When is the best time to check NT?

The NT test is a very important test for pregnant women because it can effectively detect whether the fetus has chromosomal abnormalities. The most direct consequence of chromosomal abnormalities is Down syndrome, so the NT test is also a Down syndrome screening test in a sense. However, not every period of pregnancy is suitable for NT examination. So when is the best period of pregnancy to do NT examination?

How many weeks of pregnancy is best to do nt

Because the fetus is too small to observe the nuchal translucency before 11 weeks of pregnancy, and the fetus gradually develops after 14 weeks of pregnancy, it may absorb excess fluid from the nuchal translucency and affect the test results. Therefore, it is best for pregnant women to do NT within 11-14 weeks of pregnancy to avoid inaccurate test results.

A nuchal translucency scan is usually performed between 11 and 14 weeks of pregnancy. It is technically difficult to perform an NT scan before 11 weeks because the fetus is still too small. After 14 weeks, the water accumulated under the fetus's skin may be absorbed by the developing lymphatic system, making it impossible to obtain accurate test data. Therefore, pregnant women need to go to the hospital for NT examination within 11-14 weeks of pregnancy. Generally, nuchal translucency scan can be performed in tertiary hospitals or large specialized obstetrics and gynecology hospitals.

Why do we need to do Down syndrome screening after NT examination?

The NT test is to make an early diagnosis by screening the thickness of the fetal nuchal translucency to determine whether the fetus has any abnormalities. If the thickness of the nuchal translucency exceeds 3mm, it may indicate that the fetus has a chromosomal disease or is dysplastic.

Down syndrome screening is performed by drawing 2 mm of venous blood from the pregnant mother. This is a non-destructive testing method for the fetus and is usually performed between 14 and 18 weeks of pregnancy. If the serum screening result is positive for the pregnant mother, an amniotic fluid test will be required to clarify the diagnosis and treatment methods. Down syndrome screening can also detect pregnant women at high risk of neural tube defects, 18-somy syndrome and 13-somy syndrome.

Therefore, when doing NT screening, if the gestational age and the baby's condition are suitable, the doctor will also recommend pregnant mothers to do Down syndrome screening to prevent the disease before it occurs.

Sometimes women are pregnant, but sometimes some women don’t know what problems they should check. Sometimes I don’t even know when to have a physical examination. Of course, the NT examination is a particularly important examination because it can check the nuchal translucency. This test is usually done around three months into the pregnancy because the fetus has not yet formed.