Accuracy of prenatal determination of RhD type status by polymerase chain reaction with amniotic cells

The RhD blood type of fetuses may be determined early in pregnancy through the analysis of amniotic fluid without sensitizing the mothers' blood to the fetus's different blood type. Such analysis may enable doctors to know whether or not to treat the mother with anti-D immunoglobulin to prevent sensitization of the mother's blood and poor outcomes for the fetus. Researchers performed amniocentesis on 95 pregnant women whose blood was RhD negative and where the father's blood was RhD positive. Amniotic fluid was analyzed for fetal RhD type by polymerase chain reaction and the results were compared to either fetal blood samples or to samples of umbilical cord blood after birth. Thirty-six fetuses were correctly typed as RhD negative, and 96 of 98 fetuses were correctly typed as RhD positive.