The nuchal (say "NEW-kuhl") translucency screening is a test done during pregnancy. It uses ultrasound to measure the thickness of the fluid buildup at the back of the developing baby's neck. If this area is thicker than normal, it can be an early sign of Down syndrome, trisomy 18, or heart problems.
The test is done between 11 and 14 weeks of pregnancy. It may be done as part of the first trimester screening test or the integrated screening test.
This test shows the chance that a baby may have a certain problem. It can't show for sure that a baby has a problem. You would need a diagnostic test, such as chorionic villus sampling (CVS) or amniocentesis, to find out for sure if the baby actually has a problem.
Why It Is Done
A nuchal translucency test is done to find out the chance that your developing baby (fetus) may be at risk for having Down syndrome or other problems.
How To Prepare
You may need a full bladder for the nuchal translucency test. If so, you'll be asked to drink water or other liquids just before the test and to avoid urinating before the test.
Talk with your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
Most often, a nuchal translucency test is done by a specially trained ultrasound technologist. But it may be done by a radiologist or an obstetrician who has received special training to do this test.
Often you don't need to remove your clothes for the test. You can lift your shirt and push down the waistband of your skirt or pants. If you're wearing a dress, you'll be given a cloth or paper covering to put over your legs during the test.
If you need a full bladder for the test, tell your doctor or ultrasound technologist if your bladder is so full that you're in pain.
During the test:
- You'll lie down on your back or on your side on an exam table.
- A gel will be spread on your belly.
- A small, handheld device called a transducer will be pressed against the gel on your skin and moved over your belly. Images of the baby are displayed on a monitor. The technologist or doctor will look for and measure the thickness of the fluid buildup at the back of the baby's neck.
When the test is done, the gel is wiped off your skin. You can urinate as soon as the test is done.
The test usually takes about 15 to 20 minutes.