TRAN NGAN CHAU – LE THONG NHAT – HOANG NGUYEN NHAT ANH – PHAN THANH HAI

MEDIC MEDICAL CENTER

ABSTRACT• Purpose To evaluate the role of ultrasound in diagnosing common bile duct (CBD)

ascariasis, confirmed by endoscopic retrograde cholangiopancreatogram and what causes false positive.

• Material and methods A retrospective study was taken on 53 patients at Medic Center from 1999 to 2013.

The patients had acute right subcostal or epigastric pain, diagnosed CBD ascariasis based on ultrasound, confirmed and extracted worm by ERCP.

• Results All the patients underwent abdominal ultrasound detected 2 parallel echogenic

lines in CBD presenting round worm. They continued to be done ERCP for confirmation and treatment. Of 39/53 (73.6%) was revealed Ascaris in CBD ; 8/53 (15%) was admitted with choledocholithiasis whereas 14/53 (26.4% ) was not.

• Discussion and conclusion Ultrasonographic finding of 2 parallel echogenic strips with or without a central

anechoic tube in CBD, Bull’s eye sign or target sign on transversal section and no shadowing might indicate Ascaris in CBD. It played an important role in diagnosing CBD ascariasis. Once diagnosed, ERCP was the first choice for confirmation and treatment. Artifact or worm running away from CBD resulted in false positive.

INTRODUCTION

Ascaris lumbricoides is a common parasite in the tropics that causes obstruction of biliary tract leading to biliary colic, cholangitis, pancreatitis, hepatic abscess, septicemia.

Ultrasound is the initial imaging modality of choice for hepatobiliary disease. Detection of CBD obstructive factors including round worms is common. ERCP then used for confirmation and treatment.

MATERIAL AND METHODS

Between 1999 and 2013, total of 53 patients presenting with an acute right subcostal or epigastric pain were recruited for abdominal ultrasound detecting CBD ascariasis. These patients then underwent ERCP for confirmation and treatment. Round worm imaging were recognized by using ultrasonography on a 3-5 MHz convex transducer. 

RESULTS

Undergoing ERCP, of the total 53 patients, 39 (73.6%) was revealed Ascaris and 8 (15%) admitted with calculi, whereas 14 (26.4%) was not. Ascaris appeared as two thick parallel echogenic strips with a central anechoic tube in a dilated common bile duct. They were “target” sign in transversal section.

Ultrasound showed 2 thick parallel echogenic strips with central anechoic tube in a dilated CBD

ERCP was performed to confirm CBD ascariasis and remove a male Ascaris with his hook.

CBD Ascariasis and VTQ of Ascaris =0,59m/s

21yo female was done Ultrasound detecting a round worm

ERCP was performed to confirm and extract the Ascacris

DISCUSSION

- Appearance of Ascaris on ultrasound includes parallel echogenic strips, linear or curved, with or without a central anechoic tube represent the digestive tract of the worm (inner-tube sign). They were Bull’s eye sign or target sign in transversal section. If many worms are in CBD, sonography shows spaghetti sign. In our study, almost patients showed thick parallel echogenic lines with a central anechoic tube.

Longitudinal section: inner-tube sign (arrow) Transversal section: target sign (arrow)

- There were 14 cases (26.4%) detected round worms on ultrasound but not found by ERCP. Artifact or worm running away from CBD might result in false positive. Wrong image like Ascaris might be seen in the CBD due to reverberations from the anterior wall. But these echoes are not so well defined or continuously as the strips of Ascaris. It might run away from CBD into hepatic bile duct or crossed into Vater's ampulla and entered the intestine, thus ERCP couldn’t reach and find out the worm.

CONCLUSION

Ultrasound is a useful, rapid and non-invasive imaging but operator-dependent tool in diagnosing CBD ascariasis. Once diagnosed, ERCP should be done to confirm and extract the worm. Using many sections on ultrasound to realize artifact or performing another sonographic scanning after ERCP to find out the worm.