title: A critical appraisal of the use of umbilical artery Doppler ultrasound in high-risk pregnancies: use of meta-analyses in evidence-based obstetrics.
abstract: OBJECTIVE
  To reanalyze randomized controlled trials on the use of umbilical artery Doppler velocimetry in high-risk pregnancies and determine which high-risk pregnancies benefit from the use of Doppler velocimetry.
  
  
  METHODS
  Searching Medline, the Cochrane Library and Embase we found 13 randomized controlled trials on the use of Doppler velocimetry in high-risk pregnancies. Of these, six included pregnancies with strictly defined suspected intrauterine growth restriction and/or hypertensive disease of pregnancy ('well-defined studies'); the rest included a great variety of high-risk pregnancies ('general risk studies'). The studies were analyzed with particular regard to the heterogeneity and to outcome. Audits of the perinatal deaths reported in the randomized controlled trials were performed by a panel of 32 international experts.
  
  
  RESULTS
  The 'well-defined studies' had a more uniform study design as compared to the 'general risk studies' and they showed a significant reduction in antenatal admissions (odds ratio, 0.56; 95% confidence interval, 0.43-0.72), inductions of labor (0.78; 0.63-0.96), elective deliveries (inductions of labor and elective Cesarean sections) (0.73; 0.61-0.88) and Cesarean sections (0.78; 0.65-0.94). By perinatal audit it was found that more perinatal deaths in the 'well-defined studies' were potentially avoidable by use of Doppler velocimetry ( P < 0.0005) and the rate of avoidable perinatal deaths was higher among controls (50%) than cases (20%) in this group.
  
  
  CONCLUSIONS
  The randomized controlled trials on umbilical artery Doppler velocimetry show major differences regarding study design and technical and clinical issues and, therefore, they should not be pooled in a simple meta-analysis. By stratification it was found that only in pregnancies with suspected intrauterine growth restriction and/or hypertensive disease of pregnancy will the use of umbilical artery Doppler velocimetry reduce the number of perinatal deaths and unnecessary obstetric interventions.
authors: Copenhagen University Hospital, Department of Obstetrics and Gynecology, Denmark. hbw@dadlnet.dk
authors: H B
authors: HB
authors: Westergaard
authors: J
authors: J
authors: Langhoff-Roos
authors: G
authors: G
authors: Lingman
authors: K
authors: K
authors: Marsál
authors: S
authors: S
authors: Kreiner
mesh_terms: D016001:Confidence Intervals; D003718:Denmark; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D009774:Obstetrics / Q000379:methods; D016017:Odds Ratio; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D011295:Prenatal Care / Q000706:statistics & numerical data; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler / Q000706:statistics & numerical data*; D016216:Ultrasonography, Prenatal / Q000706:statistics & numerical data*; D014469:Umbilical Arteries / Q000000981:diagnostic imaging*