A 24-year-old woman was admitted with 3 days of colisky right upper-quadrant pain radiating to the back.
Ashwin Garg, DMRD, DNB
Vijay Hanchate, MD
Soni Chawala, MBBS
Preeti Sangle, MBBS
, Department of Radiology, Seth GS Medical College and KEM
Hospital, Mumbai, India.
A 24-year-old woman was admitted with 3 days of colicky right
upper-quadrant pain radiating to the back. She had no jaundice or
previous episode of symptoms. Her last menstrual period was 4
months previously. Physical examination was normal. Ultrasonography
of the pelvis and abdomen were ordered.
Sonography of the pelvis revealed a live intrauterine fetus.
Abdominal sonography showed a dilated common bile duct (CBD) up to
its distal portion with long nonshadowing echogenic strip running
the length of main bile duct (Figure 1). Bowel loops were
distended; the gallbladder was enlarged with thickened walls and
showed echogenic sludge within the lumen. The gallbladder also
showed an echogenic, nonshadowing tubular structure with an
anechoic tube inside (Figure 2). Collection was also seen around
the bladder. The patient was asked to wait for some time to allow
for consultation with a senior physician. During this time, the
patient began to experience additional colicky pain in the right
During this period, the ultrasound examination revealed a
moving, long longitudinal echogenic structure entering the
gallbladder from the bile duct (Figure 3). Later sonography of the
gallbladder showed a longitudinal tubular structure with amorphous
fragments inside (Figure 4). Distended bowel loops also showed a
similar structure with an anechoic inner tube. Based on these
sonographic findings, the diagnosis of ascariasis worm induced
biliary colic with ascariasis cholecystitis was made.
Infestation with Ascaris lumbricoides (roundworm) is the most
common helminthic disease of mankind, and it is highly endemic in
developing tropical and subtropical countries.
Poverty, overcrowding, unhygienic living conditions, use of human
excreta as fertilizer, etc. play an important role in the high
prevalence of ascariasis in these countries. In this case, the
patient had a history of pica eating during the early period of her
present pregnancy. Ascariasis of the gallbladder, unlike that of
the bile duct, is a rare entity. The adult worm lives mainly in the
jejunum. Its radiologic appearances in the bowel are well known.
From there it can move up into the main biliary tract, reaching the
intra-hepatic ducts and the gallbladder. In this situation, it
causes biliary colic and, occasionally, acute cholecystitis.
Ascending cholangitis and hepatic abscesses are uncommon
If they are trapped in the ducts and die, they form a nidus of
stones. The high glucoronidase activity of worms and of
deconjugates biliribin and helps to form pigment stones.
Endoscopic retrograde cholangiopancreatography is an excellent
diagnostic tool. It also has a major therapeutic role, as it is
possible to perform the endoscopic extraction of the worm across
However, this procedure has limitations; it must be done during
active biliary symptoms, is cost-prohibitive, and is technically
Ultrasound has been advocated as a highly sensitive and
specific, quick, safe, noninvasive, and relatively inexpensive
modality for suspected biliary ascariasis. Various appearances of
roundworms in the biliary tract and gallbladder have been
It can be used in symptomatic patients and can be repeated
frequently to monitor movement of worms in the ducts or exit from
the ducts. The reported sonographic appearances of roundworm
1) "Stripe" sign: A single, long linear or curved echogenic
nonshadowing structure without an inner tube, located within the
CBD or gallbladder (Figure 5).
2) "Inner-tube" sign: A thick, long, linear or curved
nonshadowing echogenic stripe containing either a central anechoic
tube or a tubular structure with amorphous fragments inside in the
gallbladder or CBD. Both of the anechoic tube and the amorphous
fragments likely represent the digestive tract of the worm.
3) "Spaghetti" sign: Multiple, long linear overlapping echogenic
structures due to coiling of a single worm or several worms in the
CBD (Figure 6).
Other sonographic appearances that have been described in
patients with biliary ascariasis include dilatation of the bile
duct, gallbladder distension with edematous wall, and presence of
echogenic sludge within the gallbladder.
False-positive sonographic diagnoses may arise due to vague
linear echoes in the main bile duct due to reverberations from more
anterior tissue interfaces. However, these are not as well-defined
or as longitudinal as the stripe sign of ascariasis.
In contrast to worms, the stones in the biliary tract appear as
high-level echogenic structures with acoustic shadowing. While
stones can also change position within bile ducts, their movement
is related to changes in the posture of the patients.
Ultrasonography is useful in the identification of this parasite
in the biliary tract and can be performed even while the patient is
having symptoms. This case illustrates the ascaris worm moving out
of the bile duct into gallbladder, causing biliary colic. Prior to
the onset of biliary colic, sonography had demonstrated the ascaris
worm in the gallbladder with the features of ascaris cholecystitis.
The images in this article demonstrate the typical morphology and
the movement of the ascaris worm.
This case illustrates the complications of biliary ascariasis
and the role of real-time ultrasound in the evaluation of biliary
ascariasis, since the movement of the worm helps to make the
diagnosis. This case also describes various morphologic appearances
of ascaris worm on sonography.