Nuchal Translucency Ultrasound

This is usually the anxious time for parents while they wait for the ultrasound to check on their baby. We will do our best to answer your questions and minimize your anxiety.

WHAT IS A NUCHAL TRANSLUCENCY ULTRASOUND?

A nuchal translucency ultrasound which is commonly called a "Nuchal Scan" or "NT Scan") is an ultrasound performed between 11.6 and 13 weeks, 6-day gestation. It is usually part of an assessment called Combined First Trimester Screening.

WHAT IS COMBINED FIRST TRIMESTER SCREENING?

bnormalities (Trisomy 13, 18 and 21). This testing combines the nuchal translucency ultrasound with specific blood tests. Nuchal translucency ultrasound can also provide this risk assessment; however, it is not as accurate as combined first trimester screening.
Using the nuchal translucency ultrasound alone will detect 80% of babies with Down syndrome.
Using combined first trimester screening (ultrasound and specific blood tests) will detect 90% of babies with Down syndrome.
Combined first trimester screening is a non-invasive way of assessing your risk, which means it does not involve putting needles into the placenta or amniotic sac, as happens with CVS and amniocentesis.
Combined first trimester screening is a "screening" test only. This test tells us if your risk is low or high, whether the baby has a low or high risk of having trisomy 13, 18 or 21. This test gives us an indication of whether we should do or not further tests.
Combined first trimester screening does not give a 100% answer.
To get a definitive answer for chromosome abnormalities including Down syndrome, a prenatal diagnostic test are needed (chorionic villus sampling or amniocentesis). Chorionic villus sampling and amniocentesis are invasive tests, involving putting needles into the placenta or amniotic sac, and they are associated with 1% risk of miscarriage.