[Treatment of anal fistulas]

It is generally accepted that laying-open constitutes the only effective cure for anal fistulae. The sacrifice of at least some part of the anal sphincter apparatus is therefore the inevitable consequence of every operation for fistula. In the case of an intersphincteric or low-trans-sphincteric fistula, only the internal sphincter or the lower half of the external sphincter need to be incised. This may usually be performed without endangering postoperative faecal continence. High trans-sphincteric or suprasphincteric fistulae, however, involve the entire external sphincter and/or the puborectalis muscle. Straightforward trans-section of these sphincters would lead to faecal incontinence. For this reason such high fistulae should be progressively laid open in staged procedures, after encircling the sphincters for some weeks with a seton. The same procedure should also be employed for complex horseshoe-shaped fistulae. Contrary to traditional teaching, anal fistulae in Crohn's disease are no exception to these general therapeutic guidelines. Finally, exploration for an underlying fistula and, if possible, immediate fistulotomy are advocated for all patients with an acute perianal abscess.