title: Role of 'angle of progression' in prediction of delivery mode.
abstract: OBJECTIVE
  The aim of this study was to investigate the role of the 'angle of progression' (AOP) in the prediction of vaginal delivery.
  
  
  METHODS
  In this prospective study, we followed 70 singleton pregnant women. AOP was measured at admission time and also at the beginning of the second stage immediately after digital examination. Digital and ultrasound examiners were unaware of each other's results. The digital examiner decided on the delivery mode based on clinical assessment.
  
  
  RESULTS
  Sixty-five (92.9%) women had vaginal delivery. In the first stage of labor, the area under the curve was 87.5% (95% confidence interval [CI], 77.9-97.1; P = 0.005) for the AOP and 85.5% (95%CI, 75.2-95.6; P = 0.009) for digital examination and in the second stage of labor, the area under the curve was 90.2% (95%CI, 81-99.3; P = 0.003) for the AOP and 94.9% (95%CI, 89.1-100; P = 0.001) for digital examination. An AOP of ≥113° at the second stage was associated with a 90.8% probability of vaginal delivery.
  
  
  CONCLUSIONS
  We found a significant relation between AOP and cervical dilatation during the first stage of labor. A larger angle at the beginning of the second stage was significantly associated with shorter time to delivery.
authors.affiliation: Obstetrics and Gynecology Department, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Vajiheh
authors.initials: V
authors.lastname: Marsoosi
authors.affiliation: Obstetrics and Gynecology Department, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Reihaneh
authors.initials: R
authors.lastname: Pirjani
authors.affiliation: Obstetrics and Gynecology Department, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Baharak
authors.initials: B
authors.lastname: Mansouri
authors.affiliation: Obstetrics and Gynecology Department, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Laleh
authors.initials: L
authors.lastname: Eslamian
authors.affiliation: Obstetrics and Gynecology Department, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ashraf
authors.initials: A
authors.lastname: Jamal
authors.affiliation: School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Heidari
authors.affiliation: Epidemiology and Biostatistics Department, School of Public Health Sciences, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Rahimi-Foroushani
mesh_terms: D000293:Adolescent; D000328:Adult; D036861:Delivery, Obstetric / Q000379:methods*; D005260:Female; D006801:Humans; D007746:Labor Presentation; D010173:Palpation; D011247:Pregnancy; D013997:Time Factors; D014219:Trial of Labor; D016216:Ultrasonography, Prenatal / Q000379:methods*; D055815:Young Adult
keywords: angle of progression; cervical dilatation; delivery mode; transperineal ultrasound; vaginal delivery