A JAUNDICED NEONATE
History
Armstrong is a 4-day-old Afro-Caribbean infant who is referred by his midwife to the paediatric day unit because of jaundice. His mother thinks that the jaundice may have commenced within the first 24 hours of life, but she was told by the first midwife that she saw that the baby was fine. The child has also been a little sleepy and has not breast-fed as well as previously. His birth weight was 3.70 kg at term. His mother had a splenectomy after falling off a horse as a teenager. This is her first pregnancy. There is no family history of jaundice.
Examination
The sclera are markedly yellow and the infant is somewhat lethargic. He is well perfused and apyrexial. There is no hepatosplenomegaly and there are no other signs. He weighs 3.40 kg.
INVESTIGATIONS
Normal
Haemoglobin 12.1 g/dL 14.0–22.0 g/dL
White cell count 27.7 109/L 9.0–30.0 109/L
Platelets 361 109/L 150–400 109/L
Reticulocytes 12 per cent 2 per cent
Blood film Occasional spherocytes
Sodium 143 mmol/L 135–145 mmol/L
Potassium 5.0 mmol/L 3.5–5.0 mmol/L
Urea 6.2 mmol/L 1.1–4.3 mmol/L
Creatinine 110 mol/L 27–88 mol/L
Bilirubin 560 mol/L 205 mol/L
Albumin 30 g/L 25–34 g/L
Alanine aminotransferase 48 U/L 6–50 U/L
Alkaline phosphatase 367 U/L 145–420 U/L
C-reactive protein 5 mg/L 6 mg/L
Baby’s blood group A
Maternal blood group O
Direct antiglobulin test (DAT) Positive
Glucose-6-phosphate
dehydrogenase (G6PD) 7.4 IU/g Hb 4.6–13.5 IU/g Hb
Urine dipstick No leucocytes or nitrites
Questions
• What are the causes of jaundice in a neonate?
• Why is neonatal jaundice potentially dangerous?
• What is the cause in this infant?
• What is the treatment?
Medicine
The causes of jaundice are best considered by dividing jaundice into early-onset, normalonset and late-onset jaundice.
Causes of jaundice
Early onset (first 24 hours, haemolytic jaundice)
• Rhesus haemolytic disease
• ABO incompatibility
• G6PD deficiency (commonest in those of African, Asian, or Mediterranean descent)
• Hereditary spherocytosis Normal onset
• Physiological (all newborns get a degree of jaundice peaking at 4–5 days)
• Bruising
• Polycythaemia
• Causes of early jaundice Late onset (14 days, prolonged jaundice)
• Persistence of a pathological earlier jaundice
• Breast milk jaundice
• Neonatal hepatitis
• Biliary atresia
• Hypothyroidism
• Galactosaemia
Jaundice can also be a non-specific marker of neonatal infection at any stage. Neonatal jaundice can be dangerous, as unconjugated bilirubin can cross the blood–brain barrier. Very high levels can lead to kernicterus which can cause deafness and choreoathetoid cerebral palsy. The cause of the jaundice in this infant is ABO incompatibility. His mother is O and will therefore have anti-A and anti-B antibodies in her blood. Theses antibodies can cross the placenta and lead to haemolysis in infants with either blood group A or B. This is further confirmed by the positive DAT (though, on occasion, this test can be negative). The decreased haemoglobin and raised reticulocyte count provide further evidence of haemolysis. The presence of a few spherocytes is common in ABO incompatibility. The normal temperature, normal inflammatory markers and normal urine dipstick make infection unlikely. Unlike Rhesus haemolytic disease, it can occur with the first pregnancy and does not get worse with successive pregnancies. There are graphs that provide guidelines stating at what bilirubin level treatment with phototherapy and an exchange transfusion are indicated. The guidelines depend on the age of the infant, their weight, gestation and on whether they are well or ill. This infant’s bilirubin level is well above the exchange transfusion line. Phototherapy should be commenced immediately and blood taken for cross-match (for O blood to minimize further haemolysis). The fall in birth weight of 8 per cent and the raised urea and creatinine suggest a degree of dehydration which could be exacerbating the jaundice.
Maintenance intravenous fluids should therefore be commenced and breast-feeding can be continued. Appropriate lines should be inserted to enable the exchange transfusion to take place. The blood for the transfusion usually has to be ordered from the regional blood transfusion centre. It is possible that the bilirubin will have fallen markedly by the time the blood has arrived, in which case the exchange transfusion may be avoided. Following discharge, the haemoglobin should be monitored, a hearing test arranged and development followed up.
KEY POINTS
• Neonatal jaundice is a potential cause of kernicterus that can lead to deafness and cerebral palsy.
• Jaundice may be more difficult to diagnose in Asian and Afro-Caribbean babies.
• Treatment in severe cases consists of phototherapy an exchange transfusion.
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