Prevention of Rhesus Alloimmunization

Anti-Rho(D) antibody causes severe hemolytic disease of the newborn

Occurs when a Rho(D)-negative woman carries a Rho(D)-positive fetus and develops antibodies against Rho(D)

The antibody developed against Rho(D) persists and poses a threat of hemolytic disease in subsequent Rho(D)-positive fetuses

Passive immunization of Rho(D)-negative mothers after delivery destroys fetal Rho(D)-positive cells and prevents formation of antibodies, which would cause disease in subsequent Rho(D)-positive gestations

Routine antibody screen is positive

Because hemolytic disease may occur in association with Rh subgroups or other red blood cell antigens, atypical antibodies should be assessed at 28 weeks in all pregnancies

Rho(D) immunoglobulin (Ig) is given to a Rh_o(D) negative mother within 72 h after delivery to prevent future erythroblastosis

Additional protection is afforded by the routine administration of the Ig at week 28 to all Rh_o(D) negative mothers; the passive antibody titer is too low to harm the Rho(D)-positive fetus

Rho(D) Ig should also be given after abortion, ectopic pregnancy, placental abruption, other antepartum bleeding

Once a woman is alloimmunized, Rh_o(D) immune globulin is no longer helpful and should not be given