As a pregnant mother, it is necessary to undergo various prenatal examination items during pregnancy. These examination items are mainly for doctors to better understand the physical condition of the pregnant mother during pregnancy, whether she is in good condition, and to help detect pregnancy complications as early as possible. At the same time, they can also know the development of the fetus in the abdomen and detect malformed infants in a timely manner. Some pregnant mothers have asked whether they still need to undergo Down syndrome screening after passing the NT test?
The best time for nt examination is between 11 to 13 weeks of pregnancy and 6 days of pregnancy. NT examination is an early prenatal screening item for Down syndrome. The thickness of the zona pellucida in the neck of the fetus can be checked by ultrasonic examination, which can early diagnose whether the fetus has chromosomal abnormalities. If the nt examination results exceed 3mm, it indicates that the incidence rate of fetal malformations and the incidence rate of chromosomal abnormalities will increase significantly.
Due to the fact that NT examination is only an imaging examination using ultrasound methods, the accuracy of this examination is not 100%. Even if NT examination is passed, it cannot completely rule out Down syndrome. Therefore, after NT examination is passed, it is still necessary to undergo Down screening examination. Down screening tests the blood of pregnant women to detect the concentrations of AFP, HCG, and free estriol in their serum, in order to determine the risk factor of Down syndrome in fetuses.
If the results of the Down syndrome screening are normal, then the pregnant mother can rest assured. However, if the results of the Down syndrome screening are high-risk, further screening is needed, such as non-invasive DNA or amniocentesis. Non invasive DNA is extracted from the peripheral blood of the pregnant woman to detect fetal free DNA, while amniocentesis is performed under real-time ultrasound monitoring, using a fine needle to penetrate the amniotic cavity through the pregnant woman's belly and extract an appropriate amount of amniotic fluid to check chromosomes.
