Laboratory Findings in ABO-Incompatibility Hemolytic Disease of the Newborn (HDN)

Mother	Fetus	Antibodies
O	A	anti-A; anti-A,B
O	B	anti-B; anti-A,B
O	AB	anti-A; anti-B; anti-A,B
A	AB	anti-B
A	B	anti-B
B	AB	anti-A
B	A	anti-A

 

In most cases the mother is Type O.

 

Laboratory findings:

(1) positive direct antiglobulin test (DAT) on the neonate's red blood cells

(2) usually a negative antibody screen on the mother's serum

(3) difference in ABO type between mother and infant according to table above

 

An elution can be performed but often is not necessary. If there is a question of another alloantibody then it may be necessary.

 

Usually the DAT test is only weakly positive and there is no sign of hemolytic disease in the infant. If the mother has a higher titer of IgG antibody then the baby may show some degree of anemia, hyperbilirubinemia and jaundice.