ABO incompatibility

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Related to ABO incompatibility: Coombs test

ABO Incompatibility

A type of blood incompatibility in which recipients—e.g., those with genotypes AO, BO, OO—of donated blood products, usually understood to mean packed red cells, have antibodies to antigens A or B on the surface of red cells being transfused.

ABO incompatibility

Transfusion medicine A type of blood incompatibility, in which certain recipients–eg genotypes AO, BO, OO of donated blood products-usually understood to mean packed RBCs, has antibodies to antigens–A or B on the surface of RBCs being transfused. See ABO system.

ABO incompatibility

An antigen-antibody immune response to infusion of another's red blood cells. Transfusion reactions occur most commonly in people with type O blood, which carries no antigens on the red blood cells and contains both anti-A and anti-B antibodies. People with type A blood carry A antigens on their red cells and anti-B antibodies; those with type B blood carry B antigens and anti-A antibodies; those with type AB blood carry both A and B antigens but no antibodies to A or B. The antibodies are called natural antibodies because their formation does not require sensitization by A and B antigens. The antibodies recognize the antigens on the donor cells as foreign and destroy them by agglutination and lysis. ABO incompatibilities are different from Rh incompatibilities, which are most commonly related to the D antigen in the Rh blood group. See: table; blood group

Obstetrics: Transplacental fetal-maternal transfusion occurs when fetal blood cells escape into the maternal circulation, eliciting antibody formation. Maternal antibodies then cross the placenta into the fetal circulation, attack, and destroy red blood cells, as evidenced by neonatal hyperbilirubinemia and jaundice.

See also: incompatibility