2021/07/25

What Is The Purpose Of A Nuchal Translucency Scan?

During the first trimester of your pregnancy, your primary care physician or OB/GYN might recommend one or several screening tests to determine your baby’s risk of chromosomal abnormalities or a congenital heart defect.

There are many different types of prenatal testing to help determine a baby’s risk of chromosomal abnormalities. These include NIPT, quad screening, and amniocentesis. Though these tests can’t always confirm a diagnosis, they can alert you to potential risks and help you plan for the future. Another common type of screen is a nuchal translucency scan.

What Is A Nuchal Translucency Scan?

A nuchal translucency (NT) scan is a special type of ultrasound conducted toward the end of your first trimester. It helps your primary care physician or OB/GYN determine your growing baby’s risk of a chromosome abnormality.

During an NT scan, your doctor assesses a clear space at the back of your baby’s neck called the nuchal fold. Research shows that babies with chromosome abnormalities tend to collect extra fluid in this area. 

Increased fluid collection doesn’t necessarily guarantee chromosome problems, but it does mean your baby is at an increased risk of:

  • Down syndrome
  • Edwards syndrome
  • Patau syndrome
  • Congenital heart defects

A nuchal translucency scan isn’t 100% accurate and it cannot confirm a diagnosis. Even so, the insights it provides can be extremely valuable.

What Is A Normal Nuchal Translucency Scan Measurement?

Nuchal translucency scan measurements vary depending on how far along you are in your pregnancy. At 12 weeks (the end of the first trimester) most OB/GYN’s consider an NT reading normal if it’s three millimeters or less. Any reading higher than that increases a baby’s risk of a chromosome abnormality or congenital defect. 

Who Should Get A Nuchal Translucency Scan?

Any woman who is pregnant can benefit from a nuchal translucency scan. It’s one of several screening tests that most PCPs and OB/GYNs recommend during the first trimester. 

If your scan determines that your baby is at risk, your PCP or OB/GYN can refer you to a genetic counselor who can explain the results in greater detail. 

What Does A Nuchal Translucency Scan Involve?

A nuchal translucency scan is a brief, in-office procedure that typically takes less than 30 minutes. During an NT scan, your primary care physician or OB/GYN runs a handheld device, called a transducer, over your stomach. The transducer emits high-frequency sound waves that bounce off of your growing baby, creating detailed images. Your provider uses these images to find and measure your baby’s nuchal fold in real-time.

To determine your risk of having a baby with a chromosome abnormality, your provider considers your age, health history, and the size of your baby’s nuchal fold. 

How Accurate Is A Nuchal Translucency Scan?

Nuchal translucency scans are correct about 70% of the time. That means there’s a 30% chance the screen will miss a chromosome abnormality. When combined with other types of prenatal screening, the accuracy of an NT increases to about 92%. 

What If My Nuchal Translucency Scan Is Abnormal?

If you have any questions or concerns, a genetic counselor can answer them and assist you in planning for your baby’s arrival.



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