Complex Perianal Fistulas

Recurrent fistulas, fistulas with multiple external openings, those involving more than one third of the anal sphincter complex, and fistulas involving adjacent organs are considered complex. Fistulas occurring in the setting of perianal Crohn disease or following pelvic radiation are also considered complex. Evaluation of a fistula includes a detailed history and physical examination. Imaging with ultrasonography helps delineate the course of a fistula relative to adjacent structures as well as identify occult branching of the fistula tract. The initial step in treating fistulas is resolving associated inflammation. When treating fistulas with multiple branching tracts, the portion of the tracts outside the anal sphincter complex should be unroofed, with the goal of transforming the complex fistula into a simpler fistula with a single internal opening. The selection of the most appropriate treatment for a complex fistula depends on the etiology, anatomy, patient comorbidities, and condition of surrounding tissue. Key Words: anal fistula, anovaginal fistula, Crohn disease, fistulotomy, rectourethral fistula