title: Placental and spiral artery volume and gray-scale value assessment via 3-dimensional sonography in the second trimester.
abstract: OBJECTIVE
  Extreme placental size has been associated with abnormal pregnancy outcomes. The purpose of this study was to establish normal values for placental and spiral artery volume and gray-scale value as assessed via 3-dimensional (3D) sonography in the second trimester.
  
  
  METHODS
  The entry criterion was a documented singleton pregnancy at 14-25 weeks' gestation. Patients with normal pregnancy outcome were stratified into 6 subgroups representing 2-week intervals. Automatic 3D sonographic acquisition of the placental and spiral artery volume and gray-scale value, expressed as a percentage, was obtained.
  
  
  RESULTS
  Out of 199 patients with normal pregnancy outcome, the placental volume was between 77.7 and 213.9 cm(3) and the gray-scale value was between 28.6 and 29.2 cm(3) (depending on gestational age). The spiral artery volume adjacent to placenta was between 47.9 and 108.7 cm(3), and the gray-scale value was between 27.5 and 29.5 cm(3). Statistical analysis in each subgroup of patients revealed a significant difference between placental and spiral artery volumes but no difference when the gray-scale value was compared.
  
  
  CONCLUSIONS
  We defined normal placental and spiral artery volume and gray-scale value in the second trimester of normal pregnancy using 3D sonography.
authors.affiliation: Department of Obstetrics, Gynecology, and Women's Health, John A. Burns School of Medicine, University of Hawaii, 1319 Punahou Street, Honolulu, HI 96826, USA.
authors.forename: Ivica
authors.initials: I
authors.lastname: Zalud
authors.forename: Steven
authors.initials: S
authors.lastname: Shaha
mesh_terms: D000328:Adult; D001158:Arteries / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D010920:Placenta / Q000098:blood supply / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods*