The nuchal translucency ultrasound is performed between weeks 11 and 14 of gestation. The presence of subcutaneous fluid behind the fetal neck (nuchal translucency) is observed during the ultrasound, while the pregnancy age and possible delivery date are determined. The ultrasound check is completed with a lab test for two maternal hormones (PAPP-A, β-hcg), aiming to determine the risk of development of three very common chromosomal anomalies (Down syndrome / trisomy 21, Patau syndrome / trisomy 13, Edward’s syndrome / trisomy 18).