Paediatric Radiology

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Answer : Roundworm in gall bladder

Ascariais is the most common helminthic disease of mankind, and is second only to gall stones as a cause of acute biliary symptoms. The adult worm lives maily in the jejunum, and has a tendency to migrate in the common bile duct (CBD), form where it may enter the gall bladder or intra hepatic bile ducts, giving rise to acute biliary colic or acute cholecystitis. If the worm gets trapped in the ducts and dies, it may form a nidus of stones (high glucoronidase activity of the worm deconjugates bilirubin and helps to form pigment stones).

On USG, they may appear as echogenic, non-shadowing structures in the CBD and/or gall bladder. They may appear as single or multiple strips, coiled structures or amorphous fragments, and may have a hypoechoic inner-tubular structure representing the digestive tract. Writhing movements of a live worm may be seen on USG, while a multiplicity of worms may give rise to the so-called spaghetti sign. ERCP may be used to extract worms from the CBD, particularly in patients with acute pyogenic cholangitis or troublesome biliary colic; serial ultrasounds can be used to check worm clearance from the biliary tract.