Screening for chromosomal abnormalities in an unselected population by fetal nuchal translucency.

The aim of this prospective study was to examine the value of nuchal translucency measurement for the detection of fetal aneuploidies in an unselected population of an Austrian National Health Service hospital. A total of 1972 women with singleton pregnancies who attended at 10-13 weeks for the initiation of routine antenatal care at our hospital were examined. Chromosomal abnormalities were found in 11 fetuses, four of then with Down's syndrome. Eight of the 11 chromosomally abnormal fetuses, including two of the four with Down's syndrome, were detected by a nuchal translucency thickness of > or = 2.5 mm. Three of the fetuses with abnormal karyotype had a nuchal translucency thickness of < 2.5 mm. Two of these were fetuses with Down's syndrome, one of which was identified by karyotyping for maternal age, the second one by positive biochemistry testing (triple test). The additional chromosomal abnormality was identified by karyotyping for maternal age. These data suggest that nuchal translucency screening for aneuploidies is efficient even in an unselected population.