Submicroscopic chromosomal abnormalities in fetuses with increased nuchal translucency and normal karyotype

To investigate the submicroscopic chromosomal abnormalities in fetuses with increased nuchal translucency (NT) and normal karyotype.

Total of 296 fetuses with increased NT (≥3.0 mm) were tested by conventional karyotyping. When cytogenetic analysis showed normal chromosome, the pregnancies were then consulted for array-comparative genomic hybridization (CGH) analysis and received subsequent morphology scan between 20 and 24 weeks gestation. Submicroscopic chromosomal abnormalities were assessed and compared between the fetuses with and without structural defects.

Chromosomal abnormality was identified in 19.9% (59/296) fetuses. Two hundred and twenty samples were tested by array CGH. Submicroscopic chromosomal abnormalities were detected in 9.1% (20/220) fetuses. For the fetuses with abnormal morphology scan, the detection rate of submicroscopic chromosomal abnormalities was higher than those with normal morphology scan (26.9% versus 6.7%, p < 0.05).

Submicroscopic chromosomal abnormalities should be accessed when the fetus was found to be with increased NT and normal karyotype, especially when the structural defects were found at second or third trimester.