A neonate with Rh haemolytic disease has rapidly rising unconjugated bilirubin despite phototherapy, approaching exchange transfusion thresholds. Which single complication does untreated severe hyperbilirubinaemia risk?

Answer: B. Kernicterus (bilirubin encephalopathy)

Kernicterus

In haemolytic disease of the newborn, ongoing haemolysis releases unconjugated bilirubin, which can rise rapidly after birth (the placenta no longer clears it).

The risk

• Very high unconjugated bilirubin can cross the blood-brain barrier and deposit in the basal ganglia, causing kernicterus (acute and chronic bilirubin encephalopathy).
• Features include lethargy, hypotonia then hypertonia, a high-pitched cry, seizures, and long-term choreoathetoid cerebral palsy, deafness and gaze palsy.

Management to prevent it

• Phototherapy to lower bilirubin.
• Exchange transfusion when bilirubin approaches neurotoxic thresholds (also corrects anaemia and removes antibody-coated cells).

Preventing kernicterus is the goal of neonatal bilirubin management in HDFN.