What does NT mean?

Prenatal check-up is an important item in Down syndrome screening. Through such examination, we can see whether the child will suffer from Down syndrome, especially when the pregnancy is between 11 and 14 weeks. The examination will be more accurate at this time. If the child's heart is not well developed and the nuchal translucency is thickened, this will increase the possibility of child deformity and increase the probability of fetal abnormalities.

In addition, when doing NT examination, there are several points to note:

1. NT (nuchal translucency scan) examination is a B-ultrasound examination item that does not require blood tests. Eating and drinking will not affect the test results, so there is no need to fast before the examination.

2. 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 body 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.

3. It is best to make an appointment for NT in advance. Generally, you can start making an appointment with the hospital 11 weeks before pregnancy for scheduling. Do not make an appointment after 13 weeks of pregnancy to avoid long waiting times. Doing NT after the gestational age will affect the accuracy of the test results.

The difference between NT and Down syndrome screening

Both NT screening and Down syndrome screening are used to understand the health of the fetus, so both examination methods can screen the health of the fetus at an early stage.

NT screening refers to the thickness of the nuchal translucency and the serum test of pregnant women. The nuchal translucency refers to the space where water accumulates under the skin behind the fetus' neck. During an ultrasound scan, the doctor will measure the thickness of the space between the skin and tissue in detail. The nuchal translucency will be significantly thickened in fetuses with chromosomal abnormalities, especially in babies with Down syndrome. Down syndrome is usually more likely to occur in older mothers. Medical literature has confirmed that the thicker the nuchal translucency of the fetus, the higher the chance of chromosomal abnormalities. NT screening is performed between 11 and 13 weeks of pregnancy.

Down syndrome screening is a detection method that extracts serum from pregnant women, tests the concentrations of alpha-fetoprotein, chorionic gonadotropin and free estriol in the maternal serum, and calculates the risk of giving birth to a fetus with congenital defects based on the pregnant woman's due date, weight, age, weight and gestational age at the time of blood collection. The best time to do Down syndrome screening is between 15 and 20 weeks of pregnancy.

In summary, NT is an ultrasound used to screen for trisomy 21 at around 11-13 weeks of pregnancy, while Down syndrome screening is a screening method using serum blood markers at around 15-18 weeks of pregnancy. These are examinations using different methods at different stages, and sometimes a combined examination of the two is required.