title: The cerebroplacental Doppler ratio revisited.
abstract: OBJECTIVE
  To evaluate the distribution of Doppler pulsatility index (PI) measurements of the umbilical and middle cerebral arteries in singleton fetuses of women with normal uterine artery blood flow and to construct reference ranges for the cerebroplacental PI Doppler ratio.
  
  
  METHODS
  The PI was determined in the mid-portion of the umbilical artery and the mid- or distal segment of the middle cerebral artery in 306 normal singleton fetuses. The cerebroplacental Doppler ratio (CPR) was determined from paired measurements. After determination of the best fit, reference ranges were constructed for each parameter against gestational age (GA).
  
  
  RESULTS
  The PI for the umbilical artery had a linear relationship with GA (umbilical artery PI = - 0.0246 x GA + 1.7791, r(2) = 0.4025, P < 0.001). The middle cerebral artery PI and the CPR both showed a quadratic relationship with GA (middle cerebral artery PI = - 0.0058 x GA(2) + 0.3335 x GA - 2.7317, r(2) = 0.2365, P < 0.01), (CPR = - 0.0059 x GA(2) + 0.383 x GA - 4.0636, r(2) = 0.2788, P < 0.001).
  
  
  CONCLUSIONS
  The CPR is not constant throughout gestation. Reference ranges constructed by a standardized Doppler technique may be of benefit in the monitoring of high-risk pregnancies.
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Sciences, University of Maryland, Baltimore, MD 21201, USA. aabaschat@hotmail.com
authors.forename: A A
authors.initials: AA
authors.lastname: Baschat
authors.forename: U
authors.initials: U
authors.lastname: Gembruch
mesh_terms: D001783:Blood Flow Velocity; D003430:Cross-Sectional Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging / Q000503:physiopathology; D005865:Gestational Age; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D011247:Pregnancy; D011446:Prospective Studies; D012016:Reference Values; D018617:Ultrasonography, Doppler, Pulsed / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000502:physiology*