title: The optimal gestational age to examine fetal anatomy and measure nuchal translucency in the first trimester.
abstract: The objective of this study was to determine the optimal gestational age for examining fetal anatomy and nuchal translucency in the first trimester. In a prospective cross-sectional study, 1288 women from an unselected population underwent a detailed assessment of fetal anatomy at 10-14 weeks of gestation (confirmed by crown-rump length) with the use of transabdominal sonography and transvaginal sonography, when necessary. Visualization of fetal anatomy improved with increasing gestational age: 6, 75, 96, and 98% of cases could be visualized at 10, 11, 12 and 13 weeks of gestation, respectively, and was similarly high (98%) at 14 weeks. The ability to measure nuchal translucency was similar from weeks 10 to 13 (100, 98, 98 and 98% success rate), but fell to 90% at 14 weeks. The need for transvaginal sonography steadily decreased with increasing gestational age, being 100, 42, 21, 15 and 11% at 10, 11, 12, 13 and 14 weeks, respectively. From these data it appears that the optimal gestational age to examine fetal anatomy and measure nuchal translucency in the first trimester is 13 weeks.
authors.affiliation: University Department of Obstetrics and Gynaecology, Royal Free Hospital, London, UK.
authors.forename: B J
authors.initials: BJ
authors.lastname: Whitlow
authors.forename: D L
authors.initials: DL
authors.lastname: Economides
mesh_terms: D003430:Cross-Sectional Studies; D018568:Crown-Rump Length; D005314:Embryonic and Fetal Development; D005260:Female; D005333:Fetus / Q000196:embryology*; D005865:Gestational Age; D006801:Humans; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal