Conjugated jaundice and neonatal cholestasis: Viva

Branch 1: The decision to investigate

The candidate should immediately identify that reassurance without a conjugated bilirubin is unsafe. Jaundice persisting beyond two weeks in a term infant mandates a split bilirubin measurement. Breast-milk jaundice is a diagnosis of unconjugated hyperbilirubinaemia only and cannot be invoked until a conjugated fraction has been measured and found normal. The candidate must ask about stool and urine colour directly, because acholic stools or dark urine would make cholestasis and biliary atresia the leading concern. ^[1]

The conjugated fraction threshold is a conjugated bilirubin above 17 micromol per litre or more than 20 per cent of the total bilirubin. A result in this range confirms cholestasis, which is always pathological and triggers the full diagnostic panel. The candidate should explain that the single most avoidable error in neonatal cholestasis is reassurance without a split bilirubin, because it may delay a Kasai operation into the range where it cannot succeed. ^[1]