NT SCANS - FREQUENTLY ASKED QUESTIONS
1. WHAT IS NUCHAL TRANSLUCENCY(NT) SCAN? WHAT IS THE PURPOSE?
It is an important scan done between 11 and 14 weeks.
In addition to dating and confirming fetal viability, an NT scan picks up major congenital anomalies and assess markers for genetic anomalies.
2. DO I REALLY NEED NT SCAN OR GENETIC SCREENING? WHAT IS A COMBINED TEST?
Even though the risk for fetal genetic anomalies is highest above the age of 35, it is found that more than 70% of babies with genetic abnormalities are born to younger mothers. Therefore, it is essential to assess the risks for every pregnancy.
In addition to maternal age, factors like structural abnormalities, nuchal translucency (NT), presence of Nasal bone, Tricuspid valve regurgitation, Ductus venosus flow which is assessed by a detailed NT scan are helpful to get a final risk score.
In addition to NT scan, a double marker test is done, where 2 components of maternal blood are assessed. This combination of NT scan and double marker test is called a Combined Test, which has an accuracy of 95% compared to 30% when considering maternal age alone.
3. ULTRASOUND AND BLOOD TESTS - ARE THEY SAFE?
Ultrasound scans are perfectly safe in pregnancy. Ionising radiations are not emitted by ultrasound systems, unlike X-rays and CT scans. In fact, ultrasound is the recommended modality for assessment in pregnancy.
Taking Mother's blood for these tests is not at all harmful for the fetus. We require only a small amount of blood for these tests.
4. IS IT ESSENTIAL THAT BLOOD TESTS MUST BE DONE ON THE SAME DATE AS THE NT SCAN?
Yes, it is. Fetuses grow at a rapid rate and the crown-rump length and NT changes every day. Therefore, the tests must be done on the same day, for the most accurate results.
5. IF THE COMBINED TEST RESULTS ARE NORMAL, WHAT SHOULD I DO NEXT?
If the combined test results are normal (Low risk), the risk for genetic anomalies for the fetus is low. However, it is difficult to rule out all structural anomalies at this time.
A detailed anomaly scan should be done at 5 months to rule out major structural anomalies. A complete evaluation of the heart and brain is done during this scan.
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6. IF THE COMBINED TEST RESULTS ARE ABNORMAL, WHAT SHOULD I DO NEXT?
A combined test is used for screening purposes, to determine whether the fetus has a high or low risk for genetic defects. Therefore, only a probability for genetic abnormalities is obtained.
To confirm the presence of a genetic anomaly, to characterise it and to assess the risk in subsequent pregnancies, further tests must be done, which will be discussed with you by the doctor.
7. WHAT SHOULD I DO IF I MISSED THE COMBINED SCREEN TEST?
Combined screening is the most accurate among the screening tests (95%) and should be done before 14 weeks. If a combined screening is missed, it is possible to opt for a Quadruple screening test which is done from 16 weeks onwards. The accuracy of this test is around 80%.
8. ARE THESE TESTS AVAILABLE EVERYWHERE?
These tests are available only in specialised fetal medicine centres. Measurements for the assessment of genetic anomalies have to be precise and according to international standards. Special training is required to accurately evaluate the fetus. Deviations in measurements can lead to variable results and unnecessary invasive procedures. Our doctors have FMF accreditation are trained for advanced scans and have years of experience in the field.
Quality control of the laboratory is also of utmost importance for reliable results. We at Soorya Diagnostics make use of the best laboratories in the country to get the most accurate results.