title: Modelling the likelihood of levator avulsion in a urogynaecological population.
abstract: BACKGROUND
  Avulsion of the puborectalis muscle is a consequence of vaginal childbirth and associated with female pelvic organ prolapse. It can be palpated, although diagnosis by imaging seems more reliable.
  
  
  OBJECTIVE
  To define the prior probability of avulsion based on history and gynaecological examination, in order to facilitate clinical diagnosis.
  
  
  METHODS
  Over 3 years, 983 women had been assessed by 3D ultrasound at a tertiary urogynaecological unit. We analysed our database for predictors of puborectalis avulsion and designed a simplified predictive model with the help of backwards stepwise logistic regression.
  
  
  RESULTS
  The following factors were strongly associated with the diagnosis of avulsion: age at first vaginal delivery, no stress incontinence, vaginal operative delivery, prolapse symptoms, cystocele, uterine prolapse, minimum Oxford grading of muscle strength and side differences in Oxford grading (all P < 0.001). Multivariate logistic regression produced a model that had an adjusted r(2) of 37.2%, predicting 81% of cases correctly.
  
  
  CONCLUSIONS
  This study was undertaken to define the 'typical' patient suffering from avulsion of the puborectalis muscle, a common childbirth-related injury. Levator defects are most likely in women who had their first child by vaginal operative delivery over the age of 30 years, presenting with symptoms of prolapse without stress incontinence.
authors.affiliation: Nepean Clinical School, University of Sydney, Penrith, Australia. hpdietz@bigpond.com
authors.forename: H P
authors.initials: HP
authors.lastname: Dietz
authors.forename: A
authors.initials: A
authors.lastname: Kirby
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D036861:Delivery, Obstetric / Q000009:adverse effects; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D017773:Pelvic Floor / Q000293:injuries*; D056887:Pelvic Organ Prolapse / Q000000981:diagnostic imaging* / Q000209:etiology*; D011247:Pregnancy; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D014463:Ultrasonography; D055815:Young Adult