Associations Thickening of the nuchal translucency can be associated with a number of anomalies, including: aneuploidy trisomies (including Down syndrome) Turner syndrome non-aneuploidy structural defects and syndromes congenital heart disease: risk varies from 2% at the 95th percentile to 5% at the 99th percentile (3.5 mm), with septal defects the commonest abnormality 10 Noonan syndrome: the only genetic molecular condition with a clear association with increased nuchal translucency congenital diaphragmatic herniation omphalocele skeletal dysplasias Smith-Lemli-Opitz syndrome VACTERL association miscarriage or fetal demise: the risk is directly proportionate to increased nuchal translucency thickness and ranges from 1.6% with NT between 95 - 99th percentile to 20% with NT >6.5 mm 11 intrauterine infections: Parvovirus B19 is the only specific pathogen with direct relation to increased NT due to the effect of fetal anemia and fetal myocardial infarction Radiographic features Nuchal lucency is measured on a sagittal image through the fetal neck.