Publication:

Overlap repair of isolated internal anal sphincter injury:success and failure

Background Internal anal sphincter (IAS) injury may manifest after other anal surgeries. The pattern of incontinence due to its injury is unique with passage of flatus and/or faecal matter during both day time and sleep. Its repair is extremely challengeable due to its delicate modified smooth muscles. The aim of this study is to evaluate our limited modifications in overlap repair of IAS injury, hoping to reach satisfactory success rates that could encourage the return again to this type of repair.

Methods This is a prospective controlled study on 17 patients with isolated IAS injury that were operated upon by a modified overlap repair. Endoanal ultrasonography and anorectal manommetric studies were done preoperatively for all cases. Wexner continence score was estimated preoperatively and at the end of 2nd, 6th and 12th months postoperatively. Our definition of failure was having postoperative Wexner score of > 8 or a drop to < 50% of the preoperative score (if it was preoperatively <16).

Results Failure rate was greatly affected by the size of defect. Age and preoperative resting anal pressure were not prognostic factors for failure. After 12 months follow-up, we reached 70.6% success rate.

Conclusions IAS repair under certain circumstances (size of defect not more than half of the circumference of IAS, single injury to the sphincter, and with well experienced surgeons) worth the trial of repair with hopeful results.