title: Residual defects of the external anal sphincter following primary repair: an observational study using transperineal ultrasound.
abstract: OBJECTIVE
  Obstetric anal sphincter tears are common and an important factor in the etiology of anal incontinence. The objective of the study was to evaluate the prevalence of residual defects of the external anal sphincter (EAS) after primary repair of obstetric anal sphincter injury using four-dimensional (4D) transperineal ultrasound and to correlate sonographic findings of residual defects and levator avulsion with significant symptoms of anal incontinence, defined as St Mark's fecal incontinence score (SMIS) of ≥ 5.
  
  
  METHODS
  This was a retrospective observational study. One-hundred and forty women were seen after primary repair of obstetric anal sphincter tears in a dedicated perineal clinic at a tertiary hospital in Australia. They all underwent a standardized interview, and physical and 4D transperineal ultrasound examination.
  
  
  RESULTS
  Mean follow-up interval was 1.9 months after delivery. Eighty-nine (64%) women had a 3a/3b tear, 28 (20%) a 3c/4(th) degree tear and 23 (16%) an unclassified 3(rd) degree tear. Thirty-five (25%) patients reported symptoms of anal incontinence. Nine had an SMIS of ≥ 5. A residual defect was found in 56 (40%) cases and levator avulsion in 27 (19%). On multivariate logistic regression, residual defects (P = 0.03; odds ratio (OR) = 6.38; 95% CI, 1.23-33.0) and levator avulsion (P = 0.047; OR = 4.38; 95% CI, 1.02-18.77) were found to be independent risk factors for anal incontinence.
  
  
  CONCLUSIONS
  Residual defects of the EAS were found on transperineal ultrasound in 40% of women after primary repair of obstetric anal sphincter injuries. Although most were asymptomatic, residual anal sphincter defects and levator avulsion were associated with significant symptoms of anal incontinence as quantified using the SMIS.
authors.affiliation: Nepean Clinical School, University of Sydney, Penrith, Australia.
authors.forename: K L
authors.initials: KL
authors.lastname: Shek
authors.forename: R
authors.initials: R
authors.lastname: Guzman-Rojas
authors.forename: H P
authors.initials: HP
authors.lastname: Dietz
mesh_terms: D000293:Adolescent; D000328:Adult; D001003:Anal Canal / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D005242:Fecal Incontinence / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D015994:Incidence; D022125:Lacerations / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000601:surgery*; D016015:Logistic Models; D007744:Obstetric Labor Complications / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000601:surgery*; D016017:Odds Ratio; D010502:Perineum / Q000000981:diagnostic imaging; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014463:Ultrasonography; D014945:Wound Healing; D055815:Young Adult
keywords: anal sphincter; childbirth; incontinence; levator avulsion; transperineal ultrasound