It is remarkable how tricky making a diagnosis of biliary atresia can be, even when one has seen the presentation many times. For parents and many providers, one of the pitfalls includes the inability of recognizing acholic stools. To identify biliary atresia, promotion of stool color cards, over the last two decades, has not been very effective. To address this problem, a recent study (S Harpavat et al. JPGN 2016; 62: 799-803) describes the use of direct or conjugated bilirubin measurements in the newborn period. This study was conducted between 2009-2011.
As with previous studies, 35 infants with biliary atresia all had elevated direct bilirubin. In the non-biliary atresia group, 8936 of 9102 infants had direct bilirubin measurements within the laboratory’s reference range. Thus, this study suggests that newborn direct bilirubin has a sensitivity 100% and specificity of 98.2%.
In a related publication, the same group published a letter to the editor (NEJM 2016; 2016; 375: 605-6) that describes a prospective two-stage screening of newborns for biliary atresia. Of 11,636 infants included over a 15-month period, 121 were identified who had direct-bilirubin >95% reference interval in their laboratory. At a median of 14 days, 11 remained abnormal: 2 had biliary atresia. Overall, they state the net sensitivity was 100%, then net specificity of 99.9%, and the positive predictive value was 18.2%.
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