Tang sieve and sugar sieve are completely different concepts. Sugar screening is a screening for gestational diabetes , which is aimed at pregnant women. Tang Screen is a screening for Down syndrome , which mainly targets the fetus. Down syndrome is now mainly detected early through screening. After pregnancy, pregnant women should go to the hospital for prenatal examination in time. Regular prenatal examination is a prerequisite for discovering Down syndrome. Yan Ruiling, attending physician of the Department of Obstetrics and Gynecology at the First Affiliated Hospital of Jinan University, suggested in an online interview with a family doctor that pregnant women can undergo joint screening during early pregnancy after they are confirmed to be pregnant before 10 weeks of pregnancy; Down's screening can be performed through early pregnancy ultrasound combined with serology screening at 11 to 14 weeks. Down syndrome screening is mainly done through serology and ultrasound, and generally there is no risk. In addition, Dr. Yan Ruiling also introduced the main testing methods for Down’s screening.
How to do Down's screening during early pregnancy?
Early pregnancy Ultrasound detection indicators mainly include: the thickness of the fetal neck transparent layer, the fetal head and hip length, whether the tricuspid valve has regurgitation, intravenous catheter, fetal heart rate, and serological examination. Serology tests in early pregnancy, including pregnancy-related proteins and embryo CT tests. Combining these projects can calculate an early risk. The accuracy of early screening is relatively high, reaching 95%.
What should I do if I missed the screening for early pregnancy?
Dr. Yan Ruiling said that if the examination time exceeds 14 weeks, serological screening can only be performed during the middle pregnancy. At present, triple experiments are mainly conducted during middle pregnancy, and its accuracy rate will be relatively low, 50% to 70%. If you miss the time for early pregnancy and middle pregnancy examinations, you can only perform non-invasive DNA gene testing. The accuracy of non-invasive DNA testing can reach 99%, but it is relatively expensive.
Can ultrasound large extinction test also screen for Down syndrome?
Degenerative examination is usually performed around 20 weeks of pregnancy. Some expectant mothers may think that the generative sieve has been included in the Tang sieve, but in fact, the generative sieve cannot be completely screened. Dr. Yan Ruiling said that children with Down syndrome have a special face, such as widening eye distance and flat nose bridge. But in fact, the fetus was smaller during the middle pregnancy, so he did not have a very obvious sign under ultrasound. Let’s talk about the abnormality of in chromosome 121, because chromosome 21 is relatively short and it carries less genetic material. Therefore, even if the child is a Down child, he will generally not have very serious deformities and may survive until full term. In other words, under ultrasound, one of the simple manifestations is the absence of the nasal bone or the short femur, and it does not have a fatal deformity. So ultrasound may not necessarily eliminate it. There are also some children who have nothing to do with ultrasound, but they are born as a Down child. So why we have always said that Down’s screening is because of its complexity.
What should we read about the report on Down syndrome screening?
Down syndrome screening, there are three main types of : early pregnancy, middle pregnancy, and non-invasive DNA. The monitored report will eventually give a risk value. The cutoff value used in during early pregnancy is 1:300, which means that it finally gives a correction risk. If its risk is greater than 1:300, we can only call it a high risk. If it is less than 1:300, we will remind him to be a low-risk group. During the middle pregnancy, 1:170 is generally used as a cutoff value. If its risk is greater than 1:170, we will consider it to be a high-risk group. If it is less than 1:170, it is a low-risk group. The examination of non-invasive DNA will eventually give you a low risk and a high risk.
In addition, in addition to high and low risks, Down's screening results also have a critical risk. Just as I said, any pregnant woman has a risk of having a Down family. Therefore, general reports will give a low-risk and high-risk, which divide pregnant women into a high-risk group and a low-risk group. However, in order to increase the detection rate, some hospitals may set another critical risk for those close to high risks. For pregnant women who have high or critical risk examinations, further invasive examinations are required to confirm the diagnosis.
This article guides doctors:
Yan Ruiling, First Affiliated Hospital of Jinan University Obstetrics Attendant Physician
