Prenatal Screening and Diagnosis for Chromosomal Abnormalities and Neural Tube Defects Algorithm

The American Congress of Obstetricians and Gynecologists (ACOG) recommends that diagnostic testing for chromosome abnormalities and open neural tube defects (ONTD) be offered to all pregnant women. In women of low to average risk, traditional serum testing is often used as a first tier screen, with cell-free DNA (cfDNA) screening as a second-tier test, although cfDNA is also acceptable as an initial screening test. For high-risk women, cfDNA or amniocentesis is recommended.