Ultrasound appearances of intra- and extrahepatic biliary ascariasis

Background: To determine the range of ultrasonographic (US) appearances of Ascaris lumbricoides roundworms in the biliary system, their distribution in the intra- and extrahepatic parts of the system, and associated features. Methods: All cases of biliary ascariasis during a 10-year period were reviewed. There were 42 cases in which diagnosis was based on established US criteria, and 2 cases diagnosed surgically in which US had been negative. These 44 cases occurred in 36 patients. Results: In the US-diagnosed cases, worms were present in intrahepatic ducts in 32 cases, in the main duct in 37, and in the gallbladder in eight. In six cases, the liver was lifted off the main portal vein by a bundle of worms obliterating the lumen of the main bile duct. Worms packing and dilating intrahepatic ducts produced pseudotumorous appearances in the liver in four cases and bundlelike appearances in three. Worms were also seen in the pancreatic duct in two cases. Stones in intrahepatic ducts were present in 12 patients. Conclusion: Biliary ascariasis should be searched for inside and outside the liver, The appearances of bundles and boluses are different from those of single worms. Intra-and extrahepatic biliary stones may be present.