Implant of Self-Expandable Artificial Anal Sphincter in Patients With Fecal Incontinence Improves External Anal Sphincter Contractility.

Abstract Background: External anal sphincter contractility significantly contributes to control the passage of stool. An artificial anal sphincter placed into the intersphincteric space is a safe and effective procedure to treat fecal incontinence, even if its mechanism of action has not been fully elucidated. Objective: The aim of this study was to evaluate external anal sphincter contractility changes after a self-expandable hyexpan prostheses was implanted into the intersphincteric space of the anal canal and clinical outcomes compared. Design: This was a prospective clinical study. Settings: The study was conducted at a university teaching hospital. Patients: Consecutive patients affected by fecal incontinence for at least 6 months after failure of conservative treatment were included. Interventions: All of the patients underwent 10-prostheses implantation and were examined preoperatively and postoperatively by endoanal ultrasound and anorectal manometry. Main outcome measures: Fecal incontinence symptoms were assessed by severity scores. The external anal sphincter muscle tension was calculated using a specific equation. Results: Thirty-nine patients (34 women; median age = 68 y) were included in the study; no morbidity was registered. After a median follow-up period of 14 months, both the median maximum voluntary squeeze pressure and the median inner radius of the external anal sphincter significantly increased. A statistically significant increase of external anal sphincter muscle tension was detected. A decrease of any fecal incontinence symptom and an improvement in severity scores were observed at the last follow-up examination. The external anal sphincter contractility was significantly higher in patients reducing incontinence episodes to solid stool by >50% and improving their ability to defer defecation for >15 minutes. Limitations: This was a single-center experience with a relatively small and heterogeneous sample size, patients with a potentially more severe disease because our institution is a referral center, and an absence of quality-of-life evaluation. Conclusions: Artificial anal sphincter implantation improved the external anal sphincter muscle tension; there was a positive correlation between its increase and the clinical outcome.