ABO incompatibility disease of the

newborn

Afflicts newborns whose mothers are blood type is O, and who have a baby with type A, B, or AB.

In type O mothers, isoantibody is IgG and is capable of crossing the placental membranes

Transplacental transport of maternal isoantibody results in an immune reaction with the A or B antigen on fetal erythrocytes causing hemolysis

ABO incompatibility disease

A1 antigen in the infant◦ Of the major blood group antigens, the A1 antigen

has the greatest risk of symptomatic disease Elevated isohemagglutinins

◦ Antepartum intestinal parasitism or third-trimester immunization with tetanus toxoid or pneumococcal vaccine may stimulate isoantibody titer to A or B antigens.

RISK FACTORS

Birth order is not considered a risk factor. Maternal isoantibody exists naturally and is independent of prior exposure to incompatible fetal blood group antigens. First-born infants have a 40-50% risk for symptomatic disease. Progressive severity of the hemolytic process in succeeding pregnancies is a rare phenomenon.

RISK FACTORS

Jaundice◦ onset is usually within the first 24 h of life

Anemia

CLINICAL MANIFESTATIONS

Blood type and Rh factor in the mother and the infant

Increased reticulocyte count Direct Coombs' test (direct antiglobulin

test)◦ Because there is very little antibody on the red

blood cell (RBC), the direct Coomb's test is often only weakly positive at birth and may become negative by 2-3 days of age.

DIAGNOSIS

Blood smear◦ microspherocytes, polychromasia proportionate to

the reticulocyte response, and normoblastosis above

the normal values for gestational age. Indirect hyperbilirubinemia

DIAGNOSIS

Phototherapy Exchange transfusion IVIG

◦ By blocking neonatal reticuloendothelial Fc receptors, and thus decrease hemolysis of the antibody-coated RBCs, high-dose IVIG (1 g/kg over 4h) has been shown to reduce serum bilirubin levels and the need for blood exchange transfusion with ABO or Rh hemolytic diseases.

MANAGEMENT

BABY BLOOD TYPE A(weak expression of Antigen A)

ABO incompatibility: Transfer of Anti-A and Anti-B from the Mother

who is Blood Type O

HEMOLYSIS

Baby now has Anti-A and Anti-B

What type of Blood to transfuse in anemic patients with ABO incompatibility?

Transfuse Adult Blood that is Blood Type A

(contains strong expression of Antigen A)

Since Baby has Anti-A and Anti-B in ABO incompatiblity

RESULT: HEMOLYSIS of the transfused blood

Transfuse Blood Type O (contains Anti-A and Anti-B)(does not contain antigens)

RESULT: No further hemolysis of the transfused blood