title: Automated 3D ultrasound measurement of the angle of progression in labor.
abstract: OBJECTIVE
  To assess the feasibility and reliability of an automated technique for the assessment of the angle of progression (AoP) in labor by using three-dimensional (3D) ultrasound.
  
  
  METHODS
  AoP was assessed by using 3D transperineal ultrasound by two operators in 52 women in active labor to evaluate intra- and interobserver reproducibility. Furthermore, intermethod agreement between automated and manual techniques on 3D images, and between automated technique on 3D vs 2D images were evaluated.
  
  
  RESULTS
  Automated measurements were feasible in all cases. Automated measurements were considered acceptable in 141 (90.4%) out of the 156 on the first assessments and in all 156 after repeating measurements for unacceptable evaluations. The automated technique on 3D images demonstrated good intra- and interobserver reproducibility. The 3D-automated technique showed a very good agreement with the 3D manual technique. Notably, AoP calculated with the 3D automated technique were significantly wider in comparison with those measured manually on 3D images (133 ± 17° vs 118 ± 21°, p = 0.013).
  
  
  CONCLUSIONS
  The assessment of the angle of progression through 3D ultrasound is highly reproducible. However, automated software leads to a systematic overestimation of AoP in comparison with the standard manual technique thus hindering its use in clinical practice in its present form.
authors.affiliation: a Department of Obstetrics and Gynecology , Sant'Orsola Malpighi University Hospital, University of Bologna , Bologna , Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Montaguti
authors.affiliation: a Department of Obstetrics and Gynecology , Sant'Orsola Malpighi University Hospital, University of Bologna , Bologna , Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Rizzo
authors.affiliation: a Department of Obstetrics and Gynecology , Sant'Orsola Malpighi University Hospital, University of Bologna , Bologna , Italy.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Pilu
authors.affiliation: a Department of Obstetrics and Gynecology , Sant'Orsola Malpighi University Hospital, University of Bologna , Bologna , Italy.
authors.forename: Aly
authors.identifier: http://orcid.org/0000-0002-9322-2184
authors.initials: A
authors.lastname: Youssef
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005333:Fetus / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007746:Labor Presentation; D008875:Middle Aged; D011247:Pregnancy; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods*; D055815:Young Adult
keywords: 3D ultrasound; Labor; angle of progression; automated; delivery; intrapartum ultrasound; transperineal ultrasound