Rh Incompatibility Medication

Updated: Mar 15, 2017
  • Author: Leon Salem, MD, MS; Chief Editor: Bruce M Lo, MD, MBA, CPE, RDMS, FACEP, FAAEM, FACHE  more...
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Medication

Medication Summary

Rh IgG, first released for general use in 1968, has been remarkably successful in the prevention of Rh incompatibility. In the Rh-negative mother, the preparation is administered after a suspected fetomaternal hemorrhage. The exact mechanism by which passive administration of Rh IgG prevents Rh immunization is unknown. The most likely hypothesis is that the Rh immune globulin coats the surface of fetal RBCs containing Rh antigens. These exogenous antibody-antigen complexes cross the placenta before they can stimulate the maternal endogenous immune system B cells to produce IgG antibodies.

Since Rh IgG became the standard of care in the United States, the risk of Rh incompatibility has been reduced from 10-20% to less than 1%. Because of its short half-life, Rh IgG routinely is administered once at 28-32 weeks' gestation and again within 72 hours after birth to all Rh-negative pregnant females as a part of routine prenatal and postnatal care.

The current recommendation is that every Rh-negative nonimmunized woman who presents to the ED with antepartum bleeding or potential fetomaternal hemorrhage should receive 300 mcg of Rh IgG IM. For every 30 mL of fetal whole blood exposed to maternal circulation, 300 mcg of Rh IgG should be administered. A lower 50-mcg dose preparation of Rh IgG is available and recommended for Rh-negative females who have termination of pregnancy in the first trimester when fetomaternal hemorrhage is believed to be minimal.

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Blood derived product

Class Summary

This agent is effective in preventing Rh isoimmunization.

Human anti-D immune globulin (RhoGAM, BayRho-D, Rhophylac, HyperRho)

Suppresses immune response of nonsensitized Rh O (D) negative mothers exposed to Rh O (D) positive blood from the fetus as a result of a fetomaternal hemorrhage, abdominal trauma, amniocentesis, abortion, full-term delivery, or transfusion accident. Should be administered if the patient is Rh negative, unless the father also is Rh negative.

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