Clinical Significance

There is a system to identify all potential Rh immune globulin candidates. Potential Rh immune globulin candidates include: pregnancy termination through delivery or abortion, amniocentesis, invasive obsetric procedures, and abdominal trauma during pregnancy.

High-titered IgG D antibodies of human origin (RhIG) are commercially available for use in preventing alloimmunization of the D antigen. The risk of a D-negative mother becoming immunized by a D-positive fetus can be reduced from about 16% to less than 0.1% by the appropriate administration of RhIG.

One vial of RhIG will suppress the immunity of 30 mL of whole blood or 15 mL red blood cells. RhIG is recommended at 28 weeks for all D negative women. D negative women who undergo miscarriage, abortion, ectopic pregnancy, or amniocentesis should be considered candidates and receive RhIG within 72 hours of such events. Since the Rh type of the fetus is not known, it must be assumed to be D positive. It should be administered within 72 hours after delivery of a D positive infant.