Common bile duct parasite

Case contributed by Muhammad Qasim Naeem


A young male patient (past history of recurrent chronic pancreatitis), presented with colicky epigastric pain

Patient Data

Age: 15 years
Gender: Male

There is mild prominence of right and left main hepatic duct and CBD which is measuring approximately 6 mm. There is a curvilinear cylindrical filling defect in the lumen of the CBD extending superiorly and reaching into the right main hepatic duct with maximum width of approximately 3 mm. Findings are compatible with a parasite, specifically a worm.

Mild periportal tracking noted in both lobes of liver, suggesting periportal edema / reactionary inflammatory changes. Significant atrophy noted in pancreatic parenchyma throughout its extent with mild prominence of pancreatic duct, suggesting changes secondary to chronic pancreatitis.

No lesion seen in liver or in kidneys.


Retrospectively performed US.

Double walled linear / cylindrical isoechoic structure that does not cause posterior acoustic shadowing seen within lumen of common bile duct extending to common hepatic duct.

No evidence of biliary tree dilatation.

Case Discussion

Parasites are common in developing nations. Worms usually affect small or large bowel, but extra-intestinal sites can occur. The commonest are round worms (e.g. Ascaris lumbricoides), these are seen as linear filling defects on MRI, and on ultrasound they appear as cylindrical double walled mobile or non-mobile structures. Unless there are numerous worms they usually don't cause biliary obstruction. These findings are present in our patient.

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