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Prenatal examination is sometimes like a double-edged sword. While it guarantees the birth of a healthy life, it also makes many pregnant mothers and expectant fathers worry. If something goes wrong, you have to consider whether to terminate the pregnancy. The most worrying thing is the Down test. Currently, the examinations that can screen Down syndrome include Down screen, non-invasive DNA and amniotic fluid puncture. How should you choose these three types of examinations?
Pros and cons of three types of examinations
3 types of examinations have their pros and cons. Expected mothers must choose carefully according to their needs and conditions.
1, Down screening
Advantages: simple, economical, trauma-free, suitable for a wide range of people.
Disadvantages: The lowest accuracy, about 60-70%, and the sensitivity is low. It is not applicable to high-risk pregnant women or pregnant women with certain hereditary diseases, and it is not applicable to age 35 or above.
2, non-invasive DNA
Advantages: high accuracy (about 90%), high sensitivity, low false positive rate of , no invasiveness, just draw blood.
Disadvantages: high price, some detection cannot be done (currently, only trisomy 21, 18, and 13 can only be used, and twins and chimeric chromosomal abnormalities cannot be detected).
Note that these types of pregnant mothers are not suitable for non-invasive:
people at high risk for examinations in the early and middle pregnancy;
people with pre-term delivery age of 35 years or above;
people with severe obesity (body mass index > 40);
people with in vitro fertilization;
have had a history of abnormal chromosomal delivery;
twins or multiples;
have any situations that doctors believe will affect the accuracy of the results and do not recommend it.
3, amniotic fluid puncture
Advantages: the highest accuracy, can detect 46 chromosomes at a time, and can also detect other chromosomal abnormal diseases. It can be called the gold standard for chromosomal diseases.
Disadvantages: There is trauma and there are certain risks (such as puncture of placenta, intrauterine infections, and low-probability miscarriage).
Therefore, for most pregnant mothers, it is generally not recommended to perform amniotic fluid puncture directly as soon as they come.
How should mothers choose?
1. Economical mothers: Tang Screen → Non-invasive DNA → Amniotic fluid puncture
Before pregnancy, she is healthy and has no family genetic diseases. Pregnant mothers who are not high-risk pregnant women and non-old pregnant women can do Tang Screen directly, and then make the next consideration based on the Tang Screen results.
If the Tang Screening test is low or medium-risk pregnant mother, it is recommended to do non-invasive again.
2. Luxury mother: non-invasive DNA → amniotic fluid puncture
For families who are more worried about this issue, they can directly do non-invasiveness. In fact, 99% of fetal chromosomal abnormalities detected by non-invasive DNA are similar to amniotic fluid puncture. If non-invasiveness does not show Down's risk, you can actually avoid amniotic fluid puncture to avoid economic and mental stress again, but the key is still your choice.
If the non-invasive test is positive, another amniotic fluid puncture is needed, because non-invasive test is a screening method, while amniotic fluid puncture is a diagnostic method.
3. Accurate mother: high-risk factors → Amniotic fluid puncture
This combination has the highest detection rate and can detect abnormal numbers of all chromosomes. It is especially suitable for expectant mothers who have abnormal fertility history, family history and other high-risk factors.
Although various medical methods have made considerable efforts to ensure that the baby is healthy and comes to this world, please remember that as the name suggests, the examination of natural defects is not absolutely correct. Therefore, what pregnant mothers should do is to understand each test method in advance, and understand why they should be done and what they can reveal after doing it.
