Nuchal Translucency Measurement in Early Pregnancy
Understanding Nuchal Translucency Measurement
Using ultrasound to view the fetus, nuchal translucency measurement is performed during weeks 11 to 13 of pregnancy to help assess the risk for chromosomal abnormalities such as Down syndrome.
Previously, genetic counseling and diagnostic testing for Down syndrome was typically only offered to women age 35 and over since testing required amniocentesis or chorionic villus sampling. The American College of Obstetricians and Gynecologists now recommends the non-invasive nuchal translucency measurement diagnostic test be offered to all pregnant women, regardless of age. When done in combination with a maternal blood test, nuchal translucency measurement is considered an effective screening test.
Using ultrasound, a crown to rump measurement of your baby is done to determine precise gestational age. Next, a measurement is taken to determine the thickness of the fluid under-the-skin at the back of neck. A build-up of fluid in the nuchal fold may indicate a chromosomal abnormality.
Abnormal Nuchal Translucency Measurement in Early Pregnancy
When combined with a blood sample from the mother, the accuracy of nuchal translucency measurement in early pregnancy is considered to be approximately 70 to 80 percent, but the test is not enough for a definitive diagnosis of Downs syndrome. An abnormal test does signal the need for additional testing, usually amniocentesis.
Risks Associated with Nuchal Translucency Measurement in Early Pregnancy
Since nuchal translucency measurement is performed through the use of non-invasive ultrasound, there are no known risks. The test is considered safe for both mother and baby.