Prediction of the severity of ABO haemolytic disease of the newborn by cord blood tests.

Seventy-one ABO incompatible (heterospecific) infants and 71 controls, who were free from other potential causes of jaundice, were studied to ascertain which cord blood tests reliably predict the severity of ABO haemolytic disease of the newborn (ABO HDN). The modified Direct Antiglobulin Test (spin DAGT) was positive in all infants who required treatment for haemolytic jaundice and only DAGT positive children showed evidence of impending haemolytic anaemia or compensated haemolysis in cord or capillary blood. Cord serum bilirubin concentration had some predictive value, particularly when the level exceeded 85 mumol/l, but it was a less reliable indicator and had greater value if used in association with the DAGT. The elution test, which is frequently used as a diagnostic tool in ABO HDN, had no predictive value and we felt that its putative value is due to overdiagnosis of ABO HDN in jaundiced heterospecific infants. We conclude that the spin DAGT, despite the weakness of the reaction, reliably identifies infants at risk from severe ABO HDN and is sufficiently sensitive to be used as a single screening test for the early detection of the disorder.