title: Influence of compression of the inferior vena cava in the late second trimester on uterine and umbilical artery blood flow.
abstract: OBJECTIVE
  To evaluate the inferior vena cava compression and its influence on the uterine and umbilical artery blood flow in the late second trimester when the mother is supine.
  
  
  METHODS
  The inferior vena cava diameter was measured by ultrasound B mode scan, and Doppler flow velocimetry of the uterine and umbilical artery was performed in 90 women at 24-27 weeks in the supine and complete left lateral position.
  
  
  RESULTS
  The inferior vena cava diameter in the supine position was significantly smaller than that in the lateral position. The degree of the vena cava compression was associated with an elevation in the uterine artery RI in the supine position. The umbilical artery RI did not couple with either the degree of the compression or the changes in the uterine artery RI.
  
  
  CONCLUSIONS
  The inferior vena cava is compressed in the majority of pregnant women in the second trimester, and the compression may affect the uterine artery blood flow but not the fetal circulation.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Ryo
authors.forename: T
authors.initials: T
authors.lastname: Okai
authors.forename: S
authors.initials: S
authors.lastname: Kozuma
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
authors.forename: A
authors.initials: A
authors.lastname: Kikuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Taketani
mesh_terms: D003251:Constriction, Pathologic / Q000150:complications / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007024:Hypotension, Orthostatic / Q000209:etiology*; D017078:Laser-Doppler Flowmetry; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000209:etiology*; D011262:Pregnancy Trimester, Second; D012039:Regional Blood Flow; D016683:Supine Position; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014469:Umbilical Arteries / Q000502:physiology*; D014599:Uterus / Q000098:blood supply*; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging* / Q000503:physiopathology