What is Down syndrome screening and what does it specifically check for?

Down syndrome screening is a test method that is very likely to detect whether a mother is pregnant with a child with Down syndrome, and the accuracy rate is very high. Therefore, every time this test is done, many mothers will feel a lot of pressure. On the one hand, they are worried that the high risk may just be an illusion, and on the other hand, there may really be a problem. What kind of Down syndrome screening is real? When doing Down syndrome screening, how do you need to check?

Analysis: What is Down syndrome screening?

Down syndrome screening test is the abbreviation of prenatal screening test for Down syndrome. Down syndrome is also called trisomy 21 syndrome, congenital idiocy. It means that the patient's 21st pair of chromosomes has one more than the normal person (normal people have one pair). It is the most common chromosomal aneuploidy disease.

Down syndrome screening is a detection method that extracts serum from pregnant women, tests the concentrations of alpha-fetoprotein, chorionic gonadotropin and free estriol in the maternal serum, and calculates the risk of giving birth to a fetus with congenital defects based on the pregnant woman's due date, weight, age and gestational age at the time of blood collection. If the results of the Down screening test show that the fetus is at a higher risk of Down syndrome, further confirmatory tests should be carried out - amniocentesis or chorionic villus sampling.

The critical value is 1/250-380 (this value may vary due to different methodologies). Greater than is high risk, less than is low risk. The probability of having Down syndrome (DS) in the general population (under 35 years old) is 1/750. According to the examination time, it is divided into early pregnancy (9-13 weeks) and mid-pregnancy (14-21 weeks).

Discussion: Is Down syndrome screening necessary?

Opponents: If you cannot accept amniocentesis, do not do Down syndrome screening to avoid adding psychological burden

A low risk result detected by Down syndrome screening does not necessarily mean that the child will be healthy. If a high risk is detected, amniocentesis will be required for further confirmation. However, amniocentesis has the risk of causing miscarriage. If the baby is healthy but miscarries due to amniocentesis, it will be very painful.

Supporters: Down syndrome screening must be done to be responsible for the child and the family

The risk of amniocentesis is not as high as rumored. After the test results come out, if the diagnosis can be finally confirmed, the expectant mother's heart will be at ease and she will not be suspicious and uneasy throughout the pregnancy. If you don't do Down syndrome screening and end up giving birth to a child with Down syndrome, both the child and the adult will suffer.

Experts say

Down syndrome screening is based on inferring the fetal condition based on maternal blood indicators. The biochemical indicators in the maternal blood will be affected by many factors, and the age of the pregnant woman is also an interfering factor. The older the age, the higher the risk. These factors make it impossible for the results of Down syndrome screening to be very accurate. Of course, it does not mean that pregnant women with medium risk or low risk will not give birth to a child with Down syndrome. To determine whether the baby is Down syndrome, high-risk pregnant women need to undergo amniocentesis. Amniocentesis is not as scary as imagined. Researchers around the world are working on a non-invasive alternative to amniocentesis that would allow expectant mothers to get accurate results without having to worry about the effects on the fetus.