title: Transperineal sonographic assessment of angle of progression as a predictor of successful vaginal delivery following induction of labor.
abstract: OBJECTIVE
  To assess whether measurement of the angle of progression (AOP) before induction of labor (IOL) can predict successful vaginal delivery in nulliparous women.
  
  
  METHODS
  This was a prospective, observational study of nulliparous women with a singleton term pregnancy and an indication for IOL. Transperineal sonography was used to measure the AOP before cervical ripening. Since all women enrolled had a low Bishop score, 98.6% of them were induced with either intracervical extra-amniotic balloon catheter or vaginal prostaglandin E-2. The staff in the labor ward were blinded to the AOP measurements. Clinical data were retrieved from computerized medical records.
  
  
  RESULTS
  Of the 150 women included in the final analysis, 40 (26.7%) delivered by Cesarean section. The median AOP was narrower in women who had a Cesarean delivery than in those who delivered vaginally (90° (interquartile range (IQR), 84-94.5°) vs 98° (IQR, 90.8-105°); P < 0.001). When including only women who underwent Cesarean delivery for non-progression of labor (n = 27) in the analysis, an AOP of > 92° (derived from a receiver-operating characteristics curve) was associated with a successful vaginal delivery in 94.8% of women. Multivariate stepwise logistic regression analysis including maternal age, body mass index, gestational age, estimated fetal weight, fetal head station, indication for IOL and AOP demonstrated that only AOP was independently associated with the prediction of a successful induction.
  
  
  CONCLUSIONS
  AOP may be a useful sonographic parameter for predicting successful vaginal delivery among nulliparous women at term undergoing IOL; an AOP wider than 92° is associated with a high rate of vaginal delivery. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.
authors.affiliation: Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, Israel, affiliated to the Hebrew University and Hadassah School of Medicine, Jerusalem, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Gillor
authors.affiliation: Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, Israel, affiliated to the Hebrew University and Hadassah School of Medicine, Jerusalem, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Vaisbuch
authors.affiliation: Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, Israel, affiliated to the Hebrew University and Hadassah School of Medicine, Jerusalem, Israel.
authors.forename: S
authors.initials: S
authors.lastname: Zaks
authors.affiliation: Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, Israel, affiliated to the Hebrew University and Hadassah School of Medicine, Jerusalem, Israel.
authors.forename: O
authors.initials: O
authors.lastname: Barak
authors.affiliation: Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, Israel, affiliated to the Hebrew University and Hadassah School of Medicine, Jerusalem, Israel.
authors.forename: Z
authors.initials: Z
authors.lastname: Hagay
authors.affiliation: Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, Israel, affiliated to the Hebrew University and Hadassah School of Medicine, Jerusalem, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Levy
mesh_terms: D000328:Adult; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D002585:Cesarean Section / Q000706:statistics & numerical data*; D036861:Delivery, Obstetric / Q000379:methods*; D005260:Female; D006801:Humans; D007751:Labor, Induced; D011237:Predictive Value of Tests; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012372:ROC Curve; D014463:Ultrasonography / Q000379:methods*
keywords: AOP; Bishop score; Cesarean delivery; cervical ripening; nulliparous; translabial sonography; ultrasound; vaginal delivery