Now a woman is pregnant and gives birth to a child, which is the top priority of the whole family, in order to have a healthy baby, from the beginning of pregnancy to do a variety of tests. Especially after the second trimester, what Down's screening, four-dimensional, glucose tolerance, etc., pregnant mothers can not dare to be less.
When Down screening is done at about 12 weeks, or four-dimensional ultrasound at about 20 weeks of pregnancy, and there is something wrong with one indicator, the doctor may recommend amniocentesis or noninvasive DNA testing. Many people still have concerns about amniocentesis, but they can choose non-invasive DNA testing and do not quite understand whether it is accurate or not.
The optimal time for noninvasive DNA testing is 12 weeks gestation - 22 weeks gestation + 6 days. If the duration of pregnancy has exceeded the upper limit of 23 weeks, the risk of testing increases. If the gestational age is less than 12 weeks, it can also affect the accuracy of the screening results. Therefore, the best time to do noninvasive DNA prenatal testing is 14-18 weeks of pregnancy.
Noninvasive DNA testing is mainly used to detect certain congenital genetic disorders or chromosomal abnormalities, but also to detect certain malformations.
There are first- and second-generation noninvasive DNA tests:
A generation of noninvasive DNA testing can calculate the risk rate of fetal trisomy 21, trisomy 16, and trisomy 13. It has the highest accuracy in detecting trisomy 21,99%, 95 to 98% in detecting trisomy 18,00% in detecting trisomy, and up to 90% accurate in detecting trisomy 13-trisomy.
The goal of a generation of noninvasive DNA testing is consistent with Down screening, but the accuracy and comprehensiveness of noninvasive DNA is higher than that of Down screening. But for micro-fragmentation, micro-repetition, partial monomers and trisomy can not be tested.
The detection range of the second generation of non-invasive DNA is very wide, 17 kinds of fetal chromosome aneuploidy can be detected, which is an upgraded product of the first generation of non-invasive DNA, an advanced product based on the non-invasive DNA prenatal testing project, which increases the sequencing depth and can detect most of the chromosomal aneuploidy, chromosome micro-deletion and micro-repetition. But even so, noninvasive testing still can't rule out all chromosomal problems.
For micro-fragmentation, micro-repetition, partial monomers and trisomy cannot be tested. The second generation of noninvasive DNA can detect 10 chromosomal genetic diseases, is an advanced product based on the non-invasive DNA prenatal testing program, enhances the depth of sequencing, and successfully completes the leap of careful examination from chromosomal aneuploidy to noninvasive chromosomal micro-mutilation and micro-repetitive syndrome.
Amniocentesis is a method of prenatal diagnosis that can examine the 23 pairs of chromosomes of the fetus with relatively high accuracy. Amniocentesis is a form of diagnosis, while noninvasive DNA is a means of screening. If the noninvasive DNA test is positive, further amniocentesis is required to confirm the diagnosis.
Therefore, if there is a high risk of fetal malformations during pregnancy, you can directly do amniocentesis. With the maturity of amniocentesis technology, the chances of miscarriage or infection of the fetus are already low, don't be too nervous.