title: The use of fetal Doppler cerebroplacental blood flow and amniotic fluid volume measurement in the surveillance of postdated pregnancies.
abstract: BACKGROUND
  This prospective observational study aims at determining the distribution of fetal cerebro-placental Doppler indices and amniotic fluid volume in a homogenous group of uncomplicated postdated pregnancies at 41 weeks. The correlation with incidence of passage of thick meconium-stained liquor in labor was analyzed to decide which parameter would be useful in the surveillance of postdated pregnancies.
  
  
  METHODS
  The amniotic fluid volume, middle cerebral artery pulsatility index, umbilical artery pulsatility index, and cerebroplacental ratio were measured and distribution determined in 118 well-dated singleton pregnancies admitted for routine induction of labor at 41 weeks. The 10th centile and the 90th centile in each Doppler parameter and amniotic fluid volume were chosen to divide each parameter into three centile groups. The prevalence of thick meconium-stained liquor in labor in different Doppler and amniotic fluid volume centile groups was compared using Chi-square test for trend with P < 0.05 taken as statistically significant.
  
  
  RESULTS
  The prevalence of thick meconium-stained liquor in labor was significantly inversely correlated with the middle cerebral artery pulsatility index (P = 0.008), with significant difference across different middle cerebral artery pulsatility index centile groups (P = 0.02). There was no significant difference in the prevalence of thick meconium-stained liquor in labor or oligohydramnios across different umbilical artery pulsatility index centile groups. Neither was there significant difference in the prevalence of thick meconium-stained liquor in labor and oligohydramnios across different cerebroplacental ratio and amniotic fluid volume centile groups. Logistic regression using the 10th centile of middle cerebral artery pulsatility index confirmed that it was a significant independent predicting factor for risk of thick meconium-stained liquor in labor with adjusted odds ratio (95th CI) of 6.14 (1.6-24.1).
  
  
  CONCLUSIONS
  Middle cerebral artery pulsatility index is better than amniotic fluid volume or umbilical artery pulsatility index in predicting the risk of thick meconium-stained liquor in labor in uncomplicated postdated pregnancy at 41 weeks.
authors.affiliation: Department of Obstetrics and Gynecology, University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, China. lamswh@yahoo.com.hk
authors.forename: H
authors.initials: H
authors.lastname: Lam
authors.forename: W C
authors.initials: WC
authors.lastname: Leung
authors.forename: C P
authors.initials: CP
authors.lastname: Lee
authors.forename: T T
authors.initials: TT
authors.lastname: Lao
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D002536:Cerebral Arteries / Q000000981:diagnostic imaging*; D005260:Female; D005333:Fetus / Q000098:blood supply*; D006801:Humans; D007743:Labor, Obstetric; D016015:Logistic Models; D008470:Meconium; D016104:Oligohydramnios / Q000503:physiopathology; D021041:Placental Circulation / Q000502:physiology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011273:Pregnancy, Prolonged; D011446:Prospective Studies; D011673:Pulsatile Flow / Q000502:physiology; D012680:Sensitivity and Specificity; D018615:Ultrasonography, Doppler, Color; D014469:Umbilical Arteries / Q000000981:diagnostic imaging