[Chromosomal mosaicism after diagnostic chorionic villi biopsy. Subsequent study of the placenta].

Among 311 diagnostic chromosomal analyses after CVS eleven results (mostly chromosomal mosaicism) did not fit completely with the chromosomal sets found in the fetuses and newborns. In all cases chromosomal mosaicism was restricted to the placenta only. All children born after the diagnosis of a chromosomal mosaicism in the placenta were normal. In six cases the investigation of the placenta after termination of pregnancy or birth was possible. In all those cases the mosaicism could be found within the placenta, however, in some cases in a very low percentage. Although occurrence of chromosomal mosaicism in the placenta can hinder chromosomal diagnosis after CVS, the advantages of the method are not neutralized.