Nuchal Translucency Testing

This test is available for the early detection of chromosomal abnormalities and can be done at 11-12 weeks of gestation.

We are certified by The Fetal Medicine Foundation to provide this procedure (we earned this certification and have been performing this test since 2005!)

The Nuchal Translucency Screening Test consists of an ultrasound and a blood test

The ultrasound examines an area on the back of the neck of the fetus, called the nuchal translucency (NT). If the NT is enlarged (too wide), this can be a sign of possible Down syndrome or other anomaly.

The Nuchal Translucency Screening Test results allow us to recalculate the patient’s risk for Down syndrome. The new risk is often lower than the risk calculated using the mother’s age. The new risk becomes the basis for later decision-making.

NOTE: If the NIPT test has been done, it is a better test for Trisomy 21 and 18 than the NT test. Thus, the NT protocol might be modified to an ultrasound only. The following discussion presumes that NIPT was not done.

Decision Making

For example: A 35 year-old pregnant woman has a 1/276 risk of Down syndrome based on her age. This is also the age where genetic testing (e.g. amniocentesis) would normally be offered. If the Nuchal Translucency Screening Test is done, the new risk might be much lower than 1/276 (say 1/1,000), so that a decision can be made NOT to have the amniocentesis. Alternatively, if the new risk is higher, say 1/100, then it might be an easier decision to have the amnio done.

Using the Nuchal Translucency Screening Test we can detect about 80 to 90% of all cases of Down syndrome. Unfortunately, this means that some patients will have normal results and ultimately might still deliver a baby with Down syndrome (which is why NIPT testing is on the way to becoming a routine test for all pregnant women). On the other hand, we can advise many women not to have an amniocentesis, saving them from the possible risk of miscarrying a normal pregnancy (about 2-4 per 1000 amnios).

Does not test for Spina Bifida

Note that the Nuchal Translucency Screening Test does not screen for spina bifida (neural tube defects). Also, if the results are abnormal, it is too early for amniocentesis, so a CVS test may be warranted, which carries with it a slightly higher risk of miscarriage.

NT Measurement Picture