Biliary tract is an uncommon site for infestation by Ascaris lumbricoides (round worm). In India biliary ascariasis is highly prevalent in Kashmir valley because of climatic and soil conditions.1-3 Only sporadic reports in the form of anecdotal cases or small patient series have been reported from remaining parts of the country.4-7 In this report we present our experience of this entity, highlighting the possible predisposing factors, clinical features and management.

Methods

All the patients with a diagnosis of biliary ascariasis were analyzed from a prospectively managed database of all cases admitted between April 2004 and April 2010. The diagnosis was made on the basis of ultrasound and/or cholangiographic findings and confirmed by detection of live worm in the bile duct or descending duodenum (in the vicinity of ampulla of Vater). The clinical features, laboratory parameters and treatment of these patients were reviewed.

Results

A total of nine (two males and seven females) patients were included in this study. The median age was 62 yrs (range 37 - 68 yrs). Six patients had prior cholecystectomy for symptomatic cholelithiasis. Two of these patients had concomitant choledocholithiasis that was treated with choledocholithotomy and T tube drainage in one and lateral choledochoduodenostomy (CDD) in another. The T tube cholangiogram showed a retained stone in the common bile duct (CBD) for which the patient was referred to our center for endoscopic extraction. The remaining four patients at a later date were detected to have retained CBD stones that were treated by endoscopic sphincterotomy (ES) and stone extraction. The median interval between diagnosis of biliary ascariasis and sphincter ablative/ bypass procedure (ES or CDD) was 14 months (range 6 months – 4 yrs). Three patients presented without any prior history of biliary symptoms or surgery. All but one patient presented with acute onset pain abdomen predominantly located in the upper abdomen and very typically radiating to back. The patients variously described the pain as piercing, cutting or hammering in character. Clinically the pain appeared to mimic a pancreatic pathology except that it had a waxing and waning character with minimal abdominal signs. The median duration of symptom was 24 hrs (range 6 hr - 3 days). The patient with T Tube choledochostomy who was otherwise asymptomatic had an incidental detection of a worm on cholangiogram prior to endoscopic extraction of the retained stone. All the patients were anicteric and afebrile. Examination of the abdomen revealed mild epigastric tenderness in five patients. One patient with intact gallbladder had positive ‘Murphy’s sign’ suggesting acute cholecystitis. In the remaining patients clinical diagnosis of biliary colic or acute pancreatitis was entertained. Laboratory investigations showed normal differential and total eukocyte
counts in all cases. The liver function tests (serum bilirubin, aminotransferase, alanine transferase and alkaline phosphatase) were normal except in two patients in whom the liver enzymes showed mild elevation. Serum amylase was normal in all the symptomatic patients. Ultrasound examination of abdomen revealed a dilated CBD in eight patients. A linear echogenic structure suggestive of round worm was reported in the CBD in six of these patients. Features suggestive of acute cholecystitis were present in one patient. All the patients were subjected to endoscopic retrograde cholangiogram (ERC) with a diagnostic and therapeutic intent. In one patient part of the round worm was seen partially projecting out of the papilla of Vater (Figure 1). After extraction of this worm, CBD opacification was performed that showed dilatation but no filling defect. In two patients only dilated CBD was noted but live worm(s) were found in the descending part of duodenum suggesting their possible migration out of the bile duct. In five patients curvilinear filling defects suggestive of round worm(s) were noted in the CBD (Figure 2). In the lone patient with choledochoduodenostomy, a live worm was found across the stoma partly inside the CBD (Figure 3). Attempts were made to harness and extract the worm(s) with a Dormia basket or ‘rat-tooth’ forceps. Failing the above, an endoscopic balloon was employed to extract the worm out of the CBD and once outside the papilla, the worm was grasped with the forceps and extracted successfully. We made sure to deliver all the worms, whether in the bile duct or the duodenum, by withdrawing the endoscope completely and avert any chance of their re-entry. Endoscopic extraction of the worm(s) was
successful in all patients. The patients were subsequently administered albendazole 400 mg daily for three days and mebendazole 200 mg twice daily for three days. After discharge patients were advised to take albendazole 400 mg once every three months. Over a median follow-up of 2 yrs (2 wks - 4 yrs) one patient returned after eight months with recurrence of symptoms. On ultrasound examination she was detected to have round worm re-infestation in her CBD and was confirmed on ERCP and the worm was successfully removed in the same manner as before. Rest of the patients continue to be asymptomatic.

Discussion

In the present report seven out of nine patients were females. A higher prevalence in the female sex has been documented by several other reports as well.[1,4,8] This has been attributed to progesterone induced sphincter of Oddi relaxation promoting migration of worm into the biliary tree.[4] In another report prior sphincterotomy has been attributed as the major cause for biliary ascariasis.[5] In our experience four patients had prior endoscopic sphincterotomy and one had biliary bypass in the form of choledochoduodenostomy. Thus, sphincter ablation emerged as the most important cause in our cohort prompting migration of the worms into the biliary tree.

Pain is the commonest mode of presentation in biliary ascariasis and has been reported in 60-90% patients across various series.[1,2,3,4,8] Though described as biliary colic in these reports, the round worm induced pain in our experience was quite typical and merits further qualification. All but one patient presented with acute onset pain abdomen that mimicked pancreatic pain i.e. acute upper abdominal pain radiating to the back, except that it was waxing and waning in nature with minimal abdominal signs. The serum amylase was normal in these patients thus excluding pancreatitis as the cause of pain. The other presenting features of biliary ascariasis are obstructive jaundice, acute cholangitis, acute cholecystitis, acute pancreatitis and liver abscess.[1,2,3,4,8] Only one patient in our study presented with acute cholecystitis. None of our patients showed any clinical or biochemical evidence of biliary obstruction. This is pertinent since majority of our patients had prior sphincterotomy that did not allow complete obstruction to occur. In addition the movement of a live worm in and out of the CBD resulting in an intermittent obstruction is a well known phenomenon.

Ultrasound examination of abdomen is a reliable screening tool for the diagnosis of biliary ascariasis.[7,9] In our series the presence of round worm in the biliary tree could be detected in all the eight patients who underwent this ultrasound examination. On endoscopy, a worm projecting out of the papilla was noted in one of our patients and offered a definitive confirmation of the diagnosis. On ERC linear or curvilinear filling defects in the biliary tree confirm ultrasound findings and the diagnosis of biliary ascariasis. However in cases with positive ultrasound findings but lack of a filling defect in the cholangiogram the diagnosis may be explained by the presence of a live worm in the vicinity of papilla since they are known to move back and forth in the CBD.

Conservative treatment and oral antihelminthics have been found to be successful in more than 80% of patients with biliary ascariasis.[2,10,11] Some authors, however, recommend early intervention to ward off complications.[1,3,8] Surgical intervention can be undertaken in the form of cholecystectomy and/or CBD exploration with complete removal of the worms.[2,3] Synchronous enterotomy and worm extraction has also been performed to ward off re-infection. When facilities are available endoscopic extraction of the worms appear to be a better alternative and gives prompt relief.[1,4,5,8,9] Endoscopic extraction was successful in all our patients and provided a prompt relief to the agonizing pain they were suffering from. Re-infection was noted in one of our patients. This is similar to the experience reported by other authors.[12] To minimize the problem of recurrence, they recommend endoscopic balloon sphincteroplasty instead of conventional sphincterotomy prior to worm extraction from CBD. Though we concur with the authors on this issue, we did not have the opportunity to employ this in our patients.

Conclusion

Biliary ascariasis, though uncommon in non-endemic area, should be considered in the diagnosis of acute abdomen. This is particularly true in patients who have undergone prior biliary sphincter ablation/ bypass procedures like sphincterotomy or choledochoduodenostomy. Pain could be the only presenting feature and is often out of proportions to the abdominal signs. Ultrasound is a reliable screening test for diagnosis and ERC provides confirmation. Once diagnosed, endoscopic extraction of the worm is often successful and provides prompt relief to the patient. Antihelminthics should be administered for eradication of worms from the intestine and to prevent their reentry into the biliary tree.

References