Endoscopic ultrasound of bile duct ascariasis (with video)

A 40‐year‐old male with no significant medical history was admitted to the hospital with yellowish discoloration of eyes, mild right upper quadrant pain, and intermittent fever for last 1 week. Physical examination revealed icterus and hepatomegaly. Laboratory examination showed obstructive jaundice (aspartate transaminase‐230 U/L, alanine transaminase-180 U/L, alkaline phosphatase-370 U/L, and billirubin-3 mg/dL). Ultrasonography abdomen (USG) revealed dilated common bile duct (CBD) (9 mm) with ill‐defined echogenic shadows. Endoscopic ultrasonography (EUS) was performed with a linear echoendoscope (Pentax EG 3830 UT) using Hitachi Avius‐processor at 7.5 MHz frequency for evaluation of echogenic shadow. It revealed linear echogenic mobile shadow coiling in CBD confirming the diagnosis of biliary ascariasis. This linear shadow had two hyperechoic linear echogenic strips on either side of the longitudinal anechoic lumen of the Ascaris [Video 1 and Figure 1]. On side-viewing endoscopy, the worm was visualized partially lying outside the papilla. The worm was extracted with biopsy forceps and identified as Ascaris lumbricoides [Video 1 and Figure 2]. The worm was 9 cm long and creamy white. Subsequently, deworming was done with albendazole. On follow-up visit, the patient was asymptomatic and USG revealed normal CBD. Biliary ascariasis is a common problem in tropical countries. Abdominal USG, which is the first modality for evaluation of such patients, can allow biliary ascariasis to be diagnosed in 85% of cases. The characteristic sonographic features of worms in the CBD are multiple, long, linear, parallel echogenic strips, usually without acoustic shadowing.[1] Both EUS and magnetic resonance cholangiopancreatography are used for evaluation of dilated CBD. However, EUS appears to be an investigation of choice for dilated CBD.[2,3] On EUS, A. lumbricoides appears as long echogenic structure with central anechoic linear defect, without producing shadow effect. It appears as linear echogenic shadow with two hyperechoic linear echogenic strips on either side of the longitudinal anechoic lumen.[4] Endoscopic intervention has become the treatment of choice. Worms visible at the ampulla can be extracted endoscopically with dormia basket or biopsy forceps. Endoscopic retrograde cholangiopancreatography should be performed if a roundworm has migrated or is present inside the bile duct. Sphincterotomy should be avoided for worm extraction because an open biliary sphinctercan lead to recurrence if worm reinfestation occurs.[5]