ABO and Rh phenotyping of foetal blood obtained by foetoscopy

Blood samples taken from the foetus by foetoscopy early in the 2nd trimester of pregnancy can be used for reliable blood grouping. However, the sampling technique is not perfect. In 5 out of 15 pregnant women, no foetal blood was obtained, although between 1 and 10 samples were taken on each occasion. One-third of 56 samples from the 10 women contained foetal blood. Contamination of samples with amniotic fluid varied, but did not interfere with the blood grouping. ABO and Rh typing of the foetus was possible even if the samples were contaminated with large amounts of maternal blood. In nine cases, blood grouping of the foetus was performed on red cells from foetoscopy samples. Control blood samples from the foetus following abortion were obtained in seven of these cases, and the foetoscopic results were confirmed.