What is Down's syndrome screening during pregnancy?

Down syndrome screening is a new item in prenatal check-up. Among the prenatal check-up items, Down syndrome screening is very important. It can check whether the fetus suffers from certain diseases. Down syndrome screening is divided into early pregnancy and mid-pregnancy. What we usually call Down syndrome screening refers to Down syndrome screening conducted in mid-pregnancy. So, what does Down syndrome screening check during pregnancy?

What does Down syndrome screening test during pregnancy?

Down screening is the general name for prenatal selection tests for Down syndrome. It is one of the must-do items in pregnancy checkups. It is a test method that extracts blood cells from pregnant women and tests the levels of some biochemical indicators in the mother's blood cells to select high-risk pregnant women with fetal aneuploidy trisomy 21 and trisomy 18, and calculate the risk of giving birth to a child with Down syndrome.

Is it necessary to do Down syndrome screening? Down syndrome (DS), also known as 21-trisomy syndrome or congenital idiocy, is a genetic disease with autosomal abnormalities, accounting for 95% of chromosomal diseases. Although most babies with Down syndrome often miscarry spontaneously in the early stages of their mother's pregnancy, the fertility rate of Down syndrome babies still accounts for 1/600-1/800 newborns, so Down syndrome screening is very necessary. Pregnant women over 35 years old are at high risk for Down syndrome, and it is recommended that pregnant women aged 35 years or older should undergo Down syndrome screening.

Down syndrome is also known as congenital idiocy or trisomy 21. Among the 23 pairs of sex chromosomes in the human body, chromosome 21 is a relatively short pair, with relatively less genetic material on it. Even if abnormalities are found, it will not cause fatal adverse effects. Therefore, babies born with Down syndrome will not necessarily have any abnormalities, repeated vaginal bleeding, or fetal growth retardation. They will usually be born safely and have a long lifespan.

Types of Down syndrome screening

Early Down syndrome screening

Down syndrome screening in early pregnancy is a combination of nuchal translucency (NT) screening with B-ultrasound examination and blood cell biochemical examination results to conduct a risk assessment on the possibility of a fetus with sex chromosome genetic diseases in expectant mothers. Early Down syndrome screening can detect a very high proportion of Down syndrome and other chromosomal abnormalities, but because the accuracy of the nuchal translucency scanner is determined by many factors, including the level of the ultrasound doctor and the accuracy of the scanner used, early pregnancy Down syndrome screening still has certain defects. If Down syndrome screening fails in the early stage, you can do nothing or do related tests for diagnosis, such as amniocentesis, for a more detailed diagnosis.