title: Anal sphincter trauma and anal incontinence in urogynecological patients.
abstract: OBJECTIVE
  To determine the prevalence of evidence of residual obstetric anal sphincter injury, to evaluate its association with anal incontinence (AI) and to establish minimal diagnostic criteria for significant (residual) external anal sphincter (EAS) trauma.
  
  
  METHODS
  This was a retrospective analysis of ultrasound volume datasets of 501 patients attending a tertiary urogynecological unit. All patients underwent a standardized interview including determination of St Mark's score for those presenting with AI. Tomographic ultrasound imaging (TUI) was used to evaluate the EAS and the internal anal sphincter (IAS).
  
  
  RESULTS
  Among a total of 501 women, significant EAS and IAS defects were found in 88 and 59, respectively, and AI was reported by 69 (14%). Optimal prediction of AI was achieved using a model that included four abnormal slices of the EAS on TUI. IAS defects were found to be less likely to be associated with AI. In a multivariable model controlling for age and IAS trauma, the presence of at least four abnormal slices gave an 18-fold (95% CI, 9-36; P < 0.0001) increase in the likelihood of AI, compared with those with fewer than four abnormal slices. Using receiver-operating characteristics curve statistics, this model yielded an area under the curve of 0.86 (95% CI, 0.80-0.92).
  
  
  CONCLUSIONS
  Both AI and significant EAS trauma are common in patients attending urogynecological units, and are strongly associated with each other. Abnormalities of the IAS seem to be less important in predicting AI. Our data support the practice of using, as a minimal criterion, defects present in four of the six slices on TUI for the diagnosis of significant EAS trauma.
authors.affiliation: Departamento de Ginecología y Obstetricia, Facultad de Medicina, Clínica Alemana - Universidad del Desarrollo, Santiago, Chile.|Departamento de Ginecología y Obstetricia, Hospital Clínico de la Universidad de Chile, Santiago, Chile.
authors.forename: R A
authors.initials: RA
authors.lastname: Guzmán Rojas
authors.affiliation: Department of Obstetrics and Gynecology, Sydney Medical School Nepean, University of Sydney, Penrith, Australia.|Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: I
authors.initials: I
authors.lastname: Kamisan Atan
authors.affiliation: Department of Obstetrics and Gynecology, Sydney Medical School Nepean, University of Sydney, Penrith, Australia.|Department of Obstetrics and Gynecology, Liverpool Hospital, University of Western Sydney, Sydney, NSW, Australia.
authors.forename: K L
authors.initials: KL
authors.lastname: Shek
authors.affiliation: Department of Obstetrics and Gynecology, Sydney Medical School Nepean, University of Sydney, Penrith, Australia.
authors.forename: H P
authors.initials: HP
authors.lastname: Dietz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001003:Anal Canal / Q000000981:diagnostic imaging / Q000293:injuries*; D005242:Fecal Incontinence / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D016015:Logistic Models; D008875:Middle Aged; D015999:Multivariate Analysis; D007744:Obstetric Labor Complications / Q000000981:diagnostic imaging* / Q000453:epidemiology; D011247:Pregnancy; D015995:Prevalence; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D014054:Tomography; D014463:Ultrasonography; D055815:Young Adult
keywords: 3D/4D ultrasound; anal incontinence; anal sphincter; anal sphincter trauma; fecal incontinence; transperineal ultrasound