There are so many tests involved with pregnancies! The first one is the ovulation test, then the pregnancy test, then the blood test…and that’s just the beginning.
There are tests you will undergo from the time you decide to start trying all the way up to delivery. Some are more uncomfortable than others (like the amniocentesis, for example) but there is one test, in particular, that provides very important information early on in the pregnancy, and it is pain free.
The Nuchal translucency test (NT) is a diagnostic tool for identifying Downs Syndrome and other chromosomal abnormalities, including congenital heart issues.
While older women are more likely to have a child with Downs, the test is performed frequently in all age groups, as it is a quality identification tool for abnormalities.
The test is a simple ultrasound, generally performed between the 11th and 13th week of pregnancy. This is the time when the tissue at the base of the baby’s neck is translucent. Very specific measurements are taken to determine the thickness of the soft tissue. A thickened Nuchal area usually signals Downs, but can point to other abnormalities as well. This test is usually done in conjunction with a blood test, and a test for the development or absence of a nasal bone. This combination of tests is called the first trimester combined screening.
If the screening is positive, that does not mean that Downs is present. The only definitive test for Downs is amnio or CVS, but both of these procedures can increase the risk of miscarriage, so the Nuchal measurement can provide important information without risks to the pregnancy. However, the Nuchal screening does correctly identify over 60% of Downs babies.
If a scan measurement does exceed the normal range, an amnio or CVS would be needed to confirm the screening.
More on CVS and amnio in my next post.
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