Follow-up studies of sphincter-preserving operations for anal fistulas

This study was designed to evaluate and to compare the outcome of anal fistula surgery using techniques involving minimal sphincter damage (sphincter-preserving) and conventional laying open techniques.

From January 1987 to December 1993, 2,242 patients with anal fistulas were treated surgically, of whom 1,070 had sphincter-preserving operations. These included 530 patients with low intersphincteric fistulas (II L), 116 patients with high intersphincteric fistulas (II H), 73 patients with combined high and low intersphincteric fistulas, 239 patients with transphincteric fistulas (III), and 112 patients with supralevator fistulas (IV). The open method of fistula surgery was used in 1,172 patients.

Of 1,070 sphincter-preserving operations, delayed healing occurred in 49 patients (4.6 percent) and recurrent fistula occurred in 32 patients (3 percent). By using the open method in 1,172 patients, delayed healing occurred in 10 patients (0.9 percent) and recurrence of fistula occurred in 23 patients (2 percent). Failure rates increased with increasing depth and complexity of the fistula.

Sphincter function is better with sphincter-preserving fistula surgery than with the open method, although healing was delayed more commonly in sphincter-preserving operations that with the open methods, and fistula recurrence was similar with the two methods. Choice of operation depends on depth of fistula, outcome by manometry, and history of former operations.