EARLY FILTRATION AMNIOCENTESIS FOR FURTHER INVESTIGATION OF MOSAICISMDIAGNOSED BY CHORIONIC VILLUS SAMPLING

In 44 pregnancies where chorionic villus sampling (CVS) had shown mosa icism, early amniocentesis using a filter technique was carried out wi th the purpose of clarifying the fetal karyotype and reducing the wait ing time for a final karyotype. Since the filter technique increases t he cell yield of the amniotic fluid sample, it was hypothesized that t his technique could be applied as soon as the mosaic CVS result was av ailable, without compromising the culturing of the amniotic fluid cell s. The mean gestational age at amniocentesis was 12.5 weeks and the me an gestational age at the time of the final karyotype was 13.9 weeks. All amniotic fluid sampling procedures and cultures were successful. F our pregnancies were terminated due to abnormal karyotypes (9.1 per ce nt). Two spontaneous abortions occurred in the second trimester (5.0 p er cent), and one infant was lost at term due to unexplained intrapart um death. The total fetal loss rate was 7.5 per cent. This loss rate i s concordant with other reported series where the outcome of pregnanci es with placental mosaicism has been evaluated. We:conclude that early amniocentesis with the filtration technique is a useful method for fo llow-up on CVS, mosaicism, providing results prior to 14 weeks of gest ation.