Nuchal Translucency / Nasal Bone

Nuchal translucency (NT) is a measurement taken during pregnancy that can be used to assess the risk of certain birth defects, such as Down syndrome. It is typically measured during the first trimester, between 11 and 14 weeks of pregnancy.

The NT measurement is taken using ultrasound, which uses high-frequency sound waves to create images of the developing fetus. The measurement is made by measuring the clear (translucent) space at the back of the neck of the fetus. A larger NT measurement can be an indication of an increased risk of birth defects, although it is not a definitive diagnostic test.

Ultrasound is also used to assess the presence and appearance of the nasal bone in the developing fetus. The nasal bone is a small bone in the nose that begins to develop early in pregnancy. The presence and appearance of the nasal bone can be an indicator of fetal health and development.

It is important to note that the NT measurement and assessment of the nasal bone are only two of several factors that healthcare providers consider when assessing the risk of birth defects. Other factors, such as the mother's age and medical history, may also be taken into account.

How to prepare for your exam. Read More →


Common Questions

First Trimester NT/NB Screen is performed when the fetal crown-rump length (CRL) measures between 45 mm and 84 mm, which correlates to 11- and 14-weeks of gestation. If the CRL falls outside these measurements then the test is invalid. For that reason, we recommend that First Trimester NT/NB Screening be scheduled at 12- to 13-weeks gestational age whenever possible.

Yes. A detailed fetal assessment performed during the NT scan can detect 30 to 60% of all congenital abnormalities. Additionally, increased NT thickness is also associated with 40% of congenital heart defects.

A baby's sex can be determined as early as week 12. However, it is not as accurate until weeks 18-20 at your anatomy scan.

At 12 weeks, male and female fetuses have a bump called a genital tubercle. The bump represents the developing genitalia. During this stage of development, the genital tubercle points either toward the head, which means boy, or toward the feet, which means girl.

As much as we hope your little one will cooperate, they may have other plans. Crossed legs, the presence of the umbilical cord between the legs, or other less-than-ideal fetal positions can prevent the sonographer from getting a good look.

girl ultrasound
boy ultrasound