title: Detection of structural abnormalities in the first trimester using ultrasound.
abstract: During the past 25 years, embryonic and early fetal ultrasound and diagnosis have increasingly gained attention in pregnancy care. Modern high-frequency ultrasound transducers make it possible to obtain detailed images of the early conceptus and its organs, and thus move part of the anatomy and anomaly scan from the second to the first trimester. Today, detection of embryonic and fetal structural abnormalities in the first trimester has frequently been reported. One has to distinguish between diagnosis during the early period until about 10 weeks when the embryo or early fetus is small and transvaginal ultrasound is applied, and diagnosis during the late period at the nuchal translucency screening, usually carried out using transabdominal ultrasound. Early first-trimester abnormalities are often diagnosed by chance on clinical indications, whereas late first-trimester diagnoses are the result of systematic screening using ultrasound markers.
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, National Center for Fetal Medicine, Norway; Department of Obstetrics and Gynecology, University Hospital Trondheim, Norway. Electronic address: harm-gerd.blaas@ntnu.no.
authors.forename: Harm-Gerd Karl
authors.initials: HG
authors.lastname: Blaas
mesh_terms: D000013:Congenital Abnormalities / Q000000981:diagnostic imaging* / Q000196:embryology; D042241:Early Diagnosis; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D016216:Ultrasonography, Prenatal
keywords: embryo; first trimester; foetus; sonoembryology; structural abnormalities