The NT scan aka Nuchal Translucency Scan
Are you feeling a little nervous about your upcoming NT scan? Don’t worry, I’m here to guide you through it and help you understand what to expect.
The NT scan, also known as the nuchal translucency scan, is a special ultrasound that’s typically performed between 11 and 14 weeks of pregnancy. During the scan, the thickness of the skin at the back of your baby’s neck is measured. This measurement, along with some other factors, can give healthcare providers important information about your baby’s health.
While the thought of any medical procedure can be scary, the NT scan is a completely safe and non-invasive test. It’s a chance for you to get a closer look at your growing baby and make sure they’re developing as expected.
What is the NT scan?
A nuchal translucency scan is an ultrasound scan that measures your baby’s nuchal translucency — a fluid-filled space behind your baby’s neck. This measurement can help your doctor estimate the risk of your baby having a chromosomal abnormality such as Down syndrome.
Should I have a nuchal translucency scan?
The chances of having a baby with a chromosomal abnormality are greater the older you are when you get pregnant. However, anyone can have a baby with chromosomal abnormalities, so screening is offered to everyone, but the decision to have the scan is yours.
While scans can reassure you that your baby is developing normally, you may also learn that your baby has an abnormality.
For this reason, before you have the test it’s a good idea to think about why you are choosing to do it, and what you would do next if your screening test showed you were at a high risk of your baby having a chromosomal abnormality.
Some women choose not to have any tests or decide to have a diagnostic test instead (like the NIPT test, next lesson), which can give you more definite information about your baby’s health.
When is a nuchal translucency scan done?
A nuchal translucency scan is done between 11 and 14 weeks of pregnancy.
How is a nuchal translucency scan done?
In early pregnancy, ultrasounds such as the nuchal translucency scan can be done through your abdomen or vagina. Your sonographer will choose a method based on several considerations, including how far along your pregnancy is and your body shape.
If your scan is done along your abdomen — transabdominally — you will be asked to drink a few cups of water before you arrive so that your bladder is full. This makes it easier to see inside your uterus (womb). The sonographer will apply some gel and gently move the ultrasound probe across your abdomen. It doesn’t usually hurt.
If your scan is done transvaginally, a small, lubricated ultrasound probe is gently inserted into your vagina. The probe may be a little uncomfortable but usually isn’t painful. Scans done this way can give more detailed pictures because the probe is closer to your uterus.
Ultrasounds do not harm you or your baby or increase your risk of miscarriage.
What do the results mean?
This is a screening test, so the results can’t tell you for sure whether your baby has a chromosomal abnormality. If your test returns a high-risk result, you may decide to have a diagnostic procedure such as chorionic villus sampling, amniocentesis or the NIPT which can give you a definitive result.
Results are usually reported as ‘low risk’ or ‘high risk’.
Low risk is fewer than 1 in 300 tests would indicate risk of chromosomal abnormality (for example, 1 in 450 tests); high risk is greater than 1 in 300 would indicate risk of abnormality (for example, 1 in 150 tests).
Your nuchal translucency scan results can be combined with a blood test, usually done in weeks 10 to 12 of pregnancy, to form a ‘combined first-trimester screen’, or CFTS. The combination of blood test and ultrasound results can give a more accurate estimate of your risk.
During the test, the sonographer may also:
confirm that your pregnancy is in the right place and is not ectopic
look for your baby’s heartbeat
check if you are carrying more than one baby