24th March 2010 22:12
We had it on this pregnancy, didn't on DS as we were away during the timeframe in which you have to have it done. It's totally non-invasive, just like a normal scan. They'll measure the thickness of the skin at the back of the baby's neck & look for other markers that could indicate Down's Syndrome or other trisomies - like the presence of a nasal bone, position of the ears, formation of the skull, heart development. You'll then get some bloods taken - just from your arm and the blood test results combined with the scan results will give you a 1 in something chance of having a Down's baby or a baby with another condition such as Edward's Syndrome. Your results will be compared to what is a typical risk for your age (it's 1 in 500 for a 31 year old - me) and your doctor will then discuss them with you. If you have a very high risk there are further tests that can be done to actually determine if your baby has any of these conditions, the nuchal scan is just a risk determination, not a diagnosis.
HTH x