title: Why are some women with pelvic floor dysfunction unable to contract their pelvic floor muscles?
abstract: BACKGROUND
  Many women with pelvic floor dysfunction are unable to voluntarily contract their pelvic floor muscles. This study hypothesised that women who cannot contract their pelvic floor muscles, despite specialised pelvic floor physiotherapy, are likely to have avulsion defect of the levator ani muscle, visible on 3-dimensional ultrasound.
  
  
  METHODS
  Pelvic floor muscle strength was assessed by modified Oxford scale in all women presenting to a tertiary urogynaecology clinic with a main complaint of urinary incontinence ± pelvic organ prolapse. Women who could not contract their pelvic floor muscles (PFM) after having training with a specialised pelvic floor physiotherapist, (modified Oxford score of 0 or 1), were invited to participate in 3-dimensional transperineal ultrasound.
  
  
  RESULTS
  Of 625 women presenting with urinary incontinence and/or pelvic organ prolapse, 150 (24.0%) were unable to contract their PFM at initial assessment. After specialised pelvic floor physiotherapy, 20 of 150 (15.3%) could not contract and were termed 'noncontractors'. Of these, 12 agreed to participate in transperineal ultrasound. Levator avulsion defects were detected in 8 of 12 (66.7%).
  
  
  CONCLUSIONS
  Our results show that 67% of women who cannot contract their PFM despite physiotherapy have levator avulsion defects. The mechanism affecting the remaining 33% is yet to be discovered.
authors.affiliation: Pelvic Floor Unit, St George Hospital, Sydney, New South Wales, Australia.
authors.forename: Sia
authors.initials: S
authors.lastname: Kim
authors.forename: Vivien
authors.initials: V
authors.lastname: Wong
authors.forename: Kate H
authors.initials: KH
authors.lastname: Moore
mesh_terms: D000368:Aged; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength; D017773:Pelvic Floor / Q000000981:diagnostic imaging / Q000503:physiopathology*; D059952:Pelvic Floor Disorders / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D056887:Pelvic Organ Prolapse / Q000150:complications; D014463:Ultrasonography; D014549:Urinary Incontinence / Q000150:complications
keywords: levator avulsion; pelvic floor muscle; pelvic floor muscle strength; pelvic floor muscle training; physiotherapy