Anal vector volume analysis predicts anal sphincter injury in patients with fecal incontinence

Aims: The aim of this study were 1. to determine the role of anal vector manometry in the assessment of anal sphincter injury, 2. to establish the most suitable method of anal vector volume analysis for identifying significant anal sphincter (EAS) injury in patients with fecal incontinence. Methods: A total of 15 consecutive women with a history of instrumental or traumatic vaginal delivery were recruited. Anal ultrasonography and anal vector manometry were performed. Receiver-operator characteristic curves were used to determine the usefulness of anal manometry and anal vector volume analysis in the identification of significant EAS disruption (full thickness, more than one quadrant involved) detected by ultrasonography. Results: 3 women had significant EAS disruption identified by anal ultrasonography. Anal vector manometry provided complementary functional information. Anal vector symmetry index (VSI), determined by analysis of mean maximum squeeze pressure, yielded 100% sensitivity for significant EAS disruption, with a positive predictive value of 65%. Conclusion: Anal vector manometry correlates with endoanal ultrasonography. Anal vector symmetry correlates well with anal sphincter disruption identified by intracavitary ultrasonography.