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Nuchal Fold Testing for Down Syndrome

Nuchal Fold Testing for Down Syndrome is a special test designed to identify if an unborn baby may have a genetic condition called Down Syndrome. This article offers information on what Nuchal Fold Testing is and other interesting testing facts.

What Is Down Syndrome?

Down Syndrome (DS) is a genetic condition. It results when a person has an extra copy of chromosome 21, giving him or her 47 chromosomes instead of the normal 46. As a result of the extra chromosome, the development of the person’s body and brain are different than they would normally be.

What Is Nuchal Fold Testing?

Nuchal fold testing - also known a nuchal translucency screening, nuchal fold scan, or NT - is a means of assessing the risk of an unborn child having Down Syndrome. Nuchal fold testing was first performed in the United States in 1995, and it was first available only at major medical centers.

Performing the test requires special training and special equipment over an above the usual training of a sonographer (ultrasound technician). Certification is offered by the Fetal Medicine Foundation in London, which is the international standard-setting organization and provider of the software used for the assessment. As more personnel are trained and certified, the test is offered more widely. If it is not available at your local hospital, it may still be done at another hospital in your area.

Nuchal Fold Testing Facts

Here are some facts about the testing:

• Besides helping assess the risk of Down Syndrome, the test also helps assess the risk of certain other abnormalities of the chromosomes and serious congenital heart issues.

• The test must be done between the 11th and 14th weeks of pregnancy. It’s commonly offered as part of a first-trimester screening along with a blood test.

• The test involves taking a measurement of an area on the back of the in-utero baby’s neck. Because babies who have chromosomal abnormalities or a few other issues are more likely to have a fluid accumulation at this spot during the first trimester, a measurement in that time period provides an initial indication of whether or not there is risk.

• The test is non-invasive: it is done with ultrasound. The sonographer begins by measuring the baby from crown (top of the head) to rump (bottom) to confirm the baby’s age. This ties into the requirements for the limited time during which the test can be performed. When that is confirmed, the ultrasound sensor is held over the baby’s neck area shows up on the monitor. The nuchal fold measurement is done on the monitor using an instrument called calipers.

• The results of the test include the nuchal fold measurement, the baby’s gestational age as confirmed by the measurement, and the age of the mother. In a combined screening, a blood test will be done as well. The mother’s age is a factor because the risk of chromosomal problems increases with age. There is a nearly 16 times greater chance for a woman who is 40 to have a baby with Down Syndrome than there is for a woman who is 20.

• Although the nuchal fold test does not provide definitive information, parents can use it to assist them in deciding if they wish to have further testing (such as amniocentesis or chorionic villus sampling, also called CVS) performed. Because both these tests are invasive, they bring a higher (though small) risk of miscarriage than NT.

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