Impact of two different types of anal retractor on fecal continence after fistula repair: a prospective, randomized, clinical trial.

Purpose: This study was designed to compare two different types of anal retractors (Parks vs. Scott) with regard to their impact on fecal continence after fistula repair.
Methods: Between November 2000 and November 2001, 30 patients were randomized into two groups. In Group A (n = 15), a Parks retractor was used during fistula repair, whereas in Group B (n = 15), the repair was performed with a Scott retractor. Before and three months after surgery, maximum anal resting pressure and maximum anal squeeze pressure were recorded. In addition, continence status was evaluated using both the Rockwood Fecal Incontinence Severity Index and the scoring system according to Parks.
Results: In Group A, the median anal resting pressure dropped from 76 mmHg to 42 mmHg. In Group B, no significant difference was observed between the preoperative and postoperative anal resting pressure. The difference in the changes from baseline between the two groups was statistically significant (P = 0.035). No significant changes in anal squeeze pressure were observed. In Group A, the median Rockwood fecal incontinence score increased from 0 to 12. In Group B, the median Rockwood fecal incontinence score did not change after the operation. The difference between the two groups was statistically significant (P = 0.038).
Conclusions: The use of a Parks retractor during perianal fistula repair has a deteriorating effect on fecal continence, probably because of damage to the internal anal sphincter. Because this side effect was not observed after the use of a Scott retractor, we advocate the use of this retractor during all fistula repairs.