NEONATAL CONDITIONS
Pathological Jaundice
A practical guide for SCN clinical staff · When newborn jaundice signals disease, not just immaturity
PATHOLOGICAL
UNTIL PROVEN
Increased bilirubin load
Haemolysis or extravasated blood (cephalhaematoma, bruising) produces bilirubin faster than the newborn can conjugate it.
Immature conjugation
Low UGT1A1 activity, worsened in some babies by breast-milk factors, limits hepatic conjugation so unconjugated bilirubin accumulates.
Enterohepatic recycling
Poor feeding and slow gut transit increase reabsorption of bilirubin from the gut back into the circulation.
Free bilirubin and the brain
Unbound (free) unconjugated bilirubin crosses the blood-brain barrier; sepsis, acidosis, prematurity and low albumin raise free bilirubin and lower the safe threshold.
Conjugated (obstructive)
A conjugated rise means impaired bile flow (biliary atresia, neonatal hepatitis, infection, metabolic) - a different and urgent problem.
CLINICAL FINDINGS
- Jaundice appearing in the first 24 hours of life
- Cephalocaudal spread; assess in natural light with the skin blanched
- Pallor, hepatosplenomegaly, bruising or a cephalhaematoma (haemolysis or extravasation)
- Signs of sepsis - temperature instability, poor feeding, lethargy
- Encephalopathy: lethargy then hypertonia, retrocollis/opisthotonus, a high-pitched cry
INVESTIGATIONS
- Serum bilirubin (total + conjugated) on an hour-specific nomogram - the key test
- Blood group (mother and baby) and DAT (Coombs)
- FBC, blood film and reticulocytes for haemolysis
- G6PD assay; consider spherocytosis
- Sepsis screen if unwell; work up any conjugated fraction
- Avoid the transcutaneous meter if <24h or already on phototherapy
RED FLAGS
- Jaundice <24h is pathological until proven otherwise (haemolysis or sepsis)
- A rapidly rising bilirubin crossing nomogram lines
- A level at or near the exchange threshold
- Any conjugated hyperbilirubinaemia - never physiological
- Signs of encephalopathy are a neurological emergency
THE HAEMOLYTIC CAUSES
Most pathological unconjugated jaundice is haemolytic. The direct antiglobulin test (DAT) and the blood film sort immune from non-immune causes - start there.
ABO incompatibility
Mother group O, baby A or B; maternal anti-A/anti-B IgG crosses the placenta.
The commonest haemolytic cause; can occur in a first pregnancyDAT is often weak or negative; spherocytes on the filmUsually phototherapy; occasionally IVIG or exchange - watch for later anaemiaRhesus (RhD) disease
An RhD-negative mother sensitised to an RhD-positive baby; maternal anti-D IgG drives brisk haemolysis.
Now uncommon thanks to anti-D prophylaxis, but can be severe - hydrops, anaemia, early rapid jaundiceDAT is strongly positive; anticipate it from the antenatal antibody screenPhototherapy, IVIG and exchange; monitor for late anaemia needing top-up transfusionsOther red-cell antibodies
Anti-c, anti-E, anti-Kell and others cause haemolytic disease of the newborn; Kell also suppresses red-cell production.
Flagged on the maternal antibody screen; severity variesTreat as for Rh diseaseInvolve the team early when known antenatallyHereditary spherocytosis
An inherited red-cell membrane defect (often a positive family history); spherocytes are cleared early.
Spherocytes on film with a NEGATIVE DAT - this distinguishes it from ABOAnaemia and splenomegaly; EMA binding or osmotic fragility confirmsTreat the jaundice; later folate and watch for anaemia and aplastic crisesG6PD deficiency
An X-linked enzyme defect (commonest in males of Mediterranean, African, Asian and Middle Eastern background); oxidative haemolysis.
Can cause severe neonatal jaundice, often without an obvious triggerThe assay can read falsely normal during brisk haemolysis - repeat later if suspectedTreat the jaundice; avoid oxidant drugs and naphthalene (mothballs)Other causes to remember
Not all haemolysis is immune, and not all pathological jaundice is haemolytic.
Non-immune load: polycythaemia, extravasated blood (cephalhaematoma, bruising), sepsisRarer defects: pyruvate kinase deficiency, elliptocytosisA conjugated rise points away from haemolysis to a liver or obstructive causeMANAGEMENT
Plot the level, treat to threshold with phototherapy, find and treat the cause, and act early on a rising or very high bilirubin to prevent kernicterus.
Phototherapy
- Plot bilirubin against age in hours and treat at the threshold
- Intensive phototherapy: maximise skin exposure, eye protection, keep hydration and feeds
- Recheck the level 4-6h after starting, then follow the trend
- Feeding plus phototherapy reduces enterohepatic recycling
Escalation / exchange
- Exchange transfusion at or above the exchange line, or with encephalopathy
- IVIG for isoimmune haemolysis (Rh/ABO) with a rising level despite phototherapy
- Prepare for exchange while arranging retrieval
- Correct acidosis, hypoxia and dehydration - they lower the safe threshold
Find the cause
- Blood group and DAT, film, reticulocytes, G6PD
- Sepsis screen; treat sepsis and dehydration
- Split the bilirubin - a conjugated fraction needs its own urgent work-up
- Review maternal blood group and antibody status
Escalate
- Discuss with NICU / NETS early for high or rapidly rising levels
- Any baby needing exchange, or showing neurological signs, is an emergency
- Give parents clear safety-net advice on feeding and review
What makes jaundice in the first 24 hours an emergency?
How do you use an hour-specific nomogram to choose phototherapy vs exchange?
Which investigations sort out the cause of pathological jaundice?
Why do sepsis, acidosis and prematurity lower the safe bilirubin threshold?
Take-home message: Pathological jaundice is jaundice that is too early (<24h), too high, too fast, conjugated, or prolonged. Send a serum bilirubin with a conjugated fraction, plot it on an age-in-hours nomogram, and treat to threshold with phototherapy while you find and treat the cause. Act early on rising or very high levels and escalate - untreated pathological jaundice causes kernicterus.
For educational purposes only. Always align management to current ANZCOR/NRP guidelines and your local SCN/NICU or NETS protocols.