Key Facts

Neonatal jaundice is the most common condition requiring medical attention in the first 2 weeks of life. While usually benign, failure to identify and treat significant hyperbilirubinaemia can result in kernicterus — a devastating but preventable condition.

Epidemiology

Visible jaundice affects approximately 60% of term and 80% of preterm neonates. Approximately 10% of breastfed neonates are still jaundiced at 1 month. Significant hyperbilirubinaemia requiring treatment occurs in approximately 5-10%. Kernicterus has an incidence of approximately 1 per 100,000 live births in the UK.

Aetiology

Unconjugated (most common):

• Physiological (immature hepatic conjugation + high RBC turnover)
• Haemolytic: ABO incompatibility, Rh disease, G6PD deficiency, spherocytosis
• Breastfeeding jaundice (poor intake → dehydration → reduced bilirubin excretion)
• Breast milk jaundice (substance in breast milk inhibits conjugation — benign, prolonged)
• Polycythaemia, bruising (cephalhaematoma), sepsis

Conjugated (always pathological):

• Biliary atresia (MUST exclude — pale stools, dark urine)
• Neonatal hepatitis, choledochal cyst, alpha-1 antitrypsin deficiency
• Infections: UTI, sepsis, TORCH

Pathophysiology

Unconjugated bilirubin is produced from haem breakdown in the reticuloendothelial system. Neonates produce 2-3× more bilirubin per kg than adults (higher RBC mass, shorter RBC lifespan). Hepatic conjugation (UDP-glucuronosyltransferase) is immature in the first 2 weeks. Unconjugated bilirubin is lipid-soluble and can cross the blood-brain barrier at very high levels, depositing in the basal ganglia and brainstem nuclei (kernicterus).

Clinical Assessment

• Jaundice progresses cephalocaudally (face → trunk → limbs → soles) as levels rise
• Visual assessment is unreliable — always measure bilirubin if concerned
• Assess feeding, weight, hydration, urine/stool output

Timing

• <24 hours: PATHOLOGICAL — haemolysis (ABO, Rh), sepsis, G6PD
• Day 2-5: Physiological peak; may also be pathological if high
• >14 days (term) / >21 days (preterm): Prolonged — investigate

Red Flags

• Jaundice <24 hours — urgent investigation
• Pale/chalky stools + dark urine — biliary atresia (surgical emergency if confirmed)
• Lethargy, poor feeding, high-pitched cry — bilirubin encephalopathy (early kernicterus)
• Opisthotonos, seizures, apnoeas — acute bilirubin encephalopathy (emergency)
• SBR rising >8.5 µmol/L/hr — rapid rise suggesting haemolysis

Bedside

• Transcutaneous bilirubinometry (TcB): Screening tool — if above threshold, confirm with SBR
• SBR (serum bilirubin): Plot on NICE CG98 gestation-specific treatment threshold chart
• Weight: Compare with birth weight — dehydration worsens jaundice
• Stool and urine colour: Pale stools + dark urine → biliary atresia

Bloods

• SBR (total and split): Conjugated bilirubin >25 µmol/L is always pathological
• Blood group and DAT (Coombs test): Mother and baby — if early or severe jaundice
• FBC, reticulocyte count, blood film: Haemolysis (spherocytes, reticulocytosis)
• G6PD assay: If at-risk ethnicity or unexplained jaundice

If Prolonged Jaundice

• Split bilirubin: Conjugated vs unconjugated
• TFTs: Congenital hypothyroidism
• Urine MC&S: UTI screen
• Liver USS: Biliary atresia (absent/abnormal gallbladder), choledochal cyst

Special Tests

• HIDA scan: If biliary atresia suspected (no isotope excretion into gut)
• Liver biopsy: Confirms biliary atresia (portal tract fibrosis, bile duct proliferation)
• Kasai portoenterostomy: Definitive investigation/treatment for biliary atresia (ideally <60 days of life)

Phototherapy

• Indication: SBR above treatment threshold on NICE CG98 gestation-specific chart
• Mechanism: Blue-green light (460-490nm) converts unconjugated bilirubin to water-soluble photoisomers
• Delivery: Overhead phototherapy unit; maximise skin exposure; eye protection
• Monitoring: Repeat SBR at 4-6h; continue until SBR is ≥50 µmol/L below treatment threshold
• Rebound SBR: Check 12-18h after stopping phototherapy

Exchange Transfusion

• Indication: SBR at or approaching exchange transfusion threshold; signs of acute bilirubin encephalopathy
• Procedure: Double-volume exchange (2 × 80mL/kg for term); removes bilirubin and antibodies
• Risks: Electrolyte disturbance, thrombocytopenia, NEC, infection, cardiac arrest

Pharmacological

• IV immunoglobulin (IVIG): For immune haemolytic jaundice (Rh disease, ABO) if bilirubin rising despite phototherapy

Non-pharmacological

• Support breastfeeding: Ensure adequate feeding frequency (8-12 feeds/day); supplement with expressed breast milk or formula if inadequate intake
• Hydration: Ensure adequate fluid intake; IV fluids if not feeding adequately

Referral Criteria

• Jaundice <24h — urgent paediatric assessment
• Conjugated hyperbilirubinaemia — urgent referral to paediatric liver centre
• Biliary atresia — Kasai procedure ideally before 60 days of life
• Kernicterus signs — emergency exchange transfusion

• Physiological jaundice: Completely benign; resolves without treatment
• Phototherapy: Effective in >95% of cases; exchange transfusion rarely needed
• Kernicterus: Devastating — chronic bilirubin encephalopathy causes choreoathetoid cerebral palsy, sensorineural hearing loss, gaze palsy, dental enamel dysplasia
• Biliary atresia: Kasai portoenterostomy successful in ~60% if done before 60 days; ~50% eventually require liver transplant
• ABO/Rh haemolytic disease: Excellent prognosis with appropriate monitoring and treatment

NICE CG98 — Key Recommendations

Prolonged Jaundice Investigation