ABO and Rh phenotyping of foetal blood obtained by foetoscopy

Abstract

Blood samples taken from the fetus by fetoscopy early in the 2nd trimester of pregnancy can be used for reliable blood grouping and prenatal diagnosis. The sampling technique is not perfect. In 5 out of 15 pregnant women, no fetal blood was obtained, although between 1 and 10 samples were taken on each occasion. Of 56 samples from the 10 women 1/3 contained fetal blood. Contamination of samples with amniotic fluid varied but did not interfere with the blood grouping. ABO and Rh typing of the fetus was possible even if the samples were contaminated with large amounts of maternal blood. In 9 cases, blood grouping of the fetus was performed on red cells from fetoscopy samples. Control blood samples from the fetus following abortion were obtained in 7 of these cases and the fetoscopic results were confirmed.