title: Differences in the Biometry of the Levator Hiatus at Rest, During Contraction, and During Valsalva Maneuver Between Women With and Without Provoked Vestibulodynia Assessed by Transperineal Ultrasound Imaging.
abstract: BACKGROUND
  Pelvic floor muscle (PFM) involvement is suspected in the pathophysiology of provoked vestibulodynia (PVD); however, the underlying mechanisms are unclear. PFM morphology can be inferred from the biometry of the levator hiatus determined through dynamic ultrasound imaging.
  
  
  OBJECTIVE
  The aim of this study was to determine the nature of PFM involvement in women with PVD via an evaluation of the biometry of the levator hiatus at rest, upon maximal voluntary contraction (MVC) of the PFMs, and upon maximal Valsalva maneuver (MVM).
  
  
  METHODS
  Thirty-eight women with PVD and 39 asymptomatic controls were imaged using 3D transperineal ultrasound. Levator hiatal dimensions (area; left-right [LR] and anteroposterior [AP] diameters) were measured at rest, on MVC, and on MVM. Differences in hiatal dimensions and in relative changes in dimensions from rest to MVC and from rest to MVM were compared between groups using separate 1-way analyses of variance for each measure and task. Analysis of covariance models were used to investigate the impact of levator hiatal dimensions at rest on the relative changes in the levator hiatal dimensions during MVC and MVM.
  
  
  METHODS
  Levator hiatal area, LR, and AP diameters, at rest, on MVC, and on MVM were the main outcome measures. Relative changes in hiatal dimensions were assessed as the percent change in hiatal area, LR diameter, and AP diameter.
  
  
  RESULTS
  In comparison with controls, women with PVD had smaller hiatal areas at rest, on MVC, and on MVM, concurrent with smaller LR diameters on MVM. Women with PVD had a significantly smaller change in hiatal area on MVM than controls, but no differences were evident on MVC. In both groups, smaller levator hiatal dimensions at rest were associated with smaller relative decreases in dimensions on MVC and larger relative increases in dimensions on MVM.
  
  
  CONCLUSIONS
  In comparison to controls, women with PVD appear to have narrower levator hiatus' and less capacity to distend their hiatus on Valsalva. The state of the PFMs at rest appears to significantly influence biometric changes in the PFMs during contraction and Valsalva.
authors.affiliation: School of Rehabilitation Therapy, Queen's University, Kingston, ON, Canada.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Thibault-Gagnon
authors.affiliation: School of Rehabilitation Therapy, Queen's University, Kingston, ON, Canada; School of Rehabilitation Sciences, University of Ottawa, Ottawa, ON, Canada. Electronic address: linda.mclean@uottawa.ca.
authors.forename: Linda
authors.initials: L
authors.lastname: McLean
authors.affiliation: Department of Psychology, Queen's University, Kingston, ON, Canada.
authors.forename: Corrie
authors.initials: C
authors.lastname: Goldfinger
authors.affiliation: Department of Psychology, Queen's University, Kingston, ON, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Pukall
authors.affiliation: Department of Obstetrics and Gynecology, Queen's University, Kingston, ON, Canada.
authors.forename: Susan
authors.initials: S
authors.lastname: Chamberlain
mesh_terms: D000328:Adult; D001699:Biometry; D002170:Canada; D005260:Female; D019220:High-Energy Shock Waves / Q000627:therapeutic use*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D009119:Muscle Contraction; D017773:Pelvic Floor / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D012146:Rest; D014463:Ultrasonography; D014636:Valsalva Maneuver; D056650:Vulvodynia / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*
keywords: Dyspareunia; Pelvic Floor Muscles; Provoked Vestibulodynia; Ultrasound Imaging; Vulvodynia