Anal sphincter trauma and anal incontinence in urogynecological patients

Objectives 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