Nuchal Translucency Testing

Nuchal Translucency testing is a first trimester genetic screening test that is about 90% accurate in detecting Down's Syndrome, Trisomy 18 and other chromosomal abnormalities. It consists of an ultrasound and a blood test. Together the results allow each patient to have a relatively accurate indication of their baby's risk for a chromosomal abnormality. The ultrasound test is comprised of measuring the fetal nuchal fold thickness, maternal age and gestational age. The blood test from the mother measures two proteins in the blood (free Beta Human Chorionic Gonadotropin and PAPP-A; Pregnancy Associated Plasma Protein A). This test can only be performed between 10 weeks 4 days and 13 weeks 5 days gestation. This test has a 5% false positive rate.

All other genetic screening tests are done in the second trimester. The Alpha Fetal Protein test is a blood test performed on the mother and is only 80% accurate. Amniocentesis and Chorionic Villi Sampling (CVS) are more invasive and have a risk of miscarriage associated with them but they are the most accurate.