Rapid prenatal karyotyping using foetal blood obtained by cordocentesis.

Bdckground.Prenatalkaryotypingusing foetalbloodsamples obtained by cordocentesis is a useful method of detecting abnormal chromosomes in the foetus. Methods. Cordocentesis was performed in 187 cases for prenatal karyotyping between January 1995 and September 2000. Pregnant women were between 18 and 38 weeks of gestation and their ages ranged from 18 to 40 years. The common indications were ultrasonographic abnormalities (47.6%), history of previous Down syndrome (13.3%), advanced maternal age (11.7%), low maternal serum alpha foetoprotein levels(10.7%), previouschild with malformation (10.7%), previous child with trisomy (chromosome 13/1 8) (2.6%), parent a balancedtranslocationcarrier (1.6%) and high maternal serum alpha foetoprotein levels(1.6%). Results. Analysis of 137 successful cultures showed 8 (5.2%) karyotype abnormalities.The remainingsamplescould not be reported due to the presence of maternal contamination of the sample (12.3%), inadequate sample (6.4%) or culture failure(9.8%). In those with an abnormal karyotype, obstetric management could be altered appropriately. Conclusion.In foetuses at high risk of a chromosomal aberration, a rapidly obtained karyotype is helpful in obstetric management.