Down screening critical risk to do non-invasive testing pass rate is not high, the two are not necessarily related, if there is a fetal chromosomal abnormality, non-invasive is also abnormal.
Down screening if lower than 1:380, higher than 1:1000, the test value for the critical risk, that is, intermediate risk value. Some hospitals also use 1:300 and 1:270 as the standard.
Non-invasive DNA testing is a prenatal screening procedure in which peripheral blood is drawn from a pregnant woman and fetal free DNA is examined. It can check for three common aneuploidy abnormalities of fetal chromosomes, also known as trisomy 21, trisomy 18 and trisomy 13.
If the fetus does have a problem, both tests will indicate an abnormality, and if the fetus is fine, the noninvasive will indicate a low risk; it is not the case that if the Down screening is a critical risk, the noninvasive DNA will necessarily have a high pass rate.
If the non-invasive DNA is low risk, observation and regular checkups will be sufficient, while the non-invasive DNA is high risk, further amniocentesis should be performed to confirm the diagnosis.