NT Scans
By Alice Vandyke
If this is your first pregnancy you will probably be surprised and overwhelmed by the number of tests and scans that are available to you. However, I believe strongly that knowledge is power and the more information you can gather going into your antenatal visits, the more prepared and relaxed you will feel. As always, all medical tests and tools are optional to you.
How common is it to have an NT scan?
Not everyone has a NT scan, it has however become common practice in our health care system. The reason to have the NT scan is to be informed as early as possible if your baby is showing signs of having a chromosomal abnormality. These complications are also screened for in the routine 19 week ultrasound scan. The NT scan is also the most accurate and relied upon way to date a pregnancy now, health professionals relying less on menstrual cycle dates or the early dating scan.
Situations an NT scan is most important
The risk of Down Syndrome becomes higher as women age, thus women over the age of 35 are highly recommended to undergo a NT scan.
Why does the scan need to be done at such a precise time?
The scan is performed between 11 and 13 weeks plus 6 days gestation, because this is the most accurate time to measure the Nuchal Translucency which is a fluid filled space at the back of the baby’s neck. The fluid is increased in babies with abnormalities. After 13 weeks and 6 days the NT fluid is absorbed into the baby’s body and therefore cannot be reliably measured.
What does it cost?
NT Scans are not usually bulk billed, for the most part the scan and blood test is costed differently by each imaging company with a small rebate under Medicare. Have a look around at different imaging companies to compare prices.
What does the scan involve?
The scan is as simple as all other pregnancy scans. It involves booking in the appointment for the exact gestation, drinking 2 glasses of water to push the baby into the best location in your uterus and having the ultrasound probe go over your lower abdomen. Sometimes the baby can be so low in the uterus, that the best way to see them accurately is through the vagina. This is of course, like all medical procedures, optional. A vaginal ultrasound involves the insertion of a separate ultrasound probe into the vagina with lubricant, to allow a view of the baby through the vagina and cervix and into the uterus. The NT scan can be done alone; however it is more informative accompanied by a blood test. The maternal blood is analysed to see the baby’s blood cells that are mixed within it. The baby’s blood is then genetically screened for the chromosomal abnormalities the scan is looking for.
What is the scan screening for?
Genetic abnormalities including Trisomy 13, 18, or 21. Otherwise known as Downs Syndrome, and the rarer Edwards’ Syndrome and Patau’s Syndrome.
How long does it take to receive my results?
The results are usually given to you at your next antenatal appointment, however if the results are complicated then your health professional will contact you sooner.
What if the results are complicated?
A NT Scan is a screening tool, not a diagnostic test. What this means is that the results give a ratio of how likely your baby is to have a chromosomal abnormality. Whereas a diagnosis gives you a yes or no answer. If the results come back with a high ratio, further testing will be recommended. However, even a ratio of 1:10, means that 1 out of 10 babies will have Downs, and 9 will be born healthy. The next test that will be recommended if you have a high risk NT scan result, is an Amniocentesis, “Amnio” coming from the Amniotic fluid, or waters around the baby. This test is diagnostic, however is associated with a minor risk of further complications, which is why it is only recommended with a concerning NT.
A NT Scan is just one of a myriad of tests you will be offered throughout your pregnancy, which is used to give you the best information about yours and your baby’s health and well-being. Always remember tests are optional and if you feel uncomfortable or anxious, it’s always a good idea to discuss your concerns with your care giver.