[Value of RHD fetal genotyping in the prevention of anti-D immunization]

Anti-D prophylaxis is currently applied in France after birth of an RhD positive infant, after interruption of pregnancy and after some antenatal immunizing events (amniocentesis...). However this program does not cover all the prenatal exposures to fetal RhD antigen, and maternal Rh immunization continues to occur. DNA RhD genotyping of the fetus is now reliably performed on amniotic fluid, and pre diagnostic studies on fetal DNA extracted from maternal plasma are promising. The widespread use of fetal RhD genotyping on maternal blood would allow the antenatal administration of Rh immunoglobuline in all Rh negative patients bearing an Rh positive fetus, insofar as it would preclude exposing the other Rh negative patients to the above plasma derived and rather expensive blood product.