USG feature used to diagnose fetal aneuploidy in regular antenatal ultrasonography is?

Nuchal translucency: This is the maximum thickness of the subcutaneous translucent area between the skin and soft tissue overlying the fetal spine at the back of the neck It is measured in the sagittal plane between 11 and 14 weeks,when the crown-rump length measures between 38 and 84 mm. When the nuchal translucency is increased, the risk for fetal aneuploidy and various structural anomalies--including hea defects--is significantly elevated. If seen in the first-trimester, fetuses with cystic hygromas are five times more likely to be aneuploidy than the fetuses with an increased nuchal translucency.