Down syndrome screening median multiples

What are the multiples of the median value for alpha-fetoprotein? Many pregnant women go for Down syndrome testing during their prenatal checkups in order to ensure the future health of their children. So, what are the multiples of the median value of alpha-fetoprotein?

What is the multiple of the median value of alpha-fetoprotein?

Alpha-fetoprotein (AFP) is a unique protein present in the blood during the embryonic stage. In adults, the AFP value will only increase during pregnancy or liver disease. During pregnancy, AFP is produced in the yolk sac and fetal liver, enters the amniotic fluid of the pregnant woman through the fetal urine, and then penetrates into the embryo or enters the mother's blood through fetal blood. When the fetus has a neural tube defect, such as anencephaly or spina bifida, the AFP level in the amniotic fluid and the mother's blood will increase. But this is not the only conclusive direct evidence, for example, AFP levels may also rise when you have twin babies. AFP levels below normal generally indicate a risk of Down syndrome. A comprehensive analysis should be made based on the pregnant mother's age, weight and duration of pregnancy. If a high alpha-fetoprotein test shows a problem, other tests are usually needed to get a conclusive result.

As a service test, the high alpha-fetoprotein test can provide a basis for further testing of other items and avoid too many unnecessary tests during the first pregnancy check-up.

The standard value of high alpha-fetoprotein should be more than 2.5MoM. The lower the test value, the higher the chance that the fetus will suffer from Down syndrome. The higher the hCG gonadotropin level, the higher the chance that the fetus will have Down syndrome. In addition, the doctor will enter the alpha-fetoprotein level, hcg gonadotropin level, as well as the pregnant woman's age, weight, and gestational age into the computer, and the computer will calculate the risk of the fetus having Down syndrome. If the test data shows that the risk factor is less than 1/270, it means that the risk factor is relatively low, and the chance of the fetus having Down syndrome is less than 1%. However, if the risk factor is higher than 1/270, it means that the risk factor of fetal illness is high, and further amniocentesis or chorionic villus sampling should be performed.

Why do we need to test for high alpha-fetoprotein in pregnancy test?

Not every pregnant mother needs to do a high alpha-fetoprotein test, but if there are pregnant mothers with the criteria, it is recommended to do a high alpha-fetoprotein test. Because this test is very important for pregnant women, it can screen some important abnormalities in the fetus and then determine whether new projects such as amniocentesis are needed.

1. Confirm open neural tube defect. The application of maternal blood cells in screening neural tube defects Alpha-fetoprotein (AFP) is the most common blood protein in fetal blood cells. It is produced by the yolk sac in early pregnancy and produced in large quantities by the fetal liver in late pregnancy. In the case of open neural tube defects, AFP is leaked from the fetus' body in large quantities, which significantly increases the AFP concentration in the mother's blood cells. Therefore, its role in screening for fetal neural tube defects (NTD) is irreplaceable by other markers at this stage.

The measurement of AFP content in the amniotic fluid of pregnant women can diagnose whether 60%-70% of the fetuses have open neural tube defects. If combined with color Doppler ultrasound examination, the diagnosis of neural tube defects in the fetus can be significantly improved (up to 92.8%). Through prenatal diagnosis, neural tube defects in the fetus can be detected as early as possible, reducing the birth of deformed fetuses. The more common neural tube defects are anencephaly, spina bifida, exencephaly and craniospinal bifida. About 80% of people with neural tube defects develop hydrocephalus.

If the fetus is anencephalic, it can be found that the alpha-fetoprotein (AFP) in the blood cells increases in the second half of pregnancy, and the skull is not visible on B-ultrasound examination. Screening pregnant mothers' AFP in mid-pregnancy can also help confirm whether the fetus has spina bifida.

2. Confirmed Down syndrome. AFP reduction can be seen in Down syndrome, so AFP is often used as a test for Down syndrome.

3. Understand the maturity of the fetus. Because the AFP value in the amniotic fluid and blood cells of pregnant women is related to the gestational age, the age of pregnancy can be inferred and the maturity of the fetus can be understood.

4. Diagnose other diseases. AFP may also rise in cases of fetal death, congenital esophageal atresia, duodenal atresia, omphalocele, congenital nephrotic syndrome, and severe Rh blood type incompatibility with pregnancy.