The use of nuchal translucency in contemporary obstetric practice

Nuchal translucency sonography is the most powerful single prenatal marker for Down syndrome. Its detection rate is 75% at a 5% false-positive rate. The combination of nuchal translucency and maternal serum-free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A can identify 85% to 90% of fetuses with Down syndrome for a false-positive rate of 5%. This method can also identify more than 90% of fetuses with trisomies 18 and 13, Turner syndrome, and triploidy for a screen-positive rate of 1%.