Experience and discussions on ultrasound findings of CBD ascariasis on 53 cases and ERCP confirmation.

1. TRAN NGAN CHAU – LE THONG NHAT – HOANG NGUYEN NHAT ANH – PHAN THANH HAI
MEDIC MEDICAL CENTER

2. 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.

3. 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.

4. 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.

5. 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.

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

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

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

10. 21yo female was done Ultrasound detecting a round worm

11. ERCP was performed to confirm
and extract the Ascacris

17. 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.

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

19. - 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.

20. 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.