Which initial investigations should be performed to differentiate biliary atresia from other causes of neonatal cholestasis?

To differentiate biliary atresia from other causes of neonatal cholestasis, initial investigations should include:

• Measurement of conjugated (direct) bilirubin to confirm cholestasis, as elevated conjugated bilirubin suggests hepatobiliary disease rather than unconjugated hyperbilirubinaemia ¹.
• Full blood count to assess for infection or other hematological causes ¹.
• Blood group determination (mother and baby) and direct antiglobulin test (Coombs' test) to exclude hemolytic causes of jaundice ¹.
• Assessment of stool colour for pale, chalky stools and urine colour for dark urine, which are clinical indicators suggestive of biliary atresia ¹.
• Routine metabolic screening including congenital hypothyroidism to exclude metabolic causes of cholestasis ¹.
• Consideration of urine culture if urinary tract infection is suspected ¹.

These investigations help to identify serious liver disease and guide further specialist referral and imaging, such as abdominal ultrasound and hepatobiliary scintigraphy, which are typically performed after initial blood and urine tests ¹.