Biliary ascariasis: the value of ultrasound in the diagnosis and management

Abstract

Background: Conventional methods of radiographic examination are often unsatisfactory for identifying worms in the biliary tract. Ultrasonography is a non-invasive, quick and safe procedure known to have diagnostic accuracy. We studied the ultrasonographic appearances of biliary ascariasis and the role of ultrasonography in diagnosis and management.

Methods: In a prospective 5-year study, a sonographic diagnosis of biliary ascariasis was made on 46 Yemeni patients. The diagnosis was based mainly on sonographic appearances supported by clinical and laboratory results and proved by outcome of either surgical or medical management or spontaneous exit of worms. Follow-up ultrasound was performed for all patients to confirm the diagnosis and to monitor management.

Results: Parasites were present in the dilated main bile duct in 23 patients, in the gallbladder in 12 patients, in the intrahepatic ducts in 6 patients, in the main pancreatic duct in 4 patients and as an intrahepatic abscess in one patient. The characteristic appearance of Ascaris lumbricoides was as single or multiple echogenic non- shadowing linear or curved strips with or without echoic tubular central lines that represent the digestive tracts of the worm. A spaghetti-like appearance was seen in 9 patients and amorphous fragments were seen in 2 patients. Sixteen patients underwent surgery, 20 patients were treated medically (including spontaneous exit of the worm in 7 patients without treatment) and in 10 patients worms were extracted by endoscopic retrograde cholangiopancreatography.

Conclusions: Follow-up ultrasound was found to be effective in confirming the diagnosis and monitoring management.

Figure 1

An oblique ultrasound scan of a 25-year-old female patient demonstrating fusiform expansion of the common bile duct (at surgery proved to be a choledochal cyst), which contains a rather large shadowing stone with an associated echogenic non-shadowing tubular structure (with anechoic linear center) proximal to the stone (arrow) and extending to the common hepatic duct.

Figure 2

Another female patient aged 16 years with fusiform expansion of the common bile duct containing a non-shadowing, echogenic tubular structure with an anechoic linear center that showed active movement during examination.

Figure 3a

Longitudinal ultrasound section of a relatively distended gallbladder containing a long echogenic, non-shadowing intraluminal tubular structure with a central anechoic linear area (the “inner tube” sign), representing the digestive tract of the worm.

Figure 3b

Follow-up of Figure 3a shows change in configuration of the previously seen worm with the appearance of an additional smaller one posterior to it.

Figure 4a

Ultrasound scan of a gallbladder of another patient showing two intralumenal worms.

Figure 4b

Change in the configuration and positioning of the worm seen in Figure 4a on the control ultrasound, confirming the diagnosis.

Figure 5a

A longitudinal section of gallbladder with the worm represented as an echogenic, non-shadowing tube-like structure (strip sign).

Figure 5b

Change in configuration of the worm in Figure 5a. with the worm folded on itself on the control scan, confirming the diagnosis.

Figure 6

A longitudinal scan of a relatively contracted gallbladder showing several non-shadowing, overlapped, tube-like worms (“spaghetti” sign).

Figure 7a

In this patient, the gallbladder shows short non-shadowing hyperchoic curved strips that become ring-like in Figure 7b.

Figure 7b

The curved strips in Figure 7a have become ring-like.

Figure 8

A longitudinal section of the gallbladder of a 15-year-old female patient shows a comma-shaped worm that exhibits active movement during ultrasound examination.

Figure 9a

A transverse scan through the left hepatic lobe shows a dilated intrahepatic duct that is packed with worms, producing an amorphous appearance and some worms in the form of a bolus.

Figure 9b

Another transverse scan through the left hepatic lobe showing a dilated intrahepatic duct packed with worms in the form of a bolus.

Figure 10

An ultrasound scan through the pancreas showing a worm bolus in the proximal segment of the dilated pancreatic duct.