Fetal nuchal translucency and skinfold to screen for fetal aneuploidy

Abstract

Nuchal translucency (NT) is defined as the accumulation of subcutaneous fluid in the nuchal region of the fetus at 11–14 weeks. Its measurement in order to modify the previous background risk has been proved to be able to detect around 70% of trisomy 21 pregnancies (for a 5% fixed positive rate). When affected fetuses dying before 20 weeks are excluded, detection rate may decrease to 60%. Given that appropriate training of sonographers and adherence to a standard technique for the measurement of NT is of paramount importance to reduce variability, the Fetal Medicine Foundation has established a certification process. Fetal nuchal edema displayed at 15–20 weeks was described as enlarged nuchal skinfold, and is a less sensitive but more specific marker than nuchal translucency. Webbing of the neck in infants with trisomy 21 may be envisaged as the remainder of nuchal distension.