The search for fetal cells in the maternal circulation

Currently, all methods of prenatal diagnosis require an invasive approach. The next step in the continuing challenge to make prenatal diagnosis more accessible is the development of a noninvasive test. The presence of fetal cells in the maternal circulation has been debated for several decades, but traditional attempts to identify the rare fetal cell within the pool of maternal cells have met with partial success at best. Today, with the aid of highly sensitive and specific techniques such as fluorescent activated cell sorting, polymerase chain reaction, and in-situ hybridization, the task of finding the "on-in-a-million" fetal cell is moving from the realm of the imagination into that of reality.