How Accurate is the Nuchal Translucency Scan?

One of the main purposes of the Nuchal Translucency Scan is to assess the risk of chromosomal abnormalities such as Down’s syndrome. The size of the nuchal fold at the back of the neck can be a good indication of this risk when it is measured during ultrasounds taken between 11 and 14 weeks. However, the scan cannot diagnose a chromosomal abnormality. It can only tell us if there is a higher than normal chance of one.

Nuchal Translucency Scan

Understanding Your Nuchal Translucency Scan Results

When you have a Nuchal Translucency Scan, the doctor or sonographer will measure the width of the nuchal fold, a fluid-filled area at the back of the baby’s neck. The size of the nuchal fold usually falls within a certain range that depends on the size and age of the baby. If the measurement is outside this range then it indicates a higher than usual chance of certain chromosomal abnormalities. However, the test isn’t perfect:

  • The Nuchal Translucency Scan can’t identify every baby with a chromosomal abnormality. For example, if 100 babies with Down’s syndrome are scanned, only 85 of them would show up as having an unusual nuchal fold. The rest would be missed.
  • Some babies may be classed as high probability even though they don’t have any abnormalities. If 100 babies without any chromosomal abnormalities are scanned, 5 of them would produce a high probability result.

It is therefore important to understand that the Nuchal Translucency Scan results can only tell you if your baby has a high or normal probability of chromosomal abnormalities.

What Next?

Although the Nuchal Translucency Scan can’t be used to diagnose a chromosomal abnormality, it is a very useful screening test during pregnancy. The results can help to guide your decisions about further tests. For example, if the scan suggests that there is a higher probability of an abnormality, you may want to have non-invasive prenatal testing (NIPT) to learn more. You will be able to discuss the results of the Nuchal Translucency Scan and other screening tests with your doctor to ensure that you understand what they mean for you and your baby.

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137 Harley Street, London W1G 6BF
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Regent’s Park
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Talbot Road, Talbot Road, Alderley Edge, Cheshire SK9 7HR
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