lbs weight loss. He presented to an outside hospital with syncopal episodes in the setting of persistent nausea and vomiting for the last 2 weeks. He was found to be in septic shock on presentation with a suspected intra-abdominal infection, for which he received broad-spectrum antibiotics. Given hyperbilirubinemia, he underwent extensive workup, including computed tomography of the abdomen/pelvis, abdominal ultrasound, and magnetic resonance cholangiopancreatography (MRCP), which showed biliary obstruction at the junction of the cystic duct with hepatic duct dilation. The patient subsequently had endoscopic retrograde cholangiopancreatography (ERCP), which showed filling defects at the bifurcation of hepatic ducts; it was unclear whether the patient had stones or a mass. Cytology brushings were unremarkable. Given the concern for cholangiocarcinoma due to equivocal radiographic findings, he was transferred to our facility for further evaluation. On presentation, the patient was afebrile and hemodynamically stable. The patient reported no abdominal pain or jaundice. He denied any past biliary disorder or a family history of malignancy. Laboratory analysis was remarkable for aspartate transaminase of 69 U/L, alanine transaminase of 77 U/L, alkaline phosphatase of 298 U/L, total bilirubin of 1.3 mg/dL, and hemoglobin of 11.5 × 10⁹ cells/L. Given no symptoms and hemodynamic stability, the patient was provided supportive treatment.

Radiological interpretation of the outside imaging studies, including an MRCP, suggested Mirizzi syndrome with possible cystic stones as filling defects compressing on the common bile duct (CBD). MRCP also demonstrated possible fistulation between the gallbladder and the colon at the hepatic flexure. However, a mass could not be excluded given the eccentric filling defect of the proximal CBD and intermediate signal due to lack of contrast (Figure 1). The patient underwent an abdominal magnetic resonance imaging, which showed no identifiable mass but multiple stones in the cystic duct with mass effect on the CBD at that level and subsequent intra and extrahepatic ductal dilation. With a concern for Mirizzi syndrome, the surgery team planned to perform exploratory laparotomy with possible cholecystectomy. Before surgery, the patient underwent a colonoscopy due to the concern for fistulous communication with the colon. The site of the cholecystocolonic fistula was identified and tattooed (Figure 2).

Figure 1.

Magnetic resonance cholangiopancreatography demonstrated intrahepatic and proximal extrahepatic biliary duct dilatation with abrupt cutoff due to an irregular filling defect of the proximal common bile duct.

Figure 2.(.

A) Colonoscopy identified a fistula (left arrow) in the transverse colon at the hepatic flexure (right arrow). (B) Colonic fistula, the site was later marked with tattoo and clip placement.

The patient subsequently underwent exploratory laparotomy with the division of the transverse colon from the gallbladder fistula. The gallbladder infundibulum was impacted by large gallstones. However, there was no clear dissection plane between the gallbladder and the CBD as there was no cystic duct, and the gallbladder infundibulum led straight into the bile duct, possibly highlighting the development of cholecystobiliary fistula with erosion of CBD wall (Mirizzi Type II). The gallbladder was removed, and the CBD was repaired over a 14-French T tube that was tunneled out through the abdominal wall for drainage. A Jackson-Pratt drain was also placed into the gallbladder fossa. After cholecystectomy was performed, the segment of the colon with the fistula was identified and resected with an end-to-end anastomosis. He did well after surgery, and his liver enzymes improved. Later, a cholangiogram through the T-tube confirmed the biliary system's patency and ensured no biliary leakage, stricture, or enteric fistula (Figure 3). The pathology report showed chronic cholecystitis and benign colonic tissue. The patient followed up in the gastroenterology and surgery clinic and continued to improve clinically with a plan to remove the biliary drains.

Figure 3.

Cholangiogram through the T-tube demonstrated a patent biliary system without evidence of biliary leakage, stricture, or enteric fistula.

DISCUSSION

Biliary enteric fistulas (BEF) are a rare type of IBF encountered in <1% of patients with biliary disease.¹ Of all the BEF, cholecystoduodenal (77%) and cholecystocolic (8%-23%) are the most common.^1,2 Cholecystocolic fistulas are incidentally discovered in 0.06% to 0.14% of patients undergoing cholecystectomy.¹ These fistulas are further characterized as primary and secondary fistulas.³ The primary fistulas develop due to long-standing inflammation, primarily due to chronic cholecystitis.³ Other causes of primary fistulas include colonic diverticulitis, biliary or colonic malignancy, and inflammatory bowel disease.^3,4 Meanwhile, secondary fistulas are the result of iatrogenic injury due to cholecystectomy.³

Studies have shown that primary BEF formation may involve an evolving process that develops through several stages, starting with external compression of the CBD due to an affected stone at the infundibulum or cystic duct (Mirizzi syndrome) where gall bladder and cystic duct begin to undergo erosion initially forming a cholecystocholedochal fistula and eventually erodes through the CBD and into the surrounding organs, developing the IBF.³ In our case, a similar pathological process involving chronic inflammation caused by gallstones and a gradual erosion into the surrounding structure can explain the formation of the cholecystoenteric fistula.

Symptoms of biliary-colonic fistula can vary, ranging from no symptoms at all to several nonspecific symptoms, including abdominal pain, nausea, weight loss, and dyspeptic symptoms.^4,5 Patients may also experience chronic diarrhea due to the malabsorption of bile acids, which bypass the normal circulation and enter the colon, producing excessive secretion of water and electrolytes as stimulated directly by the bile acids.^1,4,5 In some cases, patients may develop cholangitis and sepsis due to bacterial overgrowth and inflammation of the gallbladder and biliary tract, while others may present with small bowel obstruction with the passage of large stones into the alimentary tract.^1,4–6

Given nonspecific symptoms, BEF is usually not suspected and is mostly diagnosed intraoperatively; thus, a high index of clinical suspicion is required.⁷ Various diagnostic modalities have been used for evaluation including plain x-ray, abdominal ultrasound, upper gastrointestinal series, barium enema, computed tomography, MRCP, and ERCP; however, incidence of preoperative diagnosis remains low.^7,8 The presence of pneumobilia, a small, atrophic gallbladder adherent to neighboring organs or a shrunken, thick-walled gallbladder containing gallstones can suggest BEF.^8,9 However, given its diagnostic and therapeutic potential, some authors consider ERCP the primary diagnosis mode.^1,5,6 Interestingly, in our case, the fistula was not visualized during initial ERCP, likely to do stones with filling limitations, but was later identified on MRCP, again highlighting the need for high clinical suspicion to diagnose IBF. Therefore, if a high index of suspicion exists, a perioperative cholangiogram can be considered for a definitive diagnosis.

Given the risk of imminent cholangitis, sepsis, and liver parenchymal damage, early treatment is highly recommended.⁴ With primary BEF, cholecystectomy (open or laparoscopic) with the closure of the fistula (with or without segmental colonic resection) is considered the standard therapy for most patients.^3,6,10 For asymptomatic patients who are considered high-risk for surgery or have low life expectancy, some clinicians advocate for supportive care with symptomatic management.¹¹ Symptomatic management may include fat-soluble vitamin supplementation, prophylactic antibiotics, ERCP, and sphincterotomy (+/− stent placement).^11,12 ERCP with sphincterotomy (+/− biliary stent placement) may achieve intrabiliary pressure decompression and ultimately help the fistula close.^1,6,12

DISCLOSURES

Author contributions: M. Mushtaq, A. Khan, M. Tran, J. Walker, and S. Parupudi: Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; Drafting the work or reviewing it critically for important intellectual content; Final approval of the version to be published; and Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. M. Mushtaq is the article guarantor.

Financial disclosure: None to report.

Informed consent was obtained for this case report.