Biliary Atresia and Cytomegalovirus Infection

The phenomenon of patent biliary tree at birth and subsequent development of biliary atresia later in the neonatal or infantile period has never been documented till date. In that sense, the authors have tried to report this phenomenon for the first time in the world literature. However, there are several caveats in this hypothesis proposed by the authors [1]. Firstly, the diagnosis of patent biliary tree by scintigraphy (case 1) and MRCP (case 2) by authors needs further clarification. It has been shown by us and many others that short of per-operative cholangiogram (the gold standard in the diagnosis of BA) liver biopsy has got the best accuracy in diagnosing biliary atresia [2,3]. The reported accuracy of scintigraphy in diagnosing biliary atresia is 77 to 84.5% which improves with 48 to 72 hours of ursodeoxycholic acid (UDCA) to 91% [4, 5]. Nevertheless, it is nowhere near 100% and the reported negative predictive value of 76% suggests that the scintigraphic documentation of excretion does not rule out biliary atresia [4]. We need to remember before interpreting scintigraphic report that urinary contamination of the abdomen during the procedure, inadequate labelling of radioisotope tracer or avid renal uptake may mimic an excretory HIDA scan. Secondly, documentation of patent biliary tree by MRCP in an infant is also fallacious. MRCP in an infant has technical difficulties. Spatial resolution is poor in small infants, possible movement artefacts and most importantly absent bile flow in a non-dilated biliary system makes interpretation difficult. Diagnostic accuracy of MRCP is 71-82% with reports of both false positive and false negative results [4]. That is why, despite being noninvasive and available in major hospitals across the globe, it has not become a popular investigation for BA. Interestingly, within 15 days of documenting patent biliary tree by MRCP, liver biopsy showed biliary atresia in the second case. That amply supports our view that the diagnosis of BA was missed in both the cases in the first instance as liver biopsy or per-operative cholangiograms were not used in the first go.