title: [First trimester diagnosis of chromosomal defects].
abstract: Fetal nuchal translucency thickness at the 11(+0) - 13(+6) weeks scan has been combined with maternal age to provide an effective method of screening for trisomy 21; for an invasive testing rate of 5%, about 75% of trisomic pregnancies can be identified. When maternal serum free B-human chorionic gonadotropin and pregnancy-associated plasma protein-A at 11(+0) - 13(+6) weeks are also taken into account, the detection rate of chromosomal defects is about 85-90%. In 60-70% of fetuses with trisomy 21 the nasal bone is not visible at the 11(+0) - 13(+6) weeks scan and examination of the nasal bone can increase the detection rate of screening by the first trimester scan and serum biochemistry to more than 95%.
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital Medical School, London, UK.
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
authors.forename: Piotr
authors.initials: P
authors.lastname: Wegrzyn
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D005865:Gestational Age; D006801:Humans; D009295:Nasal Bone / Q000002:abnormalities / Q000000981:diagnostic imaging*; D009333:Neck / Q000002:abnormalities / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018566:Pregnancy, High-Risk; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D016216:Ultrasonography, Prenatal
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A