 Other common chromosomal defects that cause a thicker nuchal translucency are

In fetuses with a normal number of chromosomes, a thicker nuchal translucency is associated with other fetal defects and genetic syndromes.Nuchal scan (NT procedure) is performed between 11 and 14 weeks of gestation, because the accuracy is best in this period.The scan is obtained with the fetus in sagittal section and a neutral position of the fetal head (neither hyperflexed nor extended, either of which can influence the nuchal translucency thickness).