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. The test usually takes about 15 to 20 minutes. How It Feels During a nuchal translucency test, you may have a feeling of pressure in your bladder. Risks There are no known risks linked with a nuchal translucency test, either to you or the baby.
Results Your doctor will look at the results of the nuchal translucency test to see if the area at the back of the baby's neck is thicker than normal. Nuchal translucency test footnote 1 Normal: 2. How accurate is the test? The accuracy of this test is based on how often the test correctly finds a problem.
For example: The nuchal translucency test correctly finds Down syndrome in 64 to 70 out of fetuses who have it. It misses Down syndrome in 30 to 36 out of fetuses. But these tests miss it in 13 to 18 out of fetuses. This means that the test misses Down syndrome in 4 out of fetuses. What Affects the Test Nuchal translucency test results may be affected by: Being overweight or obese.
Stool feces or air in the intestines or rectum. An abnormally low amount of amniotic fluid. Not being able to lie still during the test. The fetus being in certain positions during the test. A very active fetus. NT results by themselves have an accuracy rate of about 70 percent. That means that the test misses 30 percent of babies with Down syndrome or other chromosome disorders.
Including the NT as part of a first trimester combined screening improves detection to between 83 and 92 percent. Pairing the results of the nuchal translucency with other screening tests in the first trimester further improves the accuracy. The integrated screen, which combines the NT screening, measurements of the hormone PAPP-A, and the quad screen , improves Down syndrome detection rates to between 94 and 96 percent. If your nuchal translucency screening or any other prenatal screening results indicate that your baby may be at an increased risk of having a genetic abnormality, your practitioner will likely suggest a diagnostic test like chorionic villus sampling CVS or amniocentesis.
He or she may also suggest talking to a genetic counselor, who can better explain what the results mean. An abnormally thick nuchal measurement should be taken into account at the week anatomy scan and special attention paid to scanning the heart. Increased NT measurements may also be linked to a very slightly higher risk of preterm birth , so you may be monitored for that as well. Keep in mind that all pregnancy screenings, including the nuchal translucency and the associated bloodwork, don't directly test for chromosomal problems.
An abnormal result on the nuchal translucency or combined screening test doesn't mean that your baby has a chromosomal abnormality. They just mean that there's a statistical likelihood of having a problem. Try not to overthink your results. Many women who have an abnormal result on their screening test go on to have a perfectly normal, healthy child.
Also keep in mind that a normal result on a screening test is not a guarantee that your baby does not have a chromosomal defect, although it does mean that it's very unlikely. The person performing the NT scan may also ask you to drink a glass of water before you begin.
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How to get a NT ultrasound If you choose to have a NT ultrasound, your health care provider will arrange it for when you are 11 weeks 2 days to 13 weeks 3 days gestation. Zoom in to locate a NT ultrasound facility near you.
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