title: Use of umbilical-cerebral Doppler ratios in predicting fetal growth restriction in near-term fetuses.
abstract: OBJECTIVE
  To compare the sensitivity and specificity of different umbilical-cerebral ratios in the prediction and detection of fetal growth restriction in near-term fetuses when the umbilical arterial waveform is within normal.
  
  
  METHODS
  A prospective cross-sectional observational study was carried out recruiting consecutive singleton pregnancies with clinically suspected fetal growth restriction after 34 weeks gestation. The umbilical-cerebral ratios were then calculated from the S/D, RI and PI values and correlated with immediate perinatal outcome.
  
  
  RESULTS
  A total of 187 patients were recruited. Twelve cases had abnormal UA Doppler flow velocity waveform studies. Of the 175 with normal UA Doppler findings, 92 (53.1%) were confirmed to have fetal growth restriction (FGR) with birth weights below the tenth centile for gestation. The detection rate of FGR by ultrasound biometry was 96.7%. The mean umbilical artery S/D, RI and PI values were higher in the fetal growth restriction group, while the middle cerebral artery values were lower as compared to fetuses with no growth restriction. A small but significant difference was seen in the umbilical-cerebral ratios of the different indices between the two groups. Receiver operator characteristic curves showed that there was little difference between the performances of the S/D, RI or PI ratios and all had limited power in predicting fetal growth restriction.
  
  
  CONCLUSIONS
  In the presence of normal umbilical artery Doppler waveforms, umbilical-cerebral ratios have limited power to predict fetal growth restriction.
authors.affiliation: Department of Obstetrics and Gynaecology, United Christian Hospital, Hong Kong, China. towkw@ha.org.hk
authors.forename: William W K
authors.initials: WW
authors.lastname: To
authors.forename: Alice M Y
authors.initials: AM
authors.lastname: Chan
authors.forename: Ka-Ming
authors.initials: KM
authors.lastname: Mok
mesh_terms: D001783:Blood Flow Velocity; D003430:Cross-Sectional Studies; D004453:Echoencephalography; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011263:Pregnancy Trimester, Third; D018566:Pregnancy, High-Risk; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D047929:Term Birth; D014465:Ultrasonics; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000000981:diagnostic imaging