What diseases does Down syndrome screening mainly detect?

Down screening is the general name for prenatal selection tests for Down syndrome and is a testing method with special significance. The purpose is to test the blood of pregnant women, test the concentrations of alpha-fetoprotein, human gonadotropin and free estriol in the blood cells of pregnant women, and combine the age, weight, and weeks of pregnancy of the pregnant women to determine the risk of congenital idiocy and neural tube defects in the fetus.

Down syndrome, also known as trisomy 21, is a disease caused by chromosomal abnormalities (an extra sex chromosome 21). 60% of patients will miscarry in the womb, and survivors have significant intellectual disability, unusual appearance, developmental disorders and multiple malformations.

Down syndrome screening

Down's syndrome, also known as trisomy 21, is the most common chromosomal disease in children and is an autosomal abnormality. The main characteristics of patients are delayed language development and intellectual disability, accompanied by growth disorders or malformations of multiple organs. The prevalence of Down syndrome in my country is 1/600~1/800, with an average of one baby born every 20 minutes[3].

Down syndrome screening program

Down syndrome screening during early pregnancy

Early pregnancy generally lasts from 7 to 13 weeks after conception. At this time, dual screening refers to a collaborative screening program that uses blood cell pregnancy-related protein-A and human chorionic gonadotropin or dispersed β-hCG as indicators, combined with parameters such as the age of the pregnant woman to calculate the risk of the fetus suffering from DS.

Down syndrome screening during pregnancy

The second trimester is 14 to 20 weeks after pregnancy. The dual screening at this time refers to a collaborative screening program that uses blood alpha-fetoprotein (AFP) and human chorionic gonadotropin or dispersed β-hCG as indicators, combined with parameters such as the age of the pregnant woman, to calculate the risk of the fetus suffering from DS.

Triple screening can also be carried out during pregnancy. Triple screening refers to a collaborative screening program that uses blood cell AFP plus hCG (or separated β-hCG) plus unconjugated estriol as indicators: combined with parameters such as the age of the pregnant woman to calculate the risk of the fetus suffering from DS.

Down syndrome screening method selection

Dual screening during early pregnancy, dual or triple screening during mid-pregnancy are simple methods and can obtain relatively satisfactory screening results. They are effective in reducing the birth of DS and controlling the incidence of birth defects. According to the actual national conditions of mainland China, at present, dual screening during mid-pregnancy is a reasonable prenatal diagnosis plan for DS.