TY - CHAP M1 - Book, Section TI - Second Trimester Screening for Aneuploidy A1 - Bianchi, Diana W. A1 - Crombleholme, Timothy M. A1 - D'Alton, Mary E. A1 - Malone, Fergal D. PY - 2015 T2 - Fetology: Diagnosis and Management of the Fetal Patient, 2e AB - Key PointsQuad marker serum screening is the most effective form of Down syndrome screening in the second trimester (81% detection rate at a 5% false-positive rate).Presence of a major structural malformation at second trimester sonographic fetal anatomy survey is an indication for genetic amniocentesis.A range of minor markers at second trimester sonographic fetal anatomy survey can be utilized with likelihood ratios to adjust the risk of Down syndrome.Absence of major or minor markers at second trimester sonographic fetal anatomy survey reduces the risk of fetal Down syndrome by 60%.Combinations of screening tests in both first and second trimesters, such as integrated, stepwise, and contingency screening, may be more efficient than screening in either trimester alone. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - obgyn.mhmedical.com/content.aspx?aid=1106395765 ER -