Biliary Ascariasis

Tummy Ache
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Diagnosis and reasoning

This middle aged gentleman has presented with right hypochondriac pain of acute onset, in association with a swinging fever and jaundice. This is the classical 'Charcot's triad' of acute cholangitis - and this should be presumed to be a case of such until proven otherwise. That said, while Charcot's triad has a high specificity for acute cholangitis, there are a few other conditions for which it may yield a false positive result - most prominently, acute cholecystitis and acute pancreatitis. Regardless of the actual underlying condition, what matters immediately is that this patient is acutely, severely ill - note in particular the tachycardia and blood pressure which is towards the lower limit of normal. He should immediately be moved to a setting where close monitoring is possible; a nasogastric (NG) tube should be placed in situ, IV fluids, electrolytes and broad spectrum antibiotics commenced, and an appropriate analgesic administered. Once he is stabilized (and indeed, during the process of stabilization) the underlying condition can be evaluated in further detail. Jaundice is uncommon in early acute cholecystitis; however, this may occur if there is concomitant choledocholithiasis or Mirizzi syndrome. His examination is mainly remarkable for right-upper quadrant tenderness; unfortunately, this sign may be encountered in all of the above conditions. However, note the absence of Murphy's sign; in the non-elderly, this has an estimated sensitivity of 97.2% for detection of acute cholecystitis, making this diagnosis unlikely. His basic investigations also prove to be useful - note that both serum amylase and lipase are within normal parameters. In an episode of acute pancreatitis of this severity, one would expect a significant elevation. An exception to this rule would be an episode of acute-on-chronic pancreatitis (where the pancreas is already damaged and depleted of enzymes). However, there is no history that would suggest this. Note also the presence of marked direct (conjugated) hyperbilirubinemia and elevated alkaline phosphatase. In the context of this patient, this hints at obstruction of the biliary tract. However, this can occur in both acute cholecystitis secondary to an obstruction, as well as in acute cholangitis. Imaging of the biliary tract via ultrasound is probably a good next step; this shows that the gallbladder is contracted with no signs of inflammation, definitively excluding acute cholecystitis. Even more interestingly, the ultrasound scan shows a hyperechogenic tubular structure obstructing the common bile duct (CBD), which is massively dilated (note that the normal diameter of the CBD is < 5 mm in normal individuals, and < 11 mm in individuals in whom the CBD has been instrumented earlier). This sonographic appearance raises the possibility of a very unusual diagnosis: could this be biliary ascariasis ? This is compatible with the history of travel to India, where A. lumbricoides is endemic. Further imaging of the biliary tract via endoscopic ultrasound is a good follow up technique. This demonstrates a roundworm in the CBD, clinching the diagnosis. Endoscopic retrograde cholangiopancreatography (ERCP) should be considered to extract the parasite from the CBD. During ERCP, it would also be wise to obtain a sample of bile for culture and antibiotic sensitivity testing (ABST), to enable guided antibiotic therapy. Anthelmintics should not be administered acutely, as this may result in the worm migrating further in (or the worms in the duodenum migrating into the biliary tree). In addition, death of the worm in the biliary tree may result in a severe inflammatory reaction.


Discussion

Biliary ascariasis (BA) is a rare but dreaded complication of infection with Ascaris lumbricoides. While mainly endemic in Africa, Eastern Asia, Latin America and Southeast Asia, the incidence in the western world is rising due to migration. The adult A. lumbricoides worm generally resides in the jejunum and ileum. However, it may migrate to ectopic sites such as the biliary tree, pancreatic ducts, lungs or urinary bladder in response to external stimuli (such as fever, Anthelmintic drugs, or bowel manipulation during surgery). BA accounts for between 10% to 19% of ascaris-related hospital admissions. Women (especially during pregnancy) are more commonly affected than men (3:1); children much less so than adults. This is probably due to the narrower bile ducts in children hindering worm migration. The disease mainly presents as either biliary colic and acalculous cholecystitis; less often, acute cholangitis, acute pancreatitis and hepatic abscess formation may result. Choledocholithiasis, strictures and cholangiocarcinoma of the CBD are rare, but well documented clinical presentations of BA. Persistent biliary obstruction may in turn lead to ascending cholangitis and recurrent pyogenic cholangitis with detrimental effects. Note that previous cholecystectomy, sphincterotomy or prolonged fasting have been reported as predisposing factors for recurrent infection. Ultrasonography of the abdomen is the most informative imaging modality in the initial assessment; unfortunately, the sensitivity is operator dependent, varying from 25% to 91%. Worms in the biliary tree appear as tubular, motile, echogenic structures. As of present, the role of other imaging modalities such as CT or MRI remains unclear. ERCP is also an important diagnostic technique; when used in conjunction with endoscopic ultrasound, the sensitivity approaches 100%. Cholangiography may show a dilated CBD, motile filling defects within the biliary tree, and irregularity or stricturing of the ductal walls. The worms themselves are seen as long smooth linear filling defects, parallel filling defects and as curves and loops crossing the hepatic ducts transversely. On occasion the worms may be seen lying in the duodenum or across the papillary opening. Serum Alkaline Phosphatase (ALP), Gamma-glutamyl transpeptidase (GGT) and bilirubin are often elevated owing to biliary obstruction. Note that ALP increases earliest, and is the most frequently elevated parameter. Serum amylase and lipase may be raised if acute pancreatitis is associated. There are multiple approaches to the management of BA: 1. Conservative management 2. Endoscopic management 3. Medical techniques 4. Surgical techniques Conservative management suffices in most patients, as worms often spontaneously migrate out of the biliary tract. This should include cessation of oral feeds, IV fluids, antispasmodics, and appropriate analgesia. During this time, the worm should be tracked via ultrasonography. In most cases, if the worm has not migrated after 3 days, conservative management should be considered as failed; as it should be if the patient's condition worsens at any point. In patients in whom conservative therapy has failed, or is inappropriate, endoscopic or surgical therapy is indicated. Endotherapy is recommended even in the presence of pyogenic cholangitis or acute pancreatitis; Dormia basket extraction and ERCP are the main options available. Note that the presence of stones or strictures is another indication for ERCP. Sphincterotomy and balloon extraction should be avoided as much as possible, as this may facilitate re-invasion later. Endotherapy becomes difficult when intrahepatic or pancreatic ducts are involved; these patients correspondingly carry a poorer prognosis. Vermifuge via oral anthelmintics such as mebendazole or pyrantel pamoate is highly effective once it is verified that the worm has moved out of the biliary tract. Note that direct instillation of medications into the biliary tree is contraindicated, as this results in a severe inflammatory reaction elicited by the macerated carcasses of the dead worms. Surgical treatment is generally reserved for the most complicated of cases, which consist of less than 1% of the treatment spectrum. Indications include failed endotherapy, hepatic-ductal or gallbladder ascariasis and acute pancreatitis.


Take home messages

  1. Biliary ascariasis is increasing in incidence in the developed world due to migration.
  2. Ultrasonography is the most informative initial imaging modality, but is operator dependent.
  3. Most cases can be managed conservatively; many others are manageable via endoscopy.

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