"Obstetrics and Gynecology" pregnant mothers know one by one without invasive DNA detection


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With the rapid development of various testing methods and medical technology, many new technologies have been applied clinically to benefit more pregnant mothers.But how to choose so many dazzling new technologies?What value is it?Today, Zou Liying, deputy director and chief physician of Beijing Obstetrics and Gynecology Hospital, came to tell you about non -invasive DNA detection technology.

What is non -invasive DNA detection

Non -invasive DNA testing is actually the "nickname" detected by non -invasive fetal chromosome before chromosomes. The English abbreviation NIPT is a screening of common chromosomal non -rectifier abnormalities for the fetus of the fetus from the fetal blood from the peripheral blood of pregnant women.One method ("screen" here).

The advantages of non -invasive DNA detection

① Non -invasive, you can detect the project to detect the mother blood.

② The detection rate of 21-triple, 18-trice body, and 13-trio syndrome of clinical recommendation screening is higher than that of Tang’s screening, which can reach more than 95%, and the false positive rate is less than 1%;Part of the micro -missing and micro -repeat screening belongs to "advanced screening."

The disadvantage of non -invasive DNA detection

① For other chromosomal abnormal screening accuracy other than 21-trice body, 18-trice body and 13-trisomy syndrome is limited.

② The price is relatively expensive.

Speaking of which, is there some pregnant mothers confused again?Since the fetus is free of DNA, no matter where it is found, check it to understand it, the fetal chromosome is not understood.

That’s right, the earliest experts who caught these DNAs also thought so. With an extremely excited mood, I thoroughly interrogated (analysis and testing), and found that the "enemy marshal" who thought it was the "striker" was only the "striker".The very small amount of the fetus in the blood that we originally thought from the DNA was actually from the placenta DNA.Because the placenta is a bridge between the pregnant mother and the baby, the situation of the DNA it carries may be inconsistent with the embryo, or the slight lack of gene fragments in the pregnant mother itself may eventually affect the test results., Thus reporting military conditions, false negatives (non -invasive DNA testing low risk and fetal chromosomal abnormalities) or false positive (non -invasive DNA detection high risk and fetal chromosomes are normal).

Therefore, the clinical application of non -invasive DNA can only be used as a high -level screening, not a diagnosis.Moreover, the use of non -invasive DNA detection needs to consider whether it is suitable and unsuitable.

A suitable crowd of non -invasive DNA detection

① Donald screening or imaging test shows that pregnant mothers who are critical risks are recommended to detect non -invasive DNA tests to increase the detection rate of chromosomal abnormalities (critical risk: no high risk requires the degree of amniotic fluid puncture, but the risk value is a bit highThere are still some unwillingness, that is, the risk value value of the 21-trio of three-body screening 1/1000-1/270,18- = The risk value of the body syndrome 1/1000 ~ 1/350).

② Expressive prenatal diagnosis (such as amniotic fluid puncture) indicators, but at the same time, there are taboos for operations such as amniotic fluid puncture (such as signs of abortion, fever, bleeding, infection, etc.).

③ When the mother consults, the gestational week is more than 20+6 weeks, and the time to misunderstand the screening time, but the pregnant mother still hopes to reduce the risk of 21-triple, 18-trilateral, and 13-trisomy syndrome.

Non -invasive DNA detection inappropriate crowd

① Pregnant mothers who have a history of fetal abnormal fetal abnormal fetal fetal disease.

② The couple or one of them have clear chromosomal abnormalities.

③ A pregnant mothers who have undergone foreign body blood transfusion, transplant surgery, cell therapy or underwriting for immunotherapy.

④ Imaging examination suspects that the fetus has a micro -lack, a micro -repeat syndrome, or a pregnant mother with abnormal possibilities of chromosomes.

⑤ High -risk groups of various genetic diseases.

⑥ Pregnant mothers with malignant tumors.

The doctor believes that there are other situations that significantly affect the accuracy of the results.

Careful use of non -invasive DNA detection

Pregnant mothers with the following situations will have a certain degree of decline in the accuracy of non -invasive DNA detection, or prenatal diagnosis shall be performed in accordance with relevant regulations. It is a cautious crowd who is a cautious DNA detection.

① High risks of pre -delivery screening during early and middle pregnancy.

② Maternal age ≥ 35 years.

③ Severe obesity (weight index> 40).

④ Wise through the in vitro fertilization-embryo transplantation method.

⑤ There is a history of dyeing abnormal fetal child delivery, but except for couples dyeing color abnormalities.

⑥ Pharmaceutical and multi -pregnancy pregnancy.

Non -invasive DNA detection time

Non-invasive DNA testing is generally carried out at 12-26 weeks of pregnancy, and the best testing time is 12-22 weeks of pregnancy.

The results of non -invasive DNA detection judgments

Because non -invasive DNA testing can only be used as a screening method for fetal chromosomes abnormalities, there are only two results: high risk and low risk.

Result 1: When the result is low risk, it does not mean that there is absolutely no problem with the fetal chromosome, and there may still be a small possibility of sieve, that is, there are still small fetal chromosomes abnormalities, and it also needs to combine the later B -ultrasound examination.The means to further exclude fetal abnormalities.If the fetal B ultrasound is found to be an ultrasonic indicator related to the abnormal possible fetal chromosomes, whether the result of non -invasive DNA testing is high risk or low risk, further genetic consultation and corresponding prenatal diagnosis should be performed.

Results 2: When the result is high risk, it should be recommended that pregnant mothers perform corresponding interventional prenatal diagnosis (such as amniotic fluid puncture, umbilical vein puncture, etc.).

Note: High risks are just screening results, which does not mean that the fetus must have chromosomal abnormalities.Therefore, the pregnancy cannot be stopped according to the results of non -invasive DNA detection of high risks. You need to follow the doctor’s advice!

Popularization expert: Zou Liying

Deputy Chief Physician, Deputy Director of the 1st Department of Products and Gynecology Hospital

Democratic time: special outpatient clinics on Wednesday afternoon and Friday morning, and the well -known expert clinic on Thursday morning (based on the source of the day)

Source: "Chinese Reproductive Health"

Beijing Obstetrics and Gynecology Hospital

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