title: Normative values of Doppler velocimetry of five major fetal arteries as determined by color power angiography.
abstract: OBJECTIVE
  To produce normograms of Doppler indices of major fetal arteries and their ratios relative to the ascending aorta in a cohort of appropriately grown for gestational age fetuses.
  
  
  METHODS
  Prospective longitudinal study of 70 women with appropriately grown for gestational age fetuses between 24 and 38 weeks' gestation attending the Fetal Growth Clinic of a large UK teaching hospital. Doppler velocimetry of the middle cerebral (MCA), umbilical (UmA) and renal arteries (RA) and the ascending (AAO) and descending (DAO) aortas were studied using color power angiography. Ratios of the Doppler indices [pulsatility index (PI), resistance index (RI), systolic/diastolic (S/D) ratio] were then calculated using the ascending aorta as the reference numerator for the other four vessels to produce normograms. Regression analysis was performed to determined the significance, if any, of the changes in these ratios with gestation.
  
  
  RESULTS
  The normograms of the various Doppler indices were similar for the middle cerebral artery, ascending and descending aortas. There was an initial rise to a peak between 30 and 32 weeks and then a gradual return to values at 38 weeks similar to those at 24 weeks' gestation. In the renal artery, the indices showed very little variation with gestation. However, there was a gradual fall in the indices with gestation in the umbilical artery. The ratios of the various indices relative to that of the ascending aorta demonstrated an increase with gestation. The changes with gestation were statistically significant for the ratios of the indices from the ascending aorta to those of the middle cerebral, renal and umbilical arteries but not for those of the descending aorta.
  
  
  CONCLUSIONS
  The vascular resistance in the five fetal arteries decreased towards the end of pregnancy and the ratios of their indices relative to those of the ascending aorta decreased from 24 to 38 weeks' gestation. Early subtle changes in circulation in compromised fetuses may be identified early from deviations in these normograms.
authors.affiliation: Fetal Growth and Development Research Group, Department of Cancer Studies and Molecular Medicine, Leicester Warwick Medical School, University of Leicester, Leicester, UK. jck4@le.ac.uk
authors.forename: Justin C
authors.initials: JC
authors.lastname: Konje
authors.forename: Keith R
authors.initials: KR
authors.lastname: Abrams
authors.forename: David J
authors.initials: DJ
authors.lastname: Taylor
mesh_terms: D000792:Angiography / Q000379:methods; D001011:Aorta / Q000000981:diagnostic imaging / Q000196:embryology* / Q000502:physiology; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000196:embryology* / Q000502:physiology; D001783:Blood Flow Velocity; D015331:Cohort Studies; D005260:Female; D005333:Fetus / Q000098:blood supply*; D005865:Gestational Age; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000196:embryology* / Q000502:physiology; D011247:Pregnancy; D011446:Prospective Studies; D012044:Regression Analysis; D012077:Renal Artery / Q000000981:diagnostic imaging / Q000196:embryology* / Q000502:physiology; D012212:Rheology; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal / Q000379:methods; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000196:embryology* / Q000502:physiology