Evaluation of the results of screening for fetal sex chromosome aneuploidy by non-invasive prenatal testing

Abstract

Objectives: To investigate the results of screening for fetal sex chromosome aneuploidy (SCA) by non-invasive prenatal testing (NIPT). Methods: A cross-sectional study was conducted on 1,200 pregnant women who underwent NIPT for SCAs at the Centre of Clinical Genetics and Genomics, Hanoi Medical University Hospital, from 2021 to 2022. Pregnant women with high-risk NIPT results were confirmed by karyotyping from cultured amniotic fluid cells. Results: The average maternal age was 31±4 years. The proportion of women who underwent other antenatal screenings before NIPT was 63.0%, of whom 58.1% were classified as low risk and 4.9% as high risk. The rate of NIPT-positive results for SCAs was 0.67%. The positive predictive value (PPV) of all positive NIPT results for SCAs was 62.5% (5/8). The lowest individual PPV was observed for monosomy X at 25% (1/4). Conclusions: NIPT can be useful for screening fetal SCAs, but it is not a diagnostic test. Among the SCAs, monosomy X had the highest false-positive rate. All pregnant women with positive NIPT results for SCAs should receive genetic counselling and undergo confirmatory prenatal diagnostic testing.