Early diagnosis of ABO haemolytic disease of the newborn.

To assess the usefulness of cord blood tests in diagnosing ABO-haemolytic disease of the newborn (ABO-HDN), 132 term, adequate for gestational age (AGA) neonates were evaluated. The tests studied and their significant results were: quantitative elution test (greater than or equal to 1/16), direct Coombs test (positive), bilirubin concentration (greater than or equal to 4 mg/dl). In none of the 56 O+ newborn infants delivered by O+ women were the results of any test positive. Of the 76 A+ and B+ newborn infants delivered by O+ women, 17 (22%) developed ABO-HDN. When the combined result of any two tests was positive, the sensitivity, the specificity and the positive predictive accuracy for the diagnosis of ABO-HDN was higher than for any one of the isolated tests. The probability that ABO-HDN was present when the results of at least two cord blood tests were positive was 70%, and the probability that ABO-HDN was not present when less than two cord blood tests gave positive results was 93%. It is suggested that the combination of quantitative elution test, bilirubin concentration and direct Coombs test in the cord blood is useful for an early diagnosis of ABO-HDN.