Thanks, good to see the link still works. Might copy and paste it so it doesn't get lost in the future:

Journals > Volume 31, Number 12, December 2002
Biliary ascariasis
Ashwin Garg, DMRD, DNB; Vijay Hanchate, MD; Soni Chawala, MBBS; Preeti Sangle, MBBS
A 24-year-old woman was admitted with 3 days of colisky right upper-quadrant pain radiating to the back.
COMMENTS comments
Share your thoughts.
Post a comment →
Read Comments(0) →

Download PDF
Save
Print
Add RSS

Prepared by 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.

CASE SUMMARY

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.

DIAGNOSIS

Biliary ascariasis

IMAGING FINDINGS

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 upper quadrant.

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.

DISCUSSION

Infestation with Ascaris lumbricoides (roundworm) is the most common helminthic disease of mankind, and it is highly endemic in developing tropical and subtropical countries. 1 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. 4 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 complications. 2,3 If they are trapped in the ducts and die, they form a nidus of stones. The high glucoronidase activity of worms and of E. coli 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 the papilla. 5 However, this procedure has limitations; it must be done during active biliary symptoms, is cost-prohibitive, and is technically difficult.

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 described. 6-8 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 are:

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. 9 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.

CONCLUSION

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.