What is nuchal translucency measurement?

This prenatal screening test uses ultrasound to measure the clear ("translucent") space in the tissue at the back of your fetus's neck. The measurement is performed between 11 and 14 weeks of pregnancy.

Why is it performed and how does it work?

The measurement can help assess your baby's risk for Down's syndrome and other chromosomal abnormalities. All developing babies have a layer of tissue on the back of their body between the skin and the underlying soft tissue.

This layer is black or translucent on ultrasound and its thickness is measured at the neck. After combining the nuchal translucency measurement with your age, and other factors, we can calculate your risk of having a baby with a chromosomal abnormality for this pregnancy. Babies with abnormalities accumulate more fluid at the back of their neck during the first trimester, causing this clear space to be larger. The nuchal translucency (NT) screening test won't give you a definite diagnosis, but it can help you decide whether you want to undergo diagnostic testing. NT is painless and involves no risk to the pregnancy.

During this ultrasound scan, subject to the age and position of the fetus, we are able to:

• confirm you are pregnant
• determine if the fetus is alive
• confirm gestational age
• identify multiple pregnancies
• identify some abnormalities.

			Pre Examination
	Please phone us to make an appointment for your NT ultrasound.

			The Examination
	Preparation for your scan You will need a full bladder. One hour before your scan, please empty your bladder and drink one litre (4 glasses) of water. The NT scan is done by placing an ultrasound probe on your abdomen. In some cases it may be necessary to perform the scan internally using a trans-vaginal probe. The scan will take approximately 15 minutes, and is performed by a sonographer or radiologist.

			Post Examination
	We will send a report on your scan to the person who referred you for your ultrasound. If your scan suggests you are at an increased risk, then you should discuss this result with your referring practitioner. This does not necessarily mean the baby is abnormal, but indicates further tests may be required. Most fetuses given a high risk will, in fact, be proven to be normal on further testing. Your doctor or midwife will be able to give you advice about options for further testing, such as chorionic villus sampling (CVS) and amniocentesis.