NORMAL NUCHAL TRANSLUCENCY VALUES

• Nuchal translucency thickness identifies a group of fetuses that are at an increased risk for trisomies 21, 13 , 18, Turner's Syndrome and some trisomies. It does not appear to be a risk factor for other trisomies, chromosomal deletions, mosaicism and some sex chromosome abnormalities.
• It is also a risk factor for other fetal defects
• Nuchal translucency values modify the background risk:
• No value is good.
• No value is bad.
• The more the value moves away from the mean, the higher the risk.
• The less the value moves away from the mean, the lower the risk.
• A normal value does not mean the fetus does not have a chromosomal or other abnormality.
• Normal values:
• 2.2 mm at a CRL of 38 mm (95th percentile).
• 2.8 mm at a CRL of 84 mm (95th percentile).

Graph of nuchal translucency thickness versus CRL