Cordocentesis for rapid karyotype: 421 consecutive cases.

Between October 1985 and December 1993, 421 patients underwent fetal blood sampling for rapid karyotyping (426 samplings, 5 twin pregnancies). The aim of the study was to evaluate cordocentesis in terms of results, complications and additional information in this specific indication especially in case of abnormal pregnancy sonogram. The fetal loss rate possibly related to fetal blood sampling was 1.9%. Abnormal sonograms represented 91% of rapid karyotype indications. Chromosomal abnormalities were found in 9.5% of abnormal sonograms and in 16.9% of fetal structural anomalies (37 cases). The commonest chromosomal abnormality was trisomy 21 (11 cases). In conclusion, cordocentesis is a safe and reliable method for rapid karyotyping although it is associated with more risks than in other indications (congenital infections). The high rate of chromosomal abnormalities pleaded for ultrasonographic screening in a population usually not investigated by cytogenetic studies.