Cutting seton for anal fistulas: high risk of minor control defects

Long-term results of cutting seton in the treatment of anal fistulas were studied.

Of the 44 patients with anal fistulas, mainly of the high variety, managed with this method, 35 (25 men) attended a clinical and manometric follow-up examination on average 70 (range, 28-184) months after operation. Fistula distribution was high transsphincteric (25), low transsphincteric (5), extrasphincteric (3), and suprasphincteric (2). The seton was tightened at one-week to two-week intervals to achieve gradual sphincter division.

Time required to achieve complete fistula healing ranged from 37 to 557 (mean, 151) days. Two (6 percent) of the 35 patients re-examined had recurrence of fistula and 22 (63 percent) reported symptoms of minor impairment in anal control, which in four patients had existed already before operation. Anal resting pressures were similar for defective and normal control, but other manometric variables were inferior in incontinence, although total squeeze pressure only showed statistically significant difference from normal continence (P = 0.0345). Incontinence was likely associated with hard and gutter-shaped operation scars in the anal canal, but the difference from normal continence was not statistically significant.

Cutting seton yields fairly good results in regard to cure of fistula, but the risk of anal incontinence, despite its minor degree, seems to be too high to recommend its routine use for all high fistulas. The suprasphincteric fistulas and some extrasphincteric fistulas are difficult to treat otherwise, but especially for high transsphincteric fistulas, other methods of treatment (preferably those in which sphincter division can be avoided and the risk of anal canal deformity and incontinence are minimized) are advocated.