Screening involves isolating a group of pregnant women who have an increased risk of carrying a fetus with a chromosomal abnormality.
Screening tests do not offer a definitive answer, but show us whether there is an increased risk, how great it is, and can have both false positive and false negative results.
Determining the risk group of pregnant women or assessing the risk level is based on detecting the most significant anomalies: Down syndrome (the most common disorder), Edwards syndrome, Patau syndrome and Turner syndrome.
These tests can be both non-invasive and invasive.