Nuchal translucency Scan is a test used to predict those women who are at high risk of having a baby with chromosomal abnormalities such as Down syndrome, trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome). This screening test does not diagnose a chromosomal abnormality, but may identify those who are at greater risk, compared to other women of the same age. The test involves a specialised ultrasound scan combined with the results of a blood test that measures the amount of two pregnancy hormones. The nuchal translucency ultrasound can only be performed between 11 weeks’ + 3 days’ gestation and 13 weeks’ + 6 days’ gestation.
Empty bladder 90 mins prior to appointment, drink 500ml of water over the next 60 mins and hold.
Book at 12 weeks 4 days preferably.
What happens during the procedure
You will be asked to lie on the examination bed. Ultrasound gel will be applied to the lower abdomen and the sonographer will slide and rotate the transducer over this area, creating images of the fetus on the screen. The sonographer will assess the size and number of the fetus and the presence of a heartbeat. The sonographer will carefully assess the thickness of the nuchal translucency. The established criterion for accurate measurement is strict, so the scan may take some time. Occasionally the position of the fetus can make the measurement of the nuchal translucency difficult. In such a case, another scan may need to be performed later in the day, or on a different day.
Sometimes, with your consent, a transvaginal ultrasound may be necessary, using a specifically designed thin probe gently inserted into the vagina. This usually produces clearer images of the developing pregnancy as the probe lies very close to the pelvic organs. A protective, disposable sheath covers the transvaginal probe, which is sterilised. There is no risk to the mother or the fetus during a transvaginal ultrasound. Your height and weight will be measured before or after your scan.
How long does it take?
Usually the scan takes between 30-60 minutes to complete.
After your examination
Specialised software developed by the Fetal Medicine Foundation, will be used to calculate the risk of Down Syndrome and other chromosomal abnormalities, including trisomy 13 and trisomy 18. The individual adjusted risk for your pregnancy is calculated according to your age, gestational age of your baby, the measurement of the nuchal translucency, the presence or absence of the fetal nasal bone and your blood test results. This may be higher or lower than your background risk. A risk greater than 1 in 300 is high and further testing may be required.
Your images and report
After your examination, you will be given a copy of the most pertinent images from your study. A report will be given to you with the images, or sent directly back to your referring doctor by fax or email. PRP will store digital copies of all studies on our secure database for comparison with any future examinations.
Please bring any previous images with you for comparison.
It is important that you return to your doctor with your examination results. Whether they are normal or abnormal, your doctor needs to know promptly so that a management plan can be formulated.