Simultaneous placentacentesis and amniocentesis for prenatal karyotyping: report on 250 cases

The efficacy and risks of simultaneous transabdominal chorionic villus biopsy (placentacentesis) and amniocentesis in the second and third trimesters were evaluated in 250 singleton pregnancies. The major indications were advanced maternal age (36.0 per cent), abnormal ultrasound findings (23.2 per cent), and low maternal AFP value (17.6 per cent). Nine abnormal karyotypes were found in placental tissue (3.6 per cent). The karyotypes of placental and amniotic cells were different in three cases, including two cases of false-positive mosaicism (0.8 per cent) and one case of a false-negative result (0.4 per cent) obtained by placental karyotyping. The problem of discrepant karyotypes in embryonic and extra-embryonic tissue does not seem to be restricted to the first trimester. The post-procedure fetal loss rate was estimated as approximately 1.8 per cent. We conclude that the procedure presented here combines the advantages of rapid karyotyping (placentacentesis) and high diagnostic reliability (amniocentesis). It does not seem to be necessary to restrict its use to late presentations and suspicious ultrasound findings.