First trimester prenatal diagnosis using transcervical cells: an evaluation.

Human trophoblastic cells can be retrieved by minimally invasive procedures from the endocervical canal between between 6 and 15 weeks gestation. The incidence with which fetal cells can be detected in transcervical cell (TCC) samples varies according to the method of collection and the molecular techniques employed for their identification. Fluorescence in-situ hybridization (FISH) and polymerase chain reaction (PCR) assays have been successfully used to detect aneuploidies and Y-derived DNA sequences in TCC samples obtained from male fetuses. Chromosome specific polymorphic DNA sequences (small tandem repeats) have also been employed to identify, by quantitative fluorescent PCR, fetal cells in TCC samples. Furthermore, Rh(D) sequences have been amplified in samples retrieved from Rh(D) negative mothers. Preliminary results also suggest that prenatal diagnoses of thalassaemia and sickle cell anaemia can be performed on clumps of cells isolated from TCC samples. Overall systematic studies allow optimism about the possibility of using TCC samples for the prenatal diagnosis of selected inherited disorders.