Nuchal (NT) Scan: Diagnostic Ultrasounds in London

The nuchal translucency (NT) scan is a sonographic (imaging) phenomena, which measures the amount of fluid in the filled area under the skin and at the back of the baby’s neck. NT is a non-specific (surrogate) marker of fetal well-being that may be increased in the case of trisomy 21 (Down’s syndrome), Edward’s syndrome, Patau’s syndrome, fetal heart defects, or other structural anomalies.

During the screening test, if the baby is found to have only an increased NT without any other genetic or chromosomal anomalies, it is believed that the nuchal fluid will resolve on its own and the child will be completely healthy. A small proportion of babies with an isolated increase in NT have genetic syndromes or anomalies, which are undetectable before birth.

The NHS consider any NT thickness measurement below 3.5 mm to be normal. However, normal measurements do not rule out all anomalies for your baby but do indicate a lower chance of having a chromosomal problem. More than 50% of babies with severe heart defects, 25% of babies with Down’s syndrome, and the majority of babies with other anomalies will have had a completely normal nuchal dating scan.

In order to gain a better understanding of your baby’s well-being, we use advanced technology to perform an early fetal scan, which is a thorough top-to-toe examination of the fetal anatomy. This allows us to exclude many fetal anomalies by having a closer look at the heart, spine, and brain, among other organs. Additionally, we use a nuchal translucency scan to assess the chance of trisomy 21 (Down’s syndrome). The combination of these approaches is a much more effective way to exclude anomalies than NT measurements alone.

NT is an important non-specific marker of your baby’s well-being, where babies with an increased NT measurement require further evaluation.

We routinely measure NT thickness during the early fetal scan; however, we do not use this to calculate your baby’s chances of having Trisomy 21 (Down’s syndrome). Instead, we use NIPT, which has a much higher detection rate and a lower false positive rate compared to NT measurement.

Alternatively, we use 3.5 mm (NT thickness) as a cut-off for the referral of expecting mothers to a fetal medicine unit for further counselling in accordance with NHS guidelines.

Prior to the invention of NIPT (non-invasive prenatal testing), NT thickness was the most effective screening method for trisomy 21 (Down’s syndrome).

About 8-10 years ago, we were actively involved training medical professionals (doctors and sonographers) in performing the NT assessment. As a part of this program, we had created training videos that have been uploaded to YouTube. Overtime, these videos have become one of the most popular NT videos with nearly 700,000 views.

If you click the link below, you will be able to watch these videos, although we would like you to be aware that they are old and have not been updated, because when they were created, 10 years ago, before the era of NIPT, they represented the most advanced information we had about NT measurements.

NT thickness measurements are included in the early fetal scan and can be done for free during the advanced early fetal assessment.

Please book the early fetal scan or our all-inclusive early fetal reassurance package: ultrasound scanning and NIPT working together, which is an optimal combination for excluding fetal anomalies in the first trimester (done at 10-13 weeks).

Get in touch with our team to learn more about our 12-week nuchal scans in London.