Why do you have a nuchal fold scan?
The nuchal fold scan is an ultrasound test that checks the amount of fluid beneath the skin of the baby’s neck. Babies with Down’s syndrome (a chromosomal disorder) often have a thicker layer than babies who do not have Down’s syndrome. The sonographer will also look to see if the baby’s nasal bone is present or shortened as this can also be a marker for foetal abnormalities.
What do the blood tests tell you?
At your Nuchal fold scan the blood tests measure the amount of HCG and PAPP-A protein in your blood. High levels of HCG twinned with low levels of PAPP-A can mean the baby has a chromosomal abnormality such as Down’s syndrome.
Although the nuchal fold scan can identify approximately 75% of babies with Down’s syndrome, around 5% of normal babies also receive high risk markers.
What can you see at the nuchal fold scan?
Although it’s possible to see the heartbeat and measure the foetus at earlier scans, this is the first chance for you and the sonographer to see the baby in greater detail. You should be able to see the whole body of the baby - the head, arms, legs, hands and feet, and the sonographer will be able to examine the placenta, amniotic fluid, and umbilical cord. You may also be able to see the baby make movements and wave its arms and legs about. You may be offered pictures printed out from the scan that you can take home with you.
If there are any major abnormalities in your growing baby the sonographer will usually be able to identify them at the nuchal fold scan.
How reliable is a nuchal fold scan?
In every 1,000 babies born in the UK, one will be affected by Down’s syndrome. From the nuchal fold scan alone about 75% of cases are correctly identified, but when combined with the blood test the success in predicting Down’s syndrome risk rises to about 90%.
What should I do if my risk is high?
Many women who receive a high risk result at their nuchal fold scan go on to have healthy babies, however the older the mother the greater the risk factor.
If your nuchal translucency scan identifies that your baby is at a high risk of having Down’s syndrome, other diagnostic tests are available that can tell you for sure. These tests are more invasive and carry about a 1% risk of miscarriage. A CVS (chorionic villous sample) test can be done at 12 weeks and or you can wait until week 16 and have an amniocentesis.
Profile of the author
Jackie Griffiths writes journal and newsletter articles for companies and non-governmental organisations across the UK. As founder and senior writer at Freelance Copy, she writes top level content for websites and print across a broad range of sectors including health, medical, biological, governmental, and pharmaceutical.