How many weeks is the best time to screen for Down syndrome?
Down syndrome screening is a non-invasive screening test performed on pregnant women to determine whether the fetus is at risk for Down syndrome. As for the optimal time for Down syndrome screening, different literatures also have certain differences in their introduction. Next, Down syndrome screening will be introduced from four aspects: gestational age, examination methods, examination significance and related indicators.
1. Gestational age
The best time for Down syndrome screening is between 16 weeks and 20 weeks of pregnancy. During this time period, the probability of fetal Down syndrome is highest, and sufficient time can be given to pregnant women for further examination and confirmation of the diagnosis. In addition, screening for Down syndrome between 16 weeks and 20 weeks of pregnancy can also effectively avoid the inappropriateness of early and late pregnancy testing.
2. Inspection method
There are two main examination methods for Down syndrome screening: serum Down syndrome screening and medical ultrasound Down syndrome screening. Serum Down syndrome screening needs to be carried out between the 16th and 20th weeks of pregnancy. Pregnant women’s blood tests are taken to infer the risk of Down syndrome by examining hCG, AFP, PAPP-A and other indicators in the serum. Medical ultrasound screening for Down syndrome determines whether there are abnormal manifestations of Down syndrome by examining the fetal neck thickness and nasal discharge and nasopharynx. Of course, these two inspection methods can be carried out at the same time, and the inspection results can confirm each other, thereby increasing the detection rate.
3. Check the meaning
Down syndrome screening is to detect whether the fetus is at risk of Down syndrome, and its results will have an important impact on the health of pregnant women and fetuses. Early screening can provide pregnant women with sufficient time for further examination and consultation, thereby avoiding unnecessary risks and worries. For those high-risk pregnant women, more complete further examinations will better protect the life and health of the fetus.
4. Related indicators
The three indicators of hCG, AFP, and PAPP-A in the blood are commonly used indicators in serum Down syndrome screening. Among them, elevated hCG levels, reduced AFP levels, and reduced PAPP-A levels are all associated with an increased risk of Down syndrome. In medical ultrasound screening for Down syndrome, neck thickness is a major indicator of Down syndrome infection. When it is larger than 3mm between 16 weeks and 20 weeks of pregnancy, the fetus may be at risk of Down syndrome.
Summary
In short, it is most appropriate to conduct Down syndrome screening between the 16th and 20th weeks of pregnancy. Serum Down syndrome screening and medical ultrasound Down syndrome screening are both commonly used examination methods. The significance of examination is to detect and avoid risks in advance. During the examination, hCG, AFP, PAPP-A and neck thickness are all important examination indicators. For high-risk pregnant women, further examinations will effectively increase the detection rate of Down syndrome.
