What is noninvasive prenatal genetic testing (NIPT)? What is the difference between prenatal diagnosis and general prenatal diagnosis?

Non-invasive prenatal genetic testing is a new generation of prenatal detection technology that uses a new generation of high-throughput sequencing to detect fetal chromosomal abnormalities.

By collecting pregnant women's peripheral blood, the free DNA fragments (including fetal free DNA) in pregnant women's peripheral blood were sequenced, and the risk of fetal chromosome aneuploidy was calculated by biological information analysis. This technique can detect 2 1- trisomy, 18 trisomy and 13 trisomy at the same time, and can also find other chromosome aneuploidies and chromosome deletion/duplication. The key of this technology is non-invasive, that is, non-invasive to the fetus, which is a concept relative to traditional interventional detection. This technology can reduce unnecessary puncture and relieve the pressure of prenatal diagnosis laboratory; Reduce abortion caused by puncture; Relieve the anxiety of pregnant women; Reduce missed diagnosis and avoid medical disputes; Gestational weeks 12-24 weeks, singleton, twin and IVF pregnant women can be detected. Results Age, race and pregnancy-related diseases such as diabetes were not affected. However, this technology also has its limitations: at present, it is impossible to detect chromosome abnormalities caused by translocation; Robertsonian translocation's syndrome and chimeric Down's syndrome cannot be detected; Unable to detect genetic diseases; Open neural tube defects cannot be screened; It is impossible to predict the complications in the third trimester; If the test is high-risk, follow-up prenatal diagnosis should be considered. At the same time, it should be clear that non-invasive prenatal genetic testing belongs to the category of screening and prenatal diagnosis belongs to the category of diagnosis. Although it has similar accuracy to prenatal diagnosis, it still cannot replace prenatal diagnosis. Prenatal diagnosis is a means to diagnose whether the fetus has some hereditary or congenital diseases before birth, which is of great clinical significance for preventing and controlling the incidence of neonatal diseases. At present, prenatal diagnosis is mainly based on traumatic diagnosis methods, including chorionic puncture in the first trimester, amniotic fluid puncture in the second trimester and umbilical cord puncture in the third trimester. People's Republic of China (PRC) * * and national health industry standard Ws 322. 1-20 10 stipulate that prenatal diagnosis of human nature includes villus sampling, amniocentesis and percutaneous umbilical vein puncture, which are carried out at 10/3 +6 weeks and 16 to 22 weeks respectively. The "gold standard" of prenatal diagnosis is the karyotype analysis of fetal samples obtained through invasive detection. The technology is mature and the accuracy rate is 99%. Disadvantages are that the risk of abortion is 0.5%- 1%, and the risk of fetal teratogenesis is 0.5%- 1%, which may lead to cell culture failure. Therefore, it is mainly used for prenatal diagnosis of high-risk groups (high-risk age and high-risk serological screening). For ordinary people how to choose this question, it is like this. Ordinary people should do a good job in serological screening and NT screening. If the result is high risk, it is suggested to carry out non-invasive prenatal genetic testing first. Why are you doing this? This is because the accuracy of traditional screening is about 60%, which means there are false positives and false negatives. If the results of non-invasive prenatal genetic testing are still high-risk, then puncture is needed for prenatal diagnosis at this time; If the result of non-invasive prenatal genetic test is low risk, there is no need for puncture, which can avoid some false positive pregnant women from doing puncture and reduce the risk of abortion. Of course, for elderly pregnant women and pregnant women with rich economic conditions, it is more reassuring to do a non-invasive prenatal genetic test on the basis of traditional screening.