Fetal blood grouping using cell free DNA - an improved service for RhD negative pregnant women

Red cell alloimmunisation involves the transplacental movement of maternally derived red cell antibodies into the fetal circulation, causing red cell haemolysis, fetal anaemia and ultimately fetal death. Current standard UK practice is to prevent sensitisation to the D antigen by administering anti-D at about 28 weeks' gestation to all RhD negative pregnancies. The determination of fetal blood group by non-invasive cell free fetal DNA testing offers an improved and more efficient service to RhD negative pregnant women and avoids the potential iatrogenic harm associated with standard practice. It also has significantly improved the management of women with red cell alloimunisation to D and other antigens. This review summarises the past and future management of red cell alloimmunisation during pregnancy and the impact of ffDNA tests.