Nuchal Translucency

What Is Nuchal Translucency?

How is nuchal translucency screening done?

Your healthcare provider performs an abdominal ultrasound. (Sometimes, they’ll perform a vaginal ultrasound instead.) They spread gel on your stomach and move a handheld wand across it. The wand sends images of the fetus to a screen. This is where your provider measures the fluid-filled space behind its neck. The fluid area is measured in millimeters.

How are the results calculated?

The results of your NT scan aren’t usually calculated alone. Your healthcare provider will typically combine findings from all your first-trimester screenings to calculate your child’s risk of a congenital condition. Looking at several tests improves the accuracy of the screening.

A normal amount of fluid means the chances of a congenital condition are lower. An increased amount of fluid means there’s a higher chance that a condition is present. For example, your result may show a 1 in 300 chance. This means that for every 300 fetuses with that fluid measurement, only one of them had a congenital condition.

It’s important to note that your provider won’t diagnose anything based on the results of an NT scan. NT scans are screenings. They only tell you the likelihood of your child having a condition. Your provider uses your results to determine whether further testing is necessary.

How accurate is the test?

NT screenings alone can detect about 70% of Down syndrome cases. Many healthcare providers combine results of an NT ultrasound with blood screenings. The accuracy of predicting conditions increases to about 95% when combined with noninvasive prenatal testing (NIPT).

Are there any risks to the screening?

No, nuchal translucency is a low-risk screening. It only uses ultrasound.

Can NT show if it’s a boy or girl?

No. This screening isn’t used for finding out your baby’s sex.

How long does it take to get results?

Most healthcare providers can read the NT ultrasound on the same day. Blood work collected from the first-trimester screening will take at least a few days or weeks to return. Most providers will wait until they have all the results to calculate whether the fetus is at risk.

What is a normal nuchal translucency measurement at 12 weeks?

If the NT measurement is higher than 3 mm at 12 weeks, your provider will usually talk with you about doing more testing.

What happens if the results are abnormal?

NT screenings only show the risk of the fetus having a condition. If your screening is abnormal, your healthcare provider can use other tests to diagnose the condition. These include chorionic villus sampling (CVS) or amniocentesis. Your provider may also want to take a closer look at your child’s heart with a fetal echocardiogram.

Try not to panic. Just because your results are irregular doesn’t mean there’s a problem. Your provider will run further tests. Or they’ll look for other signs of a problem on your ultrasound or in your bloodwork. They may refer you to a genetic counselor. A genetic counselor can help you better understand the conditions your child may have.

Does an abnormal scan mean my baby has Down syndrome?

No, an abnormal nuchal translucency scan doesn’t diagnose anything. It can mean your child is at a higher risk of having Down syndrome. Healthcare providers prefer to use a blood test in addition to the NT scan. That’s because it’s a more accurate assessment of the risk.

Do I need both NIPT and NT?

No. But you should talk to your healthcare provider before making any decisions on which screenings to have. They can help you understand the pros and cons of each. They can also help you figure out which one might be best for you. Things like health history, insurance and risk factors can play a role in your decision. The main difference is that NIPT is a blood test, while NT is an ultrasound.