How are biliary atresia and neonatal hepatitis distinguished diagnostically?

Biliary atresia: Ultrasound may show atretic or absent gall bladder. Gallbladder is present in 25% of cases. ⁰
Triangular cord sign: Fibrotic remnant of common duct. A hepatobiliary scan indicates no bowel activity 24 hours post injection. (Normally, bowel activity occurs within 24 hours.)

Hepatitis: A hepatobiliary scan shows poor uptake of radionuclide (i.e., the liver is not as dark as usual) and poor excretion (although tracer should be seen eventually in the bowel). If biliary atresia has been present for a long time, there may be liver dysfunction and poor liver uptake, making it difficult to distinguish biliary atresia from hepatitis.