The nuchal translucency test (also called the NT scan), it is to use ultrasound to assess your developing baby's risk of having Down syndrome (DS) or some other chromosomal abnormalities, as well as major congenital heart problems. It's offered to all pregnant women, along with a blood test called NIPT, in first-trimester combined screening options. The NT scan must be done when you're between 11 weeks and 13 weeks and 6 days pregnant, because this is when the base of your baby's neck is still transparent.
The NT scan measures the clear space in the tissue at the back of your baby's neck. Babies with abnormalities tend to accumulate more fluid at the back of their neck that is why this clear space to be larger than average in abnormal babies.
The non-invasive prenatal test, or NIPT, is a new, highly sensitive test that screens for Down syndrome and certain other abnormalities in a baby that is done in the first trimester of pregnancy. When combine with NT scan, the result is more accurate.
The NT scan and NIPT test are screening tests, they are not invasive, and not conclusive. Diagnostic testing such as CVS or amniocentesis are necessary to confirm a positive screen result when needed.
