A biloma is a contained collection of bile that has leaked outside the bile ducts and pooled somewhere it doesn’t belong, either inside the liver or elsewhere in the abdominal cavity. The term was coined in 1979 and originally referred only to encapsulated bile collections outside the liver, but it now describes any well-defined bile collection found outside the biliary tree, whether fully encapsulated or not.
Most people encounter this term after abdominal surgery, particularly gallbladder removal or liver surgery, when imaging reveals an unexpected fluid collection. Understanding what a biloma is, how it forms, and what happens next can make a stressful post-surgical finding much easier to navigate.
How a Biloma Forms
Your liver constantly produces bile, which flows through a network of small ducts that merge into larger ones and eventually drain into the small intestine. When any part of this network is damaged, bile can leak out. What happens next depends on how fast the leak is.
In most cases, bile leaks slowly. The bile acids irritate surrounding tissue (they have detergent-like properties that break down cells), triggering low-grade inflammation. Over days to weeks, this inflammation produces scar tissue that walls off the leaking bile into a contained pocket. That pocket is the biloma. In faster leaks, the body may not have time to form this capsule before symptoms appear, and loose bile in the abdominal cavity can cause a more serious condition called biliary peritonitis.
Common Causes
The vast majority of bilomas result from some form of injury to the bile ducts. The most common causes include:
- Surgery: Gallbladder removal (cholecystectomy) and liver resection are the most frequent culprits. In one study of 565 patients who had partial liver removal, bile leaks occurred in about 10% of cases, with roughly two-thirds of those leaks forming bilomas visible on imaging.
- Abdominal trauma: Blunt injuries (like a car accident) or penetrating injuries (like a stab wound) can damage bile ducts.
- Liver biopsies and other procedures: Needle-based procedures that pass through the liver can occasionally nick a bile duct.
In rare cases, bilomas form spontaneously from conditions that weaken or obstruct the bile ducts, such as gallstones or tumors that cause enough pressure to rupture a duct.
Where Bilomas Develop
Bilomas fall into two broad categories based on location. Intrahepatic bilomas form inside the liver itself, within the liver tissue surrounding the damaged duct. Extrahepatic bilomas collect outside the liver, often pooling near the gallbladder bed, under the liver, or elsewhere in the abdominal cavity. The location matters because it influences both symptoms and how the biloma is treated. An intrahepatic biloma may sit quietly inside the liver for some time, while an extrahepatic one is more likely to irritate surrounding structures and cause noticeable discomfort.
Symptoms to Watch For
Small bilomas sometimes cause no symptoms at all and are discovered incidentally on imaging done for other reasons. When symptoms do appear, they typically develop days to weeks after the triggering event and often include persistent abdominal pain (particularly in the upper right side), fever, and nausea. After a gallbladder removal, the most telling sign is simply not recovering as smoothly as expected. Persistent pain, low-grade fevers, or a general sense that something isn’t right in the days following surgery warrants attention.
If the biloma becomes infected, symptoms intensify: higher fevers, worsening pain, and signs of systemic illness. In the worst-case scenario, a biloma can rupture into the abdominal cavity, causing biliary peritonitis, which can progress to multi-organ failure and requires emergency surgery.
How a Biloma Is Diagnosed
Bilomas are typically found on imaging studies. On CT scans and ultrasound, they appear as well-defined fluid collections, but they can look similar to other post-surgical findings like abscesses, blood collections (hematomas), or benign cysts. Telling them apart matters because treatment differs significantly.
MRI can help distinguish a biloma from a hematoma. On MRI, bilomas show a characteristic pattern that differs from blood collections: bile appears differently from blood on specific imaging sequences, giving radiologists a reliable way to tell the two apart. A specialized nuclear medicine scan using a radioactive tracer that the liver processes into bile can also confirm the diagnosis by showing the tracer accumulating in the biloma, proving the fluid is bile rather than blood or pus.
Bilomas also need to be differentiated from lymphoceles (collections of lymph fluid), pancreatic pseudocysts, and seromas (collections of clear fluid). The clinical context, especially a recent surgery or injury involving the bile ducts, helps narrow the diagnosis considerably.
Treatment Options
Treatment depends on the biloma’s size, whether it’s causing symptoms, and whether the underlying bile leak is still active. There is no single consensus protocol; each case is managed individually, ideally at a center with experienced specialists in hepatobiliary surgery, advanced endoscopy, and interventional radiology.
Small, asymptomatic bilomas sometimes resolve on their own as the bile leak seals and the body gradually reabsorbs the fluid. Larger or symptomatic bilomas typically require drainage, and the first step is usually percutaneous drainage: a radiologist places a thin catheter through the skin and into the biloma under imaging guidance, allowing the bile to drain externally. This diverts bile away from the leak and gives the damaged duct a chance to heal.
If the leak persists, additional procedures may be needed to address the source. Endoscopic approaches use a scope passed through the mouth and into the small intestine to place a small stent across the leaking area, reducing pressure in the bile ducts and redirecting bile flow away from the leak. Studies show clinical success rates of roughly 84% to 87% with endoscopic techniques. The stents typically stay in place for a median of about 30 to 50 days before being removed, though individual cases vary widely.
Surgery is reserved for cases where the bile duct is completely transected or when less invasive approaches fail. Before any procedure, infections are treated aggressively with antibiotics, and the patient’s overall condition is stabilized.
What Recovery Looks Like
With successful drainage and management of the underlying leak, most bilomas resolve fully. If you have a percutaneous drain placed, you may go home with it in place and return for follow-up imaging to confirm the biloma is shrinking and the leak has stopped. The drain is removed once output drops and imaging shows resolution.
Endoscopic stent placement allows for fully internal drainage, meaning no external tubes. Resolution times with endoscopic approaches tend to be somewhat shorter, and hospital stays are typically briefer compared to external drainage alone. Follow-up CT scans track the biloma’s size; success is generally defined as a greater than 50% reduction in diameter along with resolution of symptoms like pain and fever.
The key risk during recovery is infection of the bile collection. An infected biloma essentially becomes an abscess and requires more aggressive drainage and prolonged antibiotic treatment. Ongoing monitoring during the weeks after diagnosis helps catch this early.