Comparison of maternal and fetal chromosome heteromorphisms to monitor maternal cell contamination in chorionic villus samples.

Maternal cell contamination (MCC) presents a potential problem in the analysis of chorionic villus sampling (CVS) preparations for early prenatal diagnosis by chromosomal, biochemical and molecular methods. Through the comparison of fluorescent chromosome variants from CVS and maternal cells, we found three out of 50 samples to have MCC. One of these was observed on a direct preparation. Routine chromosome heteromorphism analysis is suggested as a reliable method for monitoring MCC in CVS specimens.