What is a nuchal scan?

Nuchal Translucency . Nuchal Translucency is a screening test to determine risk of chromosome abnormalities in a fetus. When the NT is greater than 3.5 mm, there is a 1 in 5 chance of a chromosome abnormality such as Turner or Down syndrome, or Trisomy 18. Additional tests should be ordered by an OB or genetic counselor for confirmation. A mother may decide to continue or end of the pregnancy based on the information.
Genetic screening . A nuchal translucency ultrasound measures the skin on the back of the baby's neck. This is done between 11-14 weeks gestation. Babies with down syndrome have more fluid and thicker skin at the back of their necks. This skin measurement, combined with the results of the first and second trimester genetic screen blood tests, predict the risk of having a baby with a chromosomal problem.
An ultrasound value. A nuchal scan measures the soft tissues along the back of the fetal neck during an ultrasound. Thickening of the nuchal soft tissues is associated with an increased risk of several chromosomal abnormalities and may prompt recommendations for genetic screening.