CYTOGENETIC ANALYSIS OF 2928 CVS SAMPLES AND 1075 AMNIOCENTESES FROM RANDOMIZED STUDIES

We report cytogenetic results from a randomized Danish chorionic villu s sampling (CVS) and amniocentesis (AC) study including 2928 placental and 1075 amniotic fluid specimens processed in the same laboratory. T he results are presented in groups comparing CVS with amniocentesis an d transabdominal (TA) CVS with transcervical (TC) CVS as randomized. M ore abnormalities and more ambiguous diagnostic problems were found in placental tissues than in amniotic cells. There were no diagnostic er rors and no incorrect sex predictions. Mosaicism was detected in 1 per cent of all cases of CVS (discordancies included). When confirmation studies were done, 90 per cent were found to be confined to the placen ta. Eight cases (0.7 per cent) of mosaicism/pseudomosaicism were seen in amniotic fluid specimens, and two cases of five with confirmation s tudies were confirmed in the fetus. The rate of mosaicism/pseudomosaic ism in CVS and AC specimens differed (p<0.05). The rate of pseudomosai cism in cultures of villi and amniotic fluid cells was 0.5 and 0.6 per cent. respectively. Single-cell aneuploidy was observed in 1.8 per ce nt of villi and 1.4 per cent of amniotic fluid cell specimens. Materna l cell contamination (MCC) was seen more often after TC sampling (4.5 percent) compared with TA sampling (1.5 percent), but posed no problem s in interpretation. Compared with the processing of cultured specimen s, the short-term method of preparation of villi in our laboratory dou bled the technicians' workload. For practical and economic reasons we have ceased the routine use of short-term preparations.