RhD prophylaxis concerns RhD negative women, who are non-sensitized against D
antigen during and at the end of their pregnancy with a RhD positive child. RhD prophylaxis includes targeted prophylaxis (prevention of
anti-D immunization after feto-maternal
hemorrhage (FMH) induced by prenatal events and delivery) and routine antenatal D prophylaxis (prevention of
anti-D immunization resulting from spontaneous FMH in the last trimester of pregnancy). Targeted prophylaxis should be applied regardless of the gestational age and a dose of 100microg
anti-D is usually enough (200microg is the lowest dosage currently available in France). However it is recommended to quantify the volume of feto-maternal
hemorrhage to avoid administration of a dose of
IgG anti-D less than 20microg per ml of fetal red blood cells. Efficacy of prophylaxis relies also on the delay between the sensitizing event and the injection of
anti-D, delay should be less than 72 hours.
Intravenous administration of
anti-D allows immediate neutralization of D positive fetal red blood cells and should be, if possible, preferred to intramuscular administration (IM). After a first injection of
anti-D, if repetition of potential sensitizing events occurs, abstention of prophylaxis is possible depending on the previous administrated dose (protection lasts 6 weeks for 200microg and 9 weeks for 300microg) and the amount of feto-maternal
hemorrhage. For routine prophylaxis of the third trimester, 300microg of
anti-D should be proposed IM at 281+/-GW. Abstention of Rh prophylaxis is possible if the alleged father is certified RhD negative or if the fetal RhD genotype is confirmed negative. At delivery, RhD phenotype of the newborn should be determined even if RhD fetal genotype is known. Maternal blood should be drawn for quantification of feto-maternal transfusion at least 30 min after delivery is completed.