The cutting seton: an experience at King Faisal Specialist Hospital

A 30-percent gas incontinence rate has been reported after the use of the cutting seton in complex anal fistulas. This study was undertaken to determine the morbidity and efficacy of the cutting seton in the management of complex anal fistulas at the King Faisal Specialist Hospital.

All patients who had a cutting seton inserted in the colorectal unit at King Faisal Specialist Hospital between 1990 and 1998 were identified from a colorectal data base. The charts of these patients were examined and form the basis of this report. Setons were inserted and tied under general anesthesia after the fistula tract had been identified. All fistulas were transsphincteric, and if it seemed that more than 30 percent of the internal sphincter would need to be divided to "lay open" the tract, a seton was used. Fistulas were designated "high" if the internal opening was above the level of the anal crypts. Setons were tightened under general anesthesia at intervals of three to four weeks until cutting was complete. Patients were followed up until wounds had healed and fistula symptoms had resolved.

Data from 47 patients were analyzed. The mean duration of disease before surgery was 39.1 months. Twenty-five patients had had previous anorectal abscess drainage. The mean number of previous fistula operations was 2.2. Before seton insertion five patients were incontinent to gas, two to liquid stool, and none to solid stool. Continence status before seton surgery was unknown in 11 patients. There were 16 "high" fistulas. Methylene blue dye was used to identify the internal opening in 14 patients when simple probing failed. Setons were tightened on three or more occasions in 12 patients, twice in 19 patients, and once in 16 patients. Mean perineal wound healing time was six months. The mean length of follow-up was 1.1 years, and during this time one fistula recurred. After treatment a total of 17 patients (36.2 percent) were incontinent to gas, 4 to liquid feces (8.5 percent), and 1 to solid feces (2.3 percent). Four patients complained of soiling. Of previously continent patients, 9.5 percent were significantly incontinent to gas, but in addition 21.4 percent were "occasionally" incontinent for gas.

The use of the cutting seton resulted in a significant gas incontinence rate of 9.5 percent after a mean follow-up of 1.1 years. Only 1 fistula recurred.