Clinical and Laboratory Characteristics of ABO-Incompatible Hemolytic Disease of the Fetus and Newborn

ABO incompatibility is the most common cause of hemolytic disease of the fetus and newborn (HDFN). We investigated HDFN at our institute and discuss clinical characteristics and considerations during transfusions and laboratory testing.

We reviewed the medical records of newborns with HDFN due to ABO incompatibility over a period of 5 years. Laboratory results such as the ABO blood type of mothers and newborns, direct antiglobulin test, hemoglobin, and total bilirubin were collected. History of transfusion and phototherapy were also taken.

During the 5 years, 275 newborns were diagnosed with HDFN by ABO blood type testing and crossmatching. Group O mothers were predominant, with 259 newborns, followed by B and A types, with 11 and five newborns, respectively. For the newborns, group A was the most common, with 151, followed by group B with 108 and AB with 16 newborns. The most common type of incompatibility was O/A, accounting for 54.9%, followed by O/B, B/AB, and A/AB at 54.9%, 4.0%, and 1.8%, respectively. DAT was conducted on only half of the group O mothers, and among them, 38.5% had positive results. For the 16 newborns of non-O mothers, six underwent DAT, and all were negative. Further, 21.6% and 31.3% of newborns from group O and non-group O mothers received transfusions, and 49.4% and 43.8% received phototherapy, respectively.

Our findings highlight the importance of considering ABO HDFN even in DAT-negative neonates. Reverse typing may provide important diagnostic value, especially in transfusion settings with ABO compatibility with the maternal blood group.