title: One-stop clinic for assessment of risk of chromosomal defects at 12 weeks of gestation.
abstract: Prenatal diagnosis of trisomy 21 requires an invasive test in women considered to be at high risk after screening. At present, there are four screening tests. For a 5% false-positive rate, the sensitivities are approximately 30% for maternal age alone, 60-70% for maternal age and second-trimester maternal serum biochemical testing, 75% for maternal age and first-trimester fetal nuchal translucency (NT) scanning, and 90% for maternal age with fetal NT and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11-14 weeks. This article examines the methodology of first-trimester screening and summarizes the results from all studies reporting on the implementation of this method.
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, King's College London, UK.
authors.forename: K H
authors.initials: KH
authors.lastname: Nicolaides
authors.forename: R
authors.initials: R
authors.lastname: Bindra
authors.forename: V
authors.initials: V
authors.lastname: Heath
authors.forename: S
authors.initials: S
authors.lastname: Cicero
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D005865:Gestational Age; D006801:Humans; D008423:Maternal Age; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018566:Pregnancy, High-Risk; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism; D011296:Prenatal Diagnosis / Q000379:methods / Q000592:standards; D012680:Sensitivity and Specificity; D014463:Ultrasonography
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A