How is neonatal jaundice diagnosed?

In the pathological group, the jaundice occurs within the first 24 hours after birth. The baby may even be jaundiced at birth. The baby may be unwell on examination, have an enlarged liver or spleen, have a rash, have pale stools or be pale. The bilirubin level can be very high, usually more than 275 ìmol/l in haemolytic disease. Jaundice lasting more than two weeks is considered to be prolonged jaundice and requires further investigation.

The majority of jaundiced babies will be managed simply by screening for the total serum bilirubin (TSB). A sample of the baby’s blood is spun down and the colour of the serum is measured in a machine – the darker the serum, the higher the bilirubin level. Most delivery units will be able to do this screen.

The TSB can be checked daily or more frequently if the baby is receiving phototherapy until it shows a downward trend. It may have to be checked three-hourly if one is monitoring haemolytic jaundice.

In some cases it will be necessary to have the exact levels measured by a laboratory and to distinguish between the bilirubin that has been processed by the liver (conjugated bilirubin) and that which is still to be processed (unconjugated bilirubin).

In physiological as well as haemolytic jaundice the unconjugated fraction is much greater than the conjugated, whereas in hepatitis the conjugated is higher (obstructive jaundice). The two fractions added together are the total serum bilirubin or TSB.

Other common tests that may be done are the mother’s blood group and screening for syphilis (an important cause of neonatal jaundice) and the baby’s blood group. In some places a screen for hypothyroidism (also a cause of prolonged jaundice) is done.

Further tests that may be considered if pathological neonatal jaundice is suspected are: checking the baby’s blood for anaemia, a Coomb’s test (screening for antibodies that may be causing haemolysis), assaying for G-6-PD, liver function tests or a screening for important possible neonatal infections (screening the baby for common congenitally acquired infections).