Cholecystoduodenal Fistula

Cholecystoduodenal fistula is an abnormal communication between the gallbladder and the duodenum. It is the commonest cholecystoenteric fistula, making up about 70 to 80% of cases, and complicates about 0.5 to 1% of cholelithiasis. It affects older patients, with women more than men, and the mean age is about 65 years.

Cause: chronic or recurrent acute cholecystitis in which a large gallstone erodes through the inflamed gallbladder wall into the adherent duodenum (pressure necrosis). Other causes include peptic ulcer, gallbladder carcinoma and previous biliary surgery.

Consequences

• Pneumobilia and cholangitis, from reflux of duodenal content into the biliary tree
• Gallstone ileus when the stone passes distally and impacts, usually in the terminal ileum
• Bouveret syndrome, in which a stone impacts in the duodenum or pylorus and causes gastric outlet obstruction
• Gastrointestinal hemorrhage and gallbladder cancer (in about 15%)

Gallstone ileus accounts for about 1 to 4% of mechanical small bowel obstruction in general, and up to 25% in patients over 65 years.

• Often asymptomatic for years, or recurrent biliary colic and dyspepsia
• Cholangitis with fever, jaundice and right upper quadrant pain
• Bouveret syndrome: nausea, vomiting (non-bilious), early satiety and hematemesis
• Gallstone ileus: intermittent colicky pain (tumbling obstruction), vomiting and distension
• Red flags: persistent vomiting, hematemesis, signs of obstruction, sepsis and jaundice

1. CT of the abdomen with intravenous contrast is the investigation of choice (sensitivity about 90 to 95%): pneumobilia, a collapsed gallbladder adherent to the duodenum, an ectopic gallstone, and the Rigler triad (pneumobilia, small bowel obstruction and an ectopic stone).
2. Upper gastrointestinal endoscopy: shows the fistula opening and any stone impacted in the duodenum or pylorus.
3. Ultrasound: a contracted, thick-walled gallbladder with stones and pneumobilia.
4. Abdominal radiograph: air in the biliary tree and dilated small bowel loops.
5. Laboratory tests: liver function, white cell count, C-reactive protein, lactate, and electrolytes.

Differentials: gallstone ileus without a fistula, cholecystocolonic fistula, peptic ulcer disease, gastric outlet obstruction from other causes, gallbladder carcinoma, choledochoduodenal fistula.

1. Asymptomatic fistula: treat with elective cholecystectomy if the patient is fit. Otherwise observe.
2. Cholangitis: piperacillin-tazobactam 4.5 g IV every 6 hours for 5 to 7 days, and biliary decompression by ERCP if needed.
3. Bouveret syndrome: endoscopic stone extraction or fragmentation (mechanical lithotripsy, laser, electrohydraulic lithotripsy) in the first attempt. If this fails, laparotomy with gastrotomy or duodenotomy and extraction of the stone through a longitudinal incision, closed transversely.
4. Gallstone ileus: resuscitation, nasogastric decompression and surgical enterolithotomy through a longitudinal enterotomy proximal to the impaction, closed transversely. Run the whole bowel to look for additional stones (about 10 to 15%).
5. Fistula management:
   • One-stage repair (enterolithotomy, cholecystectomy and fistula closure) in fit patients with low-risk anatomy, which prevents recurrent ileus and cholangitis, but carries higher morbidity.
   • Enterolithotomy alone in frail or unstable patients, with later interval cholecystectomy if the patient recovers (recurrent ileus occurs in about 5%).
   • Close the duodenal defect in two layers, or patch with the omentum.
6. Perioperative prophylaxis: cefazolin 2 g IV with metronidazole 500 mg IV before incision, continued for 24 hours, with enoxaparin 40 mg SC daily for 7 days. Resuscitate with IV crystalloid 20 mL/kg initially.
7. Complications: mortality 10 to 20% in elderly patients with gallstone ileus, anastomotic leak, duodenal leak, wound infection, recurrent ileus and cholangitis.

Follow-up at 2 and 6 weeks. Counsel on early return for vomiting, abdominal pain or jaundice.