What are the prenatal examinations after Down syndrome screening?

Down syndrome screening is a necessary examination item in prenatal check-up, which is mainly used to check whether the fetus has congenital defects and Down syndrome. It is hoped that every mother should make clear the results of Down syndrome screening to reduce the incidence of fetal malformations and congenital diseases. The tests that need to be done after Down syndrome screening are chorionic villus sampling and amniocentesis. It is recommended that pregnant women should follow the doctor's advice to do prenatal check-ups.

Down syndrome screening is the abbreviation for prenatal screening test for Down syndrome. Serum is drawn from expectant mothers to test the concentrations of alpha-fetoprotein, chorionic gonadotropin and free estriol in the maternal serum. The risk factor of giving birth to a fetus with congenital defects is calculated based on the expected date of delivery, weight, age, body weight and gestational age of the pregnant woman at the time of blood collection. Down syndrome screening can only determine the probability of risk. Doctors always leave room for interpretation of screening results: the fetus of a high-risk pregnant woman may not be mentally retarded; the fetus of a non-high-risk pregnant woman may not be non-mentally retarded. The hospital's Down syndrome screening results can only indicate the probability of a baby with Down syndrome, not that high-risk babies definitely have problems. Some expectant mothers have questioned the Down syndrome screening, thinking that the results cannot accurately determine whether the baby is mentally retarded. However, after all, this is the most economical, simple and non-destructive method to determine whether the baby is mentally retarded. If the results are suspicious, further amniocentesis can be performed. Expectant mothers may ask, since the accuracy of Down syndrome screening is not high, why not just do amniocentesis? Because amniocentesis is relatively risky, it is not recommended unless it is absolutely necessary, and the cost is also relatively high.

What does Down syndrome screening test?

Down syndrome screening is mainly for screening Down syndrome, that is, to check whether the baby will be a congenitally stupid Down syndrome baby, mainly checking alpha-fetoprotein, human chorionic gonadotropin, and free estriol.

Fetuses with Down syndrome are not exclusive to older pregnant women. Although older pregnant women over 35 years old are closely related to Down syndrome, the older the age, the greater the chance of giving birth to a child with Down syndrome. However, young women may also give birth to children with Down syndrome, and only 20% of Down syndrome occurs in older pregnant women, while the other 80% of Down syndrome fetuses are born to young pregnant women under 35 years old. Therefore, if only older pregnant women are examined, it will not be a good way to prevent Down syndrome.

On the other hand, if all pregnant women undergo amniocentesis or chorionic villus sampling, not only will the cost be higher, but it will also increase the chance of miscarriage, so it is not necessary for all women to undergo amniocentesis or chorionic villus sampling. Currently, the best way to prevent Down syndrome is that all young pregnant women undergo Down syndrome screening tests, and those who are shown to be at high risk undergo amniocentesis or chorionic villus sampling. Through amniocentesis or chorionic villus sampling, it can be determined whether the fetal chromosomes are normal and whether the fetus has Down syndrome.