Detection of fetal nucleated red blood cells in the maternal circulation by Kleihauer test

Maternal blood was obtained from 18 pregnant women at 7 to 25 weeks of gestation. After Percoll discontinuous density gradient centifugation, the fetal nucleated red blood cells (NRBCs) were stained with Kleihauer test. Positive fetal cells appeared with an intense red cytoplasmic staining while maternal cells with adult haemoglobin were colourless. Individual positive NRBC was collected by micromanipulator and whole genome amplification was then performed to determine sex and STR status. This allowed the simultaneous verification of the fetal origin of NRBC and prenatal diagnosis of genetic diseases. The non-invasive prenatal genetic diagnosis of 9 fetuses at high risk of Duchenne muscular dystrophy (DMD) was completed successfully. The Kleihauer test is a rapid, simple and direct chemical staining method to select fetal cells and can be applied in prenatal diagnosis.