What is the optimal gestational week for performing nuchal translucency (NT) screening?

The optimal time to perform nuchal translucency (NT) screening is around 11–13 weeks of gestation. NT measurement is ineffective if performed too early—i.e., when the fetus is too small—or too late, as the nuchal translucency (fluid-filled space at the back of the fetal neck) naturally disappears with advancing gestational age, rendering the test meaningless. NT screening helps detect potential fetal structural abnormalities. If the NT result indicates an increased risk, further testing—such as maternal serum screening (triple/quad screen) or non-invasive prenatal testing (NIPT)—is recommended.