Non-invasive DNA testing: safe and accurate prenatal screening technology

Non-invasive DNA testing (NIPT) is a prenatal screening technology that collects peripheral blood from pregnant women and analyzes fetal cell-free DNA. It is mainly used to detect chromosomal abnormalities (such as Down syndrome). Its core advantage lies inNon-invasive(Avoid the risk of amniocentesis),High accuracy(The detection rate for trisomy 21 is >99%) andearly operability(Can be tested after 10 weeks of pregnancy). The content will be expanded in order: technical principles, applicable groups, testing procedures, clinical value and precautions.

Technical principles and scientific basis

Non-invasive DNA testing is based onCell-free fetal DNA (cffDNA)Presence in maternal blood (accounting for approximately 5%-10% of maternal blood DNA). Through high-throughput sequencing technology, we can compare the differences in the number of DNA fragments to determine whether there are chromosomal abnormalities. For example, if the number of chromosome 21 segments is significantly increased, it indicates that the fetus may have Down syndrome. This technology is21-Trisomy, 18-Trisomy, 13-TrisomyThe screening accuracy is significantly higher than traditional serological screening.

Applicable groups and testing process

This test is suitable forElderly pregnant women (≥35 years old),Serology Screening High RiskorA history of childbearing with chromosomal abnormalitiesgroup. The process is divided into three steps: 1. Draw 10mL of blood after 10 weeks of pregnancy; 2. Separate the plasma and sequence it in the laboratory; 3. A report will be issued in 7-10 working days. It should be noted that NIPT isscreening methodsRather than a diagnostic tool, high-risk results need to be further verified through amniocentesis.

Clinical value and limitations

Non-invasive DNA testing has significantly reduced the use rate of invasive examinations and reduced the psychological burden on pregnant women. But its limitations include:Unable to detect structural anomalies(such as neural tube defects),Slightly less accurate for multiple pregnancies, and the price is relatively high (2000-3000 yuan). The current domestic mainstream products are as follows:

Summary and Notes

Non-invasive DNA testing is an important advancement in prenatal screening, but the results need to be viewed rationally:Low risk does not rule out other abnormalities,High risk requires diagnosis. It is recommended to conduct comprehensive evaluation combined with ultrasound examination under the guidance of a doctor. At present, this technology has been recommended by the "China Prenatal Screening Guidelines", but it has not yet been included in medical insurance and requires self-pay for testing.

Quote sources:

1. "Chinese Journal of Obstetrics and Gynecology" 2021 "Expert Consensus on the Application of Non-invasive Prenatal Testing Technology"
2. BGI official website NIFTY® product manual
3. National Health Commission's "Prenatal Screening Technology Management Measures" 2020 Edition