Chorionic villus sampling in continuing pregnancies. II. Cytogenetic reliability.

Cytogenetic analysis was performed on 103 chorionic villus samples. Analysis of the 103 samples revealed six abnormalities. In three of the six the abnormalities were confirmed in fetal or neonatal tissue (47,XY, + 13; 46,XY, t(13q13q); 45,X). In three samples the abnormalities detected were not confirmed; in two of the three the abnormalities were detected only in long-term cultures, whereas in the other samples the abnormality was restricted to direct analysis of the villi after overnight incubation. Our initial experience leads us to conclude that certain abnormalities in chorionic villus sampling may not be indicative of fetal abnormalities; 45,X/46,XX or 45,X/46,XY mosaicism is such a complement. Discrepancies between cytogenetic analysis of intact villi processed soon after sampling and of cells grown in culture can be managed by adhering to several suggested guidelines and by liberal use of confirmatory amniocentesis.