Biloma

Usually simple in appearance, but may rarely have internal debris, blood products, etc.

No identifiable capsule/peripheral enhancement

• MR: Usually well-defined fluid collection, which is T2WI hyperintense and T1WI hypointense

Hepatobiliary contrast agents (e.g., Eovist) are excreted into biliary tree and may identify site of bile leak in hepatobiliary phase

Standard MRCP cannot definitively identify site of bile leak or differentiate biloma from other fluid collections

• Hepatobiliary scintigraphy: Focal accumulation of radiotracer outside biliary tree and bowel

• ERCP: Can delineate site of leakage and guide treatment

PATHOLOGY

• Most commonly the result of iatrogenic injury to biliary tract

Cholecystectomy (especially laparoscopic), radiofrequency ablation of focal hepatic lesions, percutaneous liver biopsy, liver transplantation

• Traumatic bile leaks due to blunt or penetrating trauma can occur but are relatively uncommon

CLINICAL ISSUES

• ERCP with sphincterotomy and plastic stent placement (to decrease biliary pressure and control leak) is effective in majority (> 90%) of cases

• Percutaneous drainage of collection (often under image guidance) if biloma is large, infected, or increasing in size

• Biloma associated with transection of extrahepatic duct may require hepaticojejunostomy

(Left) Axial CECT in a patient who had recently undergone partial hepatectomy demonstrates development of a biloma in the surgical bed.

(Right) Frontal ERCP image in the same patient demonstrates active extravasation of contrast into the biloma from the right hepatic lobe bile duct distribution. Unlike other imaging modalities, ERCP can definitively identify an active bile leak and confirm that a fluid collection represents a biloma.

(Left) Axial CECT in a patient with fever and abdominal pain 21 days after a laparoscopic posterior segment wedge resection of a small hyalinized hemangioma shows a central right lobe biloma and surrounding devascularized, infarcted liver .

(Right) ERCP of the same patient shows a bile leak with spillage of contrast into the biloma, and an appropriately positioned drain . The biloma completely resolved after percutaneous drainage and biliary stent placement.

TERMINOLOGY

Definitions

• Loculated collection of bile within abdomen resulting from bile leak

IMAGING

General Features

• Best diagnostic clue

Loculated fluid collection of simple fluid attenuation in close proximity to liver or biliary tree

• Location

Either intrahepatic or extrahepatic

– Most commonly perihepatic (gallbladder fossa, Morison pouch) and subphrenic

• Size

2-20 cm

• Morphology

Usually encapsulated and rounded

May be lentiform if subcapsular

Imaging Recommendations

• Best imaging tool

CECT or Tc-99m IDA

• Protocol advice

Biliary scintigraphy: Sequential 1-minute acquisition for 60 minutes; static imaging at 2-4 hours and at 24 hours (if required)

Radiographic Findings

• ERCP can delineate site of leakage and presence of aberrant ducts that might change treatment approach

May identify site of leak either within intrahepatic ducts or within extrahepatic bile ducts (e.g., cystic duct, common hepatic duct, or aberrant right hepatic duct)

Can delineate injury to aberrant duct (e.g., aberrant right hepatic duct) that may change management

CT Findings

• Water-attenuation fluid collection within or adjacent to liver with exertion of mass effect on adjacent structures

Usually simple in appearance, but may rarely have internal debris, blood products, etc.

Usually no identifiable capsule or peripheral enhancement

• Subcapsular or intrahepatic biloma may result in adjacent transient hepatic attenuation difference (THAD) during arterial phase imaging (secondary to mass effect and diminished portal venous flow)