Fetal blood group determination in first-trimester pregnancy for the management of severe immunization.

The presence or absence of Rho (D) and Kell antigens on fetal red blood cells was determined in the first trimester of pregnancy on erythrocytes obtained by chorionic villi sampling with the use of mixed agglutination and solid phase microimmunofluorescence techniques. Pregnancies in one Kell-sensitized woman and seven severely RH-sensitized women with a poor obstetric history and a partner heterozygous for the offending antigen were examined. A conclusive diagnosis could be made in seven of the eight cases studied.