Fetal nuchal translucency: ultrasound screening for fetal trisomy in the first trimester of pregnancy

The risk of fetal trisomy can be derived by combining maternal age and fetal nuchal translucency thickness at 10 to 13 weeks of gestation. It is predicted that for a false positive rate of 5%, the sensitivity of the new method of screening would be at least 85%, which compares favourably with the respective 20 to 30% and 50 to 60% of screening based on maternal age alone or the combination of maternal age with maternal serum biochemistry.