Anal fistula surgery. Factors associated with recurrence and incontinence.

PURPOSE: This study was undertaken to assess results of surgery for fistula-in-ano and identify risk factors for fistula recurrence and impaired continence.

METHODS: We reviewed the records of 624 patients who underwent surgery for fistula-in-ano between 1988 and 1992. Follow-up was by mailed questionnaire, with 375 patients (60 percent) responding. Mean follow-up was 29 months. Fistulas were intersphincteric in 180 patients, transsphincteric in 108, suprasphincteric in 6, extrasphincteric in 6, and unclassified in 75. Procedures included fistulotomy and marsupialization (n = 300), seton placement (n = 63), endorectal advancement flap (n = 3), and other (n = 9). Factors associated with recurrence and incontinence were analyzed by univariate and multivariate regression analysis.

RESULTS: The fistula recurred in 31 patients (8 percent), and 45 percent complained of some degree of postoperative incontinence. Factors associated with recurrence included complex type of fistula, horseshoe extension, lack of identification or lateral location of the internal fistulous opening, previous fistula surgery, and the surgeon performing the procedure. Incontinence was associated with female sex, high anal fistula, type of surgery, and previous fistula surgery.

CONCLUSIONS: Surgical treatment of fistula-in-ano is associated with a significant risk of recurrence and a high risk of impaired continence. Degree of risk varies with identifiable factors.