title: Normal reference ranges of inferior vena cava doppler indices from 14 to 40 weeks of gestation.
abstract: OBJECTIVE
  To establish normal reference ranges of inferior vena cava (IVC) Doppler velocities in normal singleton pregnancies from 14 to 40 weeks.
  
  
  METHODS
  A prospective descriptive study was conducted on normal singleton pregnancies with confirmed gestational age. The sonographic measurements of IVC Doppler indices, including preload index, peak velocity index for vein, and pulsatility index for vein, were determined by experienced sonographers.
  
  
  RESULTS
  A total of 645 measurements were performed, ranging from 12 to 30 measurements available for each gestational week. The relationship between gestational age and IVC Doppler indices was not linear. The best-fitted regression equations for the indices are as follows: [Formula: see text] [Formula: see text] [Formula: see text] (GA = gestational age in week) All IVC Doppler indices rapidly declined from 14 to 20 weeks of gestation and then they were relatively constant or slightly decreased throughout the rest of pregnancy. The tables of normal reference ranges were constructed.
  
  
  CONCLUSIONS
  Normal reference ranges of IVC Doppler indices for each gestational week from 14 to 40 weeks were constructed. This normative data may be a useful noninvasive tool in evaluation of fetal cardiac function.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine Chiang Mai University, Thailand.
authors.forename: Suchaya
authors.initials: S
authors.lastname: Luewan
authors.forename: Kasemsri
authors.initials: K
authors.lastname: Srisupundit
authors.forename: Fuanglada
authors.initials: F
authors.lastname: Tongprasert
authors.forename: Theera
authors.initials: T
authors.lastname: Tongsong
mesh_terms: D001783:Blood Flow Velocity; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011673:Pulsatile Flow; D012016:Reference Values; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging* / Q000502:physiology