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Nuchal Translucency or Early Anatomy Ultrasound

This is a test that can screen for pregnancies with an increased chance of certain genetic conditions.
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Overview

The nuchal translucency (NT) or early anatomy ultrasound is a diagnostic test done in the first trimester to check on the development of your pregnancy.

Ultrasounds use sound waves to safely produce an image of the developing fetus.

The NT ultrasound is also used as part of the screening tests that identify pregnancies with an increased chance of some genetic conditions. This ultrasound measures the amount of fluid present at the back of the fetal neck. A high amount of fluid can indicate an abnormality.  

First trimester screening (FTS) combines those measurements with blood test results to identify pregnancies at a higher chance of the following conditions:

  • Down syndrome
  • Trisomy 13
  • Trisomy 18
  • Open neural tube defects which affect the brain or spine (IPS only) 

More about NT or early anatomy ultrasound

What to expect

The NT or early anatomy ultrasound is done between 11 and 14 weeks of pregnancy. While the ultrasound procedure itself takes about 20 minutes, your appointment (including a blood test), can take more than three hours. Complications that are discovered during any ultrasound scheduled on the same day as yours may increase the waiting times for all appointments.

Your health-care provider will receive the ultrasound report within a few days. If the ultrasound shows any cause for concern, your health-care provider will contact you. They might also suggest meeting with a genetic counsellor to further discuss your results.  

The NT and early anatomy ultrasound can tell you:

  • If your pregnancy carries a higher risk of certain genetic conditions
  • The (gestational) age of your pregnancy and your estimated due date
  • If your pregnancy is progressing normally so far
  • If you are pregnant with twins or more (multiples)  
  • Information about the placenta, which provides oxygen and nutrition to the fetus 
Risks and limitations

There are no risks from NT or early anatomy ultrasounds for you or your pregnancy.  

The main limitations of NT or early anatomy ultrasounds include the accuracy the test and the types of conditions the test can screen for.

The NT ultrasound cannot provide a definitive diagnosis of genetic conditions. It is part of a screening test that can tell you how likely it is that your pregnancy might be affected by certain genetic conditions. Additional tests are needed to receive a diagnosis.  

Not all birth defects can be seen in an early anatomy ultrasound. A second ultrasound is typically recommended between 18 and 20 weeks to check how the fetus is developing.