A case of missed biliary ascariais: Endoscopic retrograde cholangiography still remains the gold standard.

Sir,

A 50-year-old male presented with a 10-day history of jaundice associated with epigastric pain (Institute of Liver and Biliary Sciences, New Delhi, India, 2011). About six weeks prior to this admission, he had an episode of obstructive jaundice for which he had undergone Endoscopic Retrograde Cholangiopancreatography (ERCP), biliary sphincterotomy, and removal of sludge-like material from the bile duct. His investigations were as follows: Serum bilirubin 8.4 mg/dl, alanin transaminase: 141 IU/L, alkaline phosphatase 204 IU/l, and white blood cell count 9200/mm3. His abdominal ultrasound and magnetic resonance cholangiopancreatography (MRCP) revealed a mildly dilated common bile duct (CBD), without any definite evidence of any obstructive lesion. A repeat ERCP was performed two days after MRCP, which revealed a linear filling defect in the CBD [Figure 1] consistent with Ascaris lumbricoides worm [Figure 2]. The patient improved rapidly after removal of the worm.

Figure 1

MRCP (left panel) showing no definite evidence of a filling defect in the bile duct, while ERCP done within a two-day interval revealed a linear filling defect (right panel) within the common bile duct, suggestive of a worm

Figure 2

Left panels show Ascaris lumbricoides partially coming out of the major ampulla on a side viewing endoscope, and the right panel shows the extracted worm

The ultrasound (US) is the imaging modality of choice for biliary ascariasis.[12] However, the sensitivity of US for detection of a single worm is only 50%.[134] The operator dependency and poor visualization of lower CBD are other limitations of US, for detection of biliary ascariasis. MRCP is very accurate in providing detailed information of the biliary system, without operator-dependency. It shows intraductal ascaris as linear hypointense filling defects.[5] However, in this case, the worm remained undetected by both modalities (US and MRCP). The migration of the worm out of the CBD remains a possibility; however, with progressive worsening of symptoms, this is questionable. The easy detection and removal of the worm by ERCP suggests that it is still the gold standard for this condition. Biliary sphincterotomy is frequently performed during ERCP,[6] and it is considered to be a risk factor for biliary ascariasis. It is well-known that MRCP has a poorer resolution than ERCP, and it can miss certain lesions like small stones, small ampullary tumor, and strictures. However, whether it can miss a large worm has not been reported.