title: Prevalence of levator ani muscle injury and health-related quality of life in primiparous Chinese women after instrumental delivery.
abstract: OBJECTIVE
  Levator ani muscle (LAM) injury is common after first vaginal delivery, and a higher incidence is associated with instrumental delivery. This study was conducted to compare the incidence of LAM injury after forceps or ventouse extraction in primiparous Chinese women, and to study their subsequent health-related quality of life.
  
  
  METHODS
  This prospective observational study was conducted between 1 September 2011 and 31 May 2012 in a tertiary obstetric unit. All eligible primiparous women who had undergone instrumental delivery were recruited 1 to 3 days following delivery. The subjects completed the Pelvic Floor Distress Inventory questionnaire and Pelvic Floor Impact Questionnaire, and translabial ultrasound was performed 8 weeks' postpartum to determine whether the subjects had suffered LAM injury.
  
  
  RESULTS
  Among the 289 women who completed the study, 247 (85.5%) had ventouse extraction and 42 (14.5%) had forceps delivery. Subsequent translabial ultrasound identified a total of 58 women with LAM injury. The prevalence of LAM injury after ventouse extraction and forceps delivery was 16.6% (95% CI, 12.0-21.2%) (41/247) and 40.5% (95% CI, 25.6-55.4%) (17/42), respectively (P = 0.001). Forceps delivery was identified as a risk factor for LAM injury, with an odds ratio of 3.54. No statistically significant differences were observed between the quality of life in women who underwent ventouse extraction and those with forceps delivery or between the quality of life in women with a unilateral or bilateral LAM injury.
  
  
  CONCLUSIONS
  In our cohort of primiparous Chinese women, 20.1% (58/289) had LAM injury after instrumental delivery, and forceps delivery was identified as the only risk factor.
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR.
authors.forename: M Y
authors.initials: MY
authors.lastname: Chung
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR.
authors.forename: O Y K
authors.initials: OY
authors.lastname: Wan
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR.
authors.forename: R Y K
authors.initials: RY
authors.lastname: Cheung
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR.
authors.forename: T K H
authors.initials: TK
authors.lastname: Chung
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR.
authors.forename: S S C
authors.initials: SS
authors.lastname: Chan
mesh_terms: D000328:Adult; D044466:Asian People; D002681:China; D005113:Extraction, Obstetrical / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006801:Humans; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000293:injuries*; D009772:Obstetrical Forceps / Q000009:adverse effects; D010298:Parity; D017773:Pelvic Floor / Q000000981:diagnostic imaging / Q000293:injuries*; D011247:Pregnancy; D011446:Prospective Studies; D011788:Quality of Life; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014463:Ultrasonography
keywords: forceps delivery; instrumental delivery; levator ani muscle injury; perineal ultrasound; ventouse extraction