title: [Evaluation of blood flow in the fetal renal artery between the 22nd and 38th week in normal pregnancies].
abstract: OBJECTIVE
  to describe values found for the resistance index (RI), pulsatility index (PI) and the systole/diastole (S/D) ratio of fetal renal arteries in non-complicated gestations between the 22nd and the 38th week, and to evaluate whether those values vary along that period.
  
  
  METHODS
  observational study, where 45 fetuses from non-complicated gestations have been evaluated in the 22nd, 26th, 30th and 38th weeks of gestational age. Doppler ultrasonography has been performed by the same observer, using a device with 4 to 7 MHz transducer. For the acquisition of the renal arteries velocity record, a 1 mm to 2 mm probe has been placed in the mean third of the renal artery for the evaluation through pulsed Doppler ultrasonography. The measurement of RI, PI and S/D ratio from three consecutive waves was performed with the automatic mode. To detect significant differences in the indexes' values along gestation, we have compared values obtained at the different gestational ages, through repeated measures ANOVA, followed by Tukey's post-hoc test.
  
  
  RESULTS
  There were no significant differences between the right and left renal arteries, when the RI, IP and S/D ratio were compared. Nevertheless, a change in the values of these parameters has been observed between the 22nd week (RI=0.9 +/- 0.02; PI=2.4 +/- 0.02; S/D ratio=11.6 +/- 2.2; mean +/- standard deviation of the combined mean values of the right and left renal artery) and the 38th week (RI=0.8 +/- 0.03; PI=2.1 +/- 0.2; S/D ratio=8.7 +/- 2.3) of gestation.
  
  
  CONCLUSIONS
  the parameters evaluated (RI, PI and S/D ratio) have presented decreasing values between the 22nd and 38th, with no difference between the fetus's right and left sides.
authors.affiliation: Departamento de Ginecologia e Obstetrícia, Universidade de São Paulo, Ribeirão Preto, SP, Brasil. fmgallarreta@msn.com
authors.forename: Francisco Maximiliano Pancich
authors.initials: FM
authors.lastname: Gallarreta
authors.forename: Wellington de Paula
authors.initials: Wde P
authors.lastname: Martins
authors.forename: Edson Nunes
authors.initials: EN
authors.lastname: de Morais
authors.forename: Adilson da Cunha
authors.initials: Ada C
authors.lastname: Ferreira
authors.forename: Luis Guilherme
authors.initials: LG
authors.lastname: Nicolau
authors.forename: Daniela de Abreu
authors.initials: Dde A
authors.lastname: Barra
authors.forename: Francisco
authors.initials: F
authors.lastname: Mauad Filho
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D009200:Myocardial Contraction; D011247:Pregnancy; D011674:Pulse; D012016:Reference Values; D012039:Regional Blood Flow; D012077:Renal Artery / Q000196:embryology* / Q000502:physiology*; D014655:Vascular Resistance; D055815:Young Adult