TY - CHAP M1 - Book, Section TI - First 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 PointsNuchal translucency measurement in the first trimester is the most powerful marker for fetal Down syndrome.Combination of nuchal translucency with serum markers in the first trimester detects up to 87% of cases of Down syndrome for a 5% false-positive rate.Septated cystic hygroma, or simple nuchal translucency of 3.0 mm or greater, are indications for chorionic villus sampling (CVS) without need to await serum marker results.First trimester absence of the nasal bones, reversal of flow in the ductus venosus, and tricuspid regurgitation may have a limited role as second-line screening tests for select high-risk patients by expert sonologists.These second-line screening tests are unlikely to have any value for routine general population screening. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/12/11 UR - obgyn.mhmedical.com/content.aspx?aid=1106395715 ER -