title: ACOG Committee Opinion #296: first-trimester screening for fetal aneuploidy.
abstract: First-trimester screening for chromosomal abnormalities offers potential advantages over second-trimester screening. Studies in the 1900s demonstrated an association between chromosomal abnormalities and the ultrasonographic finding of abnormally increased nuchal translucency (an echo-free area at the back of the fetal neck) between 10 and 14 weeks of gestation. First-trimester screening using nuchal translucency, free beta-hCG, and pregnancy-associated plasma protein-A has comparable detection rates and positive screening rates for Down syndrome as second-trimester screening using 4 serum markers (alpha-fetoprotein, beta-hCG, unconjugated estriol, and inhibin-A). Although first-trimester screening for Down syndrome and trisomy 18 is an option, it should be offered only if certain criteria can be met.
mesh_terms: D000782:Aneuploidy; D015415:Biomarkers / Q000097:blood; D000013:Congenital Abnormalities / Q000175:diagnosis*; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis; D016216:Ultrasonography, Prenatal
chemical_list: D015415:Biomarkers