Nucleated red blood cells in maternal circulation and prenatal diagnosis

Almost for four decades it has been possible to perform prenatal diagnosis of aneuploidy and single gene disorders. Routinely used methods like amniocentesis and chorionic villus sampling are invasive procedures and associated with low but definite risk to the foetus and/or mother. The search for safe and reliable noninvasive procedures, thus continued. One such approach is the use of foetal cells in maternal blood. Foetal nucleated RBC (foetal NRBC) has been the focus of research. Foetal gender and foetal RhD blood group (if mother is RhD negative), and genetic alterations (if mother does not have that alteration), are diagnosed with this method. But the results of these noninvasive techniques lack consistency. It may be attributed to a presence of very small number of foetal NRBCs and relatively more number of maternal NRBCs in maternal circulation as well as limited development of cell enrichment procedures. An increase in the NRBCs during pregnancies with aneuploidies and foetomaternal disturbances has been demonstrated and could be used as a screening test in these conditions. The discovery of circulating foetal nucleic acid in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis.