How much blood is needed for Down syndrome screening?

Some physical examinations of female friends during pregnancy are usually carried out through blood tests. This puts a lot of mental and physical pressure on women who are afraid of blood. It also increases the pressure on pregnant women with weaker bodies. So how much blood is needed for Down syndrome screening?

How much blood is needed for Down syndrome screening

Down syndrome screening only requires one tube. It is a test method that extracts blood cells from pregnant women, tests the concentration of alpha-fetoprotein and human gonadotropin in the mother's blood cells, and calculates the risk of having a child with Down syndrome based on the mother's due date, age, weight and weeks of pregnancy when blood was drawn. The best time for screening is the 15th to 20th week of pregnancy.

Generally speaking, Down syndrome screening often uses collaborative serology to screen for Down syndrome. The whole process is to extract the peripheral blood of the pregnant woman and then obtain the blood cells therein. During this whole process, the pregnant woman does not need to fast. During the blood cell test, the concentration of alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) in the mother's blood cells will be tested, and the "risk factor" will be calculated based on the mother's date of birth, age, gestational age at the time of blood test, and weight. In this way, 60-70% of congenital idiocy can be detected. To achieve the goal of being a "saint".

In addition, this test can also detect pregnant women at high risk of neural tube defects, trisomy 18 syndrome and trisomy 13 syndrome. However, if the blood cell test is positive, an amniotic fluid test is also required to confirm the diagnosis. It should be noted that you do not need to be on an empty stomach for the Down syndrome test, but it is also not suitable to be tested after eating too much. If you need to do other tests that require fasting on the same day, you can make preparations according to the basics.

Why do we need Down syndrome screening?

Down syndrome patients have severe intellectual disabilities, congenital idiocy, tongue-throwing dementia, are completely unable to take care of themselves in daily life, and are accompanied by complex cardiovascular diseases. They cannot be cured throughout their lives. The incidence rate is about 1/600 to 1/800. Taking my country as an example, a child with Down syndrome is born every 20 minutes, which brings heavy emotional and financial burdens to the family. According to large-scale screening in capitalist countries in the past 5-6 years, the results show that the fertility rate of Down syndrome patients has an increasing trend.

First of all, there are unavoidable genetic factors. At present, with the increasing air pollution in cities, air pollution in daily life, infection by viruses, chemicals, radioactive radiation sources, home decoration, contraceptives, aging conditions, bad habits such as smoking and drinking will all lead to the increase of Down syndrome. Down syndrome is a sex chromosome defect disease, with an extra chromosome on the 21st sex chromosome, so it is also called trisomy 21 syndrome. The specific manifestations are relatively serious intellectual disabilities, strange appearance, low ears, wide eyes, thick skin on the neck, and body deformity.

Down screening refers to a special testing method that is aimed at special groups that do not have any corresponding disease signs (such as all pregnant women). Through testing, key subjects who are most likely to suffer from a certain disease are selected for subsequent diagnosis-related examinations. One thing that needs to be established is that the purpose of screening is not to diagnose a certain disease, but to select people who are very likely to have a certain disease.