Is early or mid-term screening more accurate?

With the opening up of the two-child policy, there are now more and more older pregnant women. For these women, after 14 weeks of pregnancy, they will need to do Down syndrome screening. Through Down syndrome screening, we can determine the probability of test tube embryo deformity. If the risk is relatively high, then everyone will also need to do the next puncture examination. If it is confirmed that there is a problem with the embryo development process, the pregnancy should be terminated as soon as possible. Some people also heard that Down syndrome screening can be done in the early stage, so which one is more accurate in the early stage or in the middle and late stage?

Down syndrome screening is actually a screening method. We cannot actually make a final diagnosis in the early and late stages. Generally, we evaluate the success rate based on the diagnosis rate and false positive rate. If the diagnosis rate is relatively high, then it is a good screening method. According to current medical technology, the diagnosis rate of early stage dysentery is higher than that of moderate stage dysentery, and the false positive rate is lower than that of moderate stage dysentery. Early Down syndrome and mid-down syndrome are actually assessments of the risk of Down syndrome. If you are doing Down syndrome screening, then after doing it in the early stage, you don't need to do screening in the middle and late stages. If you adopt the early and mid-pregnancy screening strategy, you need to do mid-pregnancy screening after doing early Down syndrome screening, and then you can calculate the risk.

If our Down syndrome screening data shows that the baby is a key target, it only means that the fetus is more likely to have Down syndrome, but there may also be Down syndrome in the low-risk group. What needs to be made clear is that Down syndrome screening can only help us determine the probability of a baby with Down syndrome, but it cannot confirm whether the fetus has already had Down syndrome. In other words, a high blood test index value can only prove that the chance of having a baby with Down syndrome is higher, but it does not mean that the baby must have a problem. Even if the test result is low risk, we should not ignore it. We still need to see a doctor regularly for routine physical examinations, and through B-ultrasound and other tests

Now we should know whether the early or late stage screening for Down syndrome is more accurate. Relatively speaking, the early stage will be more accurate, but now the medical equipment in many areas is not very advanced, so the most common is the late stage screening. After the screening, if the risk is found to be relatively high, everyone needs to do the next step of testing. A high risk only means that the probability of Down syndrome is higher, but it cannot be determined at this time that the fetus is definitely a Down syndrome child.