Non-invasive techniques include examinations of the woman 's womb through ultrasonography and maternal serum screens (i.e. Alpha - fetoprotein). Blood tests for select trisomies (Down syndrome in the United States, Down and Edwards syndromes in China) based on detecting cell - free placental DNA present in maternal blood, also known as non-invasive prenatal testing (NIPT), have become available. If an elevated risk of chromosomal or genetic abnormality is indicated by a non-invasive screening test, a more invasive technique may be employed to gather more information. In the case of neural tube defects, a detailed ultrasound can non-invasively provide a definitive diagnosis.
which tests are noninvasive and performed to detect chromosomal abnormalities in the fetus
ultrasonography maternal serum screens non-invasive prenatal testing (NIPT)