What does non-invasive NT test check?

Non-invasive NT test is a test that pregnant women must undergo during pregnancy. It is mainly used in the early stages of pregnancy to determine whether the fetus has chromosomal abnormalities. In the second trimester of pregnancy, Down syndrome screening and non-invasive DNA tests are generally performed. Although their tests are more expensive, they are preventive for both pregnant women and fetuses. So what is non-invasive NT test?

NT test

NT refers to the "nuchal translucency", which is the maximum thickness between the skin and subcutaneous soft tissue on the horizontal sagittal surface of the fetal cervical spine. The NT examination is aimed at measuring this indicator. The nuchal translucency is a collection of fluid under the skin at the back of the baby's neck during weeks 11-13+6 of pregnancy and can be measured using ultrasound. The purpose of the nuchal translucency test is to diagnose chromosomal diseases and detect fetal abnormalities caused by various reasons in the early stages of pregnancy.

Non-invasive DNA

Non-invasive DNA testing directly sequences and analyzes free fetal DNA in the peripheral blood of pregnant women. It is a safe, accurate and rapid new technology for detecting fetal chromosomal diseases. This technology only requires drawing venous blood from the pregnant woman to accurately determine whether the fetus suffers from chromosomal diseases such as Down syndrome, Edwards syndrome, and Patau syndrome. The best testing period is 12-24 weeks of pregnancy.

Purpose of testing

The main purpose of NT testing is to screen whether the fetus has chromosomal abnormalities in the early stages of pregnancy. If the NT value is greater than 3 mm, the next step of examination should be carried out in time, that is, non-invasive DNA testing, in order to more accurately judge chromosomal diseases.

Inspection period

The NT test is usually performed around 12 weeks in the early stages of pregnancy. If it is performed together with the early Down syndrome screening at this time, the screening rate can be improved. The non-invasive DNA test is performed after the NT test or Down syndrome screening is abnormal, that is, it is performed before the NT test and after the non-invasive DNA test.

Inspection method

The NT test is to check the thickness of a transparent layer on the fetus' neck through B-ultrasound. The normal value is less than 3 mm. The non-invasive DNA test is to extract the fetus' cells from the pregnant mother's peripheral serum and use advanced technology to analyze whether the fetus's chromosomes are abnormal, such as detecting trisomy 21, trisomy 18 and trisomy 13.