title: Utility of intrapartum transperineal ultrasound to predict cases of failure in vacuum extraction attempt and need of cesarean section to complete delivery.
abstract: OBJECTIVE
  We aim to evaluate the predictive capacity of intrapartum transperineal ultrasound (ITU) to predict cases of failure in fetal extraction in operative deliveries with vacuum. Prospective, observational study performed on 61 nulliparous women, ≥ 37 weeks, singleton pregnancies at full dilatation who underwent transperineal ultrasound before placement of vacuum to complete fetal extraction. Working on the transperineal longitudinal plane, we evaluated the following: Angle of Progression (AoP), Progression Distance (PD) and head direction. In the transverse plane, midline angle (MLA) and head-perineum distance were assessed. Vacuum extractions were classified as easy (EG) (three or less vacuum pulls), difficult (DG) (more than three vacuum pulls) or impossible (IG) (delivery completed by cesarean section). Occipito-posterior presentations were not evaluated.
  
  
  RESULTS
  Fifty-two patients were studied (26-EG, 19-DG and 7-IG). No differences in obstetric, intrapartum or neonatal characteristics were observed between study groups, with the following exceptions: weight at birth (3147 g-EG, 3523 g-DG and 3588 g-IG) and number of vacuum pulls (1.4-EG, 4.4-DG and 4.1-IG; p < 0.0005). The AoP pushing was 133.1° ± 13.6-EG, 112.8° ± 12.8-DG and 99.1° ± 8.9-IG (p < 0.0005); "head-up" direction was identified in 84.6% of EG, 36.8% of DG and 28.6% of IG (p < 0.001); PD were 37.0 ± 10.4 mm, 33.3 ± 23.3 mm and 20.8 ± 9.5 mm (p < 0.0005); MLA were 35.0° ± 19.6, 55.3° ± 24.4 and 76.0° ± 23.2 (p = 0.003); and head-perineum distances were 41.8 ± 6.6 mm, 49.2 ± 9.8 mm and 48.0 ± 3.4 mm (p = 0.072), respectively.
  
  
  CONCLUSIONS
  We have observed that the presence of an AoP with pushing <105°, a PD <25 mm, a "head-down" direction and a >45° MLA are very unfavorable ITU parameters which can be used to identify cases of high risk of fetal extraction failure in vacuum-assisted deliveries.
authors.affiliation: a Department of Obstetrics and Gynecology , Valme University Hospital , Seville , Spain .|b Department of Obstetrics and Gynecology , University of Seville , Spain , and.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Sainz
authors.affiliation: a Department of Obstetrics and Gynecology , Valme University Hospital , Seville , Spain .
authors.forename: Carlota
authors.initials: C
authors.lastname: Borrero
authors.affiliation: a Department of Obstetrics and Gynecology , Valme University Hospital , Seville , Spain .
authors.forename: Adriana
authors.initials: A
authors.lastname: Aquise
authors.affiliation: a Department of Obstetrics and Gynecology , Valme University Hospital , Seville , Spain .
authors.forename: Rosa
authors.initials: R
authors.lastname: Serrano
authors.affiliation: a Department of Obstetrics and Gynecology , Valme University Hospital , Seville , Spain .
authors.forename: Laura
authors.initials: L
authors.lastname: Gutiérrez
authors.affiliation: c Biostatistics Unit, Department of Preventive Medicine and Public Health , University of Seville , Seville , Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Fernández-Palacín
mesh_terms: D000328:Adult; D002585:Cesarean Section; D005260:Female; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D007746:Labor Presentation; D010502:Perineum; D011247:Pregnancy; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014620:Vacuum Extraction, Obstetrical / Q000009:adverse effects*
keywords: Intrapartum ultrasound; labor; pushing; transperineal ultrasound; vacuum delivery