Nuchal Translucency Screening

Nuchal Translucency Screening

What is the Nuchal Translucency?

All fetuses have a small fluid layer under the skin at the back of the neck. This is called the nuchal translucency. It has been found that 80% of fetuses with Down Syndrome will have thickening of this layer of fluid when compared with the normal fetus. Thickened fluid can also be associated with cardiac problems and some less common syndromes. However a vast majority of fetuses with a thickened layer of fluid will be normal.

Nuchal Transluceny Screening 

Measuring the nuchal transluceny thickness by ultrasound scanning is a screening test, and when combined with the age of the mother and particular biochemical markers within the mother's blood, it provides an estimate of the risk of the fetus having Down Syndrome. If the risk is greater than 1:300 you will commonly be offered the option of undergoing diagnostic needle tests. These include chorionic villus sampling and amniocentesis, performed by an obstetrician. These tests are highly accurate in the diagnosis of Down Syndrome, but they are invasive and carry a risk of miscarriage in about 1% of women undergoing the procedure. 

When is Nuchal Transluceny Screening Performed? 

This must be performed between 11+2 and 13+6 weeks gestation as the measurements have not been shown to be as effective outside this range. The blood test must be performed between 9 and 13 + 6 weeks gestation. When Canterbury Health Laboratories have received both the blood test and the nuchal translucency scan result, they will calculate your risk assessment and provide this information to your lead maternity carer. If the gestation is too early a further booking will be recommended. If it is too late a further blood test in the second trimester along with your anatomy scan can be helpful. 

Nuchal Transluceny screening at CRG 

CRG uses high resolution ultrasound machines. The scan will be performed by an accredited sonographer who will be happy to discuss any concerns or questions you might have.

Remember it is your decision whether or not to undergo nuchal transluceny screening.

Julie Beaumont

Clinical Specialist Sonographer