Diagnostic Ultrasound - Abdomen and Pelvis

Biloma
Diagnoses: Liver
TERMINOLOGY
• Encapsulated collection of bile outside biliary tree
IMAGING
• Ultrasound
○ Grayscale ultrasound
– Focal collection of fluid within liver or close to biliary
tree, or in gallbladder fossa in patients with recent
cholecystectomy
– Round or oval in shape, usually unilocular, usually no
discernible thin capsule
– Anechoic fluid content suggests fresh biloma
– Debris or septa suggest infected biloma
– May see echogenic foci at periphery related to dips
from recent surgery
○ Color Doppler ultrasound
– No vascularity within lesion
– For infected biloma, there may be increased
vascularity in adjacent tissue
KEY FACTS
• CECT:Well-defined or slightly irregular cystic lesion without
identifiable wall
TOP DIFFERENTIAL DIAGNOSES
• Perihepatic collection/seroma/lymphocele
• Hepatic cyst
• Hepatic abscess
• Intrahepatic hematoma
PATHOLOGY
• Iatrogenic: Laparoscopic cholecystectomy, post liver
transplantation, ERCP or other instrumentation of biliary
tree, liver biopsy
• Post-traumatic: Blunt trauma, motor vehicle accident
• Spontaneous rupture of bile duct
DIAGNOSTIC CHECKLIST
• Consider underlying infection if low-level echoes within
biloma on ultrasound
(Left) Grayscale US shows a
biloma ſt after surgical
removal of a liver mass. Lowlevel
internal echoes st
suggest infected bile.
Peripheral surgical suture with
a ring-down artifact and
clip with posterior shadowing
are seen. (Right)
Transverse color Doppler US of
the liver shows a biloma in
a resection cavity with
peripheral echogenic foci ſt
with posterior ring down,
likely related to surgical clip. A
small amount of internal
debris is seen in the periphery
of the biloma .
(Left) Transverse color
Doppler US of the liver shows
an infected biloma ſt. The
lesion is avascular and
contains gas st that
demonstrates posterior dirty
shadowing . (Right) Delayed
phase CECT shows a round
cystic mass without a
discernible wall ſt containing
internal debris and layering
debris st in the dependent
portion, which suggests
infected biloma.
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