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Shedding light on the nuchal translucency ultrasound

Anne-Maude Morency

The Society of Obstetricians and Gynaecologists of Canada recommends this prenatal screening test for all women between the 11th and 14th weeks of pregnancy. One of the primary goals of this scan is to determine the risk of chromosomal abnormalities such as trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome). This ultrasound is then often combined with a blood test (Québec Prenatal Screening Program or cell-free DNA screening), which increases the accuracy of the screening for chromosomal abnormalities.

How a nuchal translucency ultrasound provides useful data for prenatal care:

  • One of the first steps of this ultrasound is to confirm the viability of the fetus. Since the period between the 11th and 14th weeks may coincide with a decrease in pregnancy symptoms, this test tries to initially determine the number of fetuses and visualize their cardiac activity.
  • An accurate dating of the pregnancy is done by measuring the length of the fetus, and is sometimes done between the 7th and 11th weeks of pregnancy. If a nuchal translucency ultrasound is performed, it is usually not indicated to change the estimated date of delivery established by the dating ultrasound.

Nuchal translucency is the accumulation of fluid normally present behind the neck of a fetus. It can only be measured during a limited gestational window, when the fetus is 45 to 84 mm long. When nuchal translucency is higher than normal, the risk of Down syndrome and other malformations, including heart defects, is higher. In such cases, a consultation with an obstetrical care professional is required. It should be noted that a high nuchal translucency measurement does not mean the baby is “abnormal.” You should discuss this with your doctor or midwife, who will be able to evaluate all the available data and inform you of the options available to you and your partner.

Consult our Neat Little Guide on pregnancy to learn about issues that could affect you, potential fetal abnormalities, and the medical tests that can detect them.

Imagix™ is a reliable partner for your obstetric ultrasound examinations. Our highly qualified staff has extensive expertise and experience in the field. Imagix adheres to the principles set forth by Health Canada and encourages the performance of obstetric ultrasounds for medical purposes.

Has your doctor prescribed an obstetrical or nuchal translucency ultrasound? Find out more about the Prenatest® available at Biron.

Anne-Maude Morency