What is the difference between non-invasive and Down syndrome screening?

Non-invasive and Down syndrome screening are two terms that we often hear, but many people don’t know what they are specifically. This is mainly a pregnancy check for pregnant women. The non-invasive that people often talk about is actually called non-invasive DNA prenatal testing technology. Its main purpose is to detect whether the fetus has a chromosomal disease. As for Down syndrome screening, it is a detailed test for children with Down syndrome. So what is the difference between these two testing technologies?

What is the difference between non-invasive and Down syndrome screening?

After pregnancy, there is an important test during the prenatal check-up - Down syndrome screening, which is a screening for the risk of the fetus developing Down syndrome. Related to Down syndrome screening include non-invasive DNA and amniocentesis. All three are used to screen for fetal chromosomal abnormalities. What are the differences between them? Many expectant mothers can’t tell the difference, so let’s learn about it together below.

1. Inspection Fees

Currently, Down syndrome screening is free in many areas. Pregnant women can undergo free sugar screening after completing the maternal health handbook. But some places charge a fee, and the price is around two to three hundred yuan. The costs of non-invasive DNA and amniocentesis are relatively high, approximately around 2,000 yuan.

2. Inspection Method

Both Down syndrome screening and non-invasive DNA testing are performed by drawing blood from pregnant women and will not cause harm to the fetus. Amniocentesis is a procedure in which a thin needle is passed through the pregnant woman's abdomen, uterine wall, and into the amniotic cavity to extract amniotic fluid for the purpose of diagnosing fetal Down syndrome or chromosomal abnormalities.

3. Accuracy

The accuracy rate of Down syndrome screening is about 70%, the accuracy rate of non-invasive DNA is over 90%, and the accuracy rate of amniocentesis is 100%. In other words, the diagnostic results of amniocentesis are the most accurate and can confirm whether there is a problem with the fetus. The results of Down syndrome screening and non-invasive DNA testing only indicate the level of risk and cannot provide a complete diagnosis, and the accuracy of non-invasive DNA testing is higher.

4. Impact on the Fetus

Down syndrome screening and non-invasive DNA testing are performed through blood drawing and will not cause harm to the fetus. Amniocentesis may cause miscarriage, with a miscarriage rate of about 1%. Because the fetus or placenta may be harmed during the process of extracting amniotic fluid. If amniocentesis is needed, it is best to choose a large hospital.

Down syndrome screening, non-invasive DNA, and amniocentesis, how should pregnant mothers choose?

Currently, most pregnant mothers undergo Down syndrome screening. If the Down syndrome screening indicates high risk or critical risk, the doctor will recommend further testing through non-invasive DNA or amniocentesis. Many pregnant mothers complain that the accuracy of Down syndrome screening is too low. The high risk shown by Down syndrome screening makes them nervous, but then a non-invasive DNA test shows low risk. Pregnant mothers who have the conditions can directly choose non-invasive DNA, which has more accurate results and is more reassuring.

If the pregnant woman is over 35 years old or has abnormal NT in the early pregnancy, they are all in the high-risk group and it is best to directly undergo non-invasive DNA or amniocentesis.