Gallbladder Ascariasis

Ascariasis, the most common helminthic infection is caused by ascaris lumbricoides. Usually the adult worm lives in the small intestine. Rarely it migrates through the papilla of vater and may enter the common bile duct. Presence of Ascaris lumbricoides in gallbladder is rare entity as it is difficult to reach there due to narrow and tortuous cystic duct.
Ascariasis is the most frequent helminthic infection in humans. The causative organism is Ascaris lumbricoides which normally lives in the lumen of small intestine. From the intestine, the worm can invade the bile duct or pancreatic duct but invasion into the gallbladder is quite rare because of the anatomical features of the cystic duct which is narrow and tortuous .
Ascaris lumbricoides has a tendency to migrate through natural body orifices and enter Wirsung's duct and common bile duct through papilla of Vater . The female parasite is more prone to penetrate through the orifices particularly if the previous sphinterotomy or bilioenteric anastomosis was performed . The biliary ascariasis is more common in female. Pregnant women may be more susceptible due to relaxant effect of hormones on the smooth muscle of the bile ducts . The presentation of biliary ascariasis is similar to the cholelithiasis, acute cholecystitis, choledocholithiasis, acute pancreatitis and asending cholangitis .

The ultrasound is diagnostic in biliary ascariasis. They present like linear echogenic image without acoustic shadow in the lumen of gallbladder and CBD . The findings of erratic, non directional, zigzag movements are characteristic of live worm . The gallbladder may be normal or show signs of acute cholecystitis. Dilatation of biliary duct may be present if worm obstructs the CBD. The other method for the diagnosis of biliary ascariasis includes oral cholecystography, intravenous cholangiography and ERCP. All these test are not very diagnostic. Thus ultrasound is quite sensitive in the diagnosis and can also be used for follow up. The presence of ova in stool is not necessary as the infection may be caused by the male worm. The diagnosis is usually suspected if the patient belongs to the endemic area.

Biliary ascariasis has a good response to conservative treatment like bowel rest, antispasmodic and antihelminthic drugs. Worms within the biliary tract are not killed by the antihelminthic drugs. Successful treatment is possible if the worm returns to the small intestine where they are exposed to adequate concentration of drug. The conservative treatment fails usually in the presence of dead worm, concomitant stones or stricture which prevents the returning of worm in the duodenum .

Endoscopic removal of worm treatment has become the treatment of choice for the CBD ascariasis in which the medical management has failed. Sphinterotomy should be avoided as it appears to predispose to recurrent infestation by the worms. Even after endoscopic removal, an antihelminthic drug has to be given. Although biliary ascariasis responds well to medical management but most of the gallbladder ascariasis needs surgical treatment. All patients who do not respond to conservative or endoscopic treatment should be treated with surgery .