What could cause bile to be present in the peritoneum after a patient with a history of bile duct obstruction, possibly due to malignancy or gallstones, undergoes a percutaneous Self-Expanding Metal Stent (SEMS) placement?

Causes of Bile in the Peritoneum After Percutaneous SEMS Placement

Bile in the peritoneum after percutaneous SEMS placement most commonly results from bile leak at the percutaneous access tract site, perforation of the bile duct during catheter manipulation, or stent-related complications including migration and ductal injury.

Primary Mechanisms of Bile Peritonitis

Percutaneous Access Tract Complications

• Bile leakage along the percutaneous tract is the most common cause when SEMS is placed via a percutaneous approach, occurring as bile escapes through the liver parenchyma and capsule into the peritoneal cavity 1
• The risk increases significantly when contrast is injected under high pressure during the procedure, which can cause cholangio-venous reflux and exacerbate bile extravasation 1
• Inadequate tract maturation before converting from external to internal drainage increases leak risk, as the fistulous tract between liver and bile duct has not sealed properly 2

Direct Bile Duct Injury

• Perforation of the common bile duct or hepatic ducts can occur during guidewire manipulation, catheter advancement, or stent deployment, particularly in non-dilated systems where technical difficulty is higher 1
• Percutaneous biliary procedures carry a 6.8% major complication rate including CBD perforation, duodenal perforation, and bile peritonitis 1
• Bile duct wall injury from stent deployment itself can create a perforation point, especially with covered SEMS that exert radial force 1

Stent Migration Complications

• Covered SEMS migration occurs in approximately 10% of cases and can cause bile leak if the stent moves proximally or distally, leaving the obstruction site unprotected 1
• Migration is more common with covered versus uncovered stents due to the silicone coating preventing tissue ingrowth 1
• Distal migration with sphincterotomy increases complication rates including perforation and bleeding 3

Secondary Mechanisms

Stent-Related Ductal Injury

• Tissue hyperplasia and pressure necrosis from prolonged stent placement can weaken the bile duct wall, creating delayed perforation sites 1
• Stent impaction or rotation within the bile duct can cause direct mechanical injury to the ductal wall 4
• The radial expansion force of SEMS may exceed the tensile strength of diseased or inflamed bile duct tissue, causing rupture 5

Inadequate Drainage Leading to Leak

• If the stent fails to adequately decompress the biliary system (due to malposition, occlusion, or incomplete expansion), elevated intraductal pressure forces bile through the weakest point—often the percutaneous access site 1, 2
• Injection of contrast proximal to a complete obstruction during stent placement can cause ductal rupture from acute pressure elevation 1

Critical Pitfalls to Avoid

Technical Considerations

• Never inject contrast under high pressure in an obstructed system, as this dramatically increases perforation and bile leak risk 1
• Ensure adequate biliary decompression is achieved before removing external drainage catheters; premature removal with incomplete stent function leads to bile accumulation and leak 2
• In non-dilated bile ducts, percutaneous access is technically more challenging with higher complication rates—consider endoscopic approaches first when feasible 1, 6

Stent Selection Issues

• Covered SEMS have higher migration rates than uncovered stents (10% vs. lower rates), increasing bile leak risk 1
• Avoid sphincterotomy before covered SEMS placement as this increases overall complication rates including migration, bleeding, and perforation 3
• Plastic stents may be preferable in some benign conditions to avoid the tissue ingrowth and removal difficulties associated with bare metal stents 1

Management Implications

Immediate Recognition

• Clinical signs include bilious drain output (if drain present), peritoneal signs, fever, and worsening liver enzymes despite stent placement 6
• Imaging with CT will demonstrate free fluid in the peritoneum and may show contrast extravasation if performed during cholangiography 6

Therapeutic Response

• Broad-spectrum antibiotics (piperacillin/tazobactam, imipenem/cilastatin, meropenem, or ertapenem) should be initiated immediately for bile peritonitis 1, 6
• Percutaneous drainage of bile collections is essential to control sepsis 6
• Endoscopic sphincterotomy with additional stent placement may be needed to reduce transpapillary pressure gradient and allow preferential bile flow into the duodenum rather than through the leak 6, 7
• Surgical repair is reserved for major bile duct injuries with complete loss of continuity that cannot be managed endoscopically 6, 7