[Neonatal ABO incompatibility underlies a potentially severe hemolytic disease of the newborn and requires adequate care].

ABO allo-immunization is the most frequent hemolytic disease of the newborn and ABO incompatibility is present in 15-25 % of pregnancies. True ABO alloimmunization occurs in approximately one out of 150 births. Intensity is generally lower than in RhD allo-immunization. We report on three cases showing that ABO allo-immunization can lead to severe hemolytic disease of the newborn with potentially threatening hyperbilirubinemia and complications. Early diagnosis and adequate care are necessary to prevent complications in ABO incompatibility. A direct antiglobulin test is the cornerstone of diagnosis and should be performed at birth on cord blood sampling in all group infants born to O mothers, especially if of African origin. Risk factor analysis and attentive clinical monitoring during the first days of life are essential. Vigilance is even more important for infants discharged before the age of 72 h. Every newborn should be assessed for the risk of developing severe hyperbilirubinemia and should be examined by a qualified healthcare professional in the first days of life. Treatment depends on the total serum bilirubin level, which may increase very rapidly in the first 48 h of life in cases of hemolytic disease of the newborn. Phototherapy and, in severe cases, exchange transfusion are used to prevent hyperbilirubinemia encephalopathy. Intravenous immunoglobulins are used to reduce exchange transfusion. Treatments of severe hemolytic disease of the newborn should be provided and performed by trained personnel in neonatal intensive care units.