Biliary Ascariasis

Clinical History

A 52-year-old man presented at our emergency department with jaundice and diffuse abdominal pain. Blood investigations revealed raised hepatic transaminases, ALP and direct and indirect bilirubin and levels.

Imaging Findings

Abdominal ultrasound evaluation exam was requested and revealed dilatation of intrahepatic and extrahepatic bile ducts (figure 1). The gallbladder was distended, with long hyperechoic structures inside, with hypoechoic centre lines, without posterior acoustic shadowing, creating a tubular coiled appearance. There was no thickening of the gallbladder wall, neither pericholecystic fluid (figure 2). The imaging findings were compatible with biliary ascariasis. After 8-days of oral anthelminthic, ultrasound revealed no dilatation of the biliary three and no endoluminal content inside the gallbladder (figure 3).

Discussion

Ascariasis is the most common helminthic infection worldwide, affecting 25-33% of the population [1;2]. It is endemic in developing tropical and subtropical countries [3].
The adult worm is usually 15–30cm long and 3–6mm thick. Human small intestine is the permanent host [3]. After ingestion of infected eggs, larvae are released in the duodenum and pass through the duodenal wall to the bloodstream. In the lung, they infiltrate in the alveoli, migrate over the bronchial three and trachea, are swallowed and fixed in the jejunum [1;2;4].
In the presence of high overload of worm infestation or other condition that affect the small intestine motility, the worm can penetrate the ampulla of Vater and enter in the biliary and pancreatic ducts [1;2]. Presence in the cystic duct and gallbladder is rare, representing approximately 2% of the hepatobiliary ascariasis (HBA) cases [5].
There is a female prevalence (3:1) and prior biliary surgery, pregnancy and factors that alter the environment around the worm can predispose to HBA [2].
Usually presents in mid-thirties with biliary colic, acute cholangitis, acute cholecystitis, pancreatitis, hepatic abscess, and, rarely, with hemobilia [2;4].
Ultrasound findings include a long, coiled echogenic structure, without posterior shadowing, an echogenic strip with central anechoic line, a gallbladder with a septate appearance caused by an echogenic structure, associated with random movements of these structures [5].
Endoscopic retrograde cholangiograms (ERCP) and MR cholangiograms show intraductal worms as long tubular filling defects in the bile duct or gallbladder [4].
HBA usually resolves after conservative treatment with oral anthelminthic. When conservative treatment fails to eradicate the infection, or the worms are dead or intrahepatic or there are concomitant biliary stones, ERCP and/or surgery are the treatments of choice. Gallbladder ascariasis usually requires cholecystectomy [6].

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Differential Diagnosis List

Final Diagnosis

Biliary ascariasis

URL:	https://eurorad.org/case/16327
DOI:	10.1594/EURORAD/CASE.16327
ISSN:	1563-4086