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 NICE CG98.
• Full blood count to assess for infection or other hematological causes NICE CG98.
• Blood group determination (mother and baby) and direct antiglobulin test (Coombs' test) to exclude hemolytic causes of jaundice NICE CG98.
• Assessment of stool colour for pale, chalky stools and urine colour for dark urine, which are clinical indicators suggestive of biliary atresia NICE CG98.
• Routine metabolic screening including congenital hypothyroidism to exclude metabolic causes of cholestasis NICE CG98.
• Consideration of urine culture if urinary tract infection is suspected NICE CG98.

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 NICE CG98.