Clinical Significance

The passage of erythrocytes from an Rh-positive fetus into the circulation of an Rh-negative mother results in the formation of specific Rh antibodies. In subsequent pregnancies, these antibodies are readily transmissible through the placenta into the circulation of the fetus. The action of these antibodies on the Rh-positive cells of the fetus may result in a disease known as erythroblastosis.

Rh-negative mothers who have been sensitized to the Rh factor because of a fetal/maternal hemorrhage are administered specific gamma globulin containing anti RhO (D) to suppress the immune reactions. The amount of gamma globulin administered is calculated by assessing the magnitude of the fetal/maternal hemorrhage. This test is also used to detect fetal – maternal hemorrhage in expectant mothers who have had a trauma to the abdomen.