[Gastrointestinal surgery and gastroenterology. XIII. Classification and diagnosis of perianal fistulas].

Intersphincteric abscesses due to inflammation of an anal gland are the origin of most perianal fistulas. Perianal fistulas are classified into four types. Intersphincteric and transsphincteric fistulas are the most common. The appropriate surgical treatment of perianal fistulas is dependent upon their correct classification. Despite new imaging-techniques, physical examination of the perianal region remains of paramount importance for the preoperative classification of perianal fistulas. At present, endoanal ultrasound with the injection of hydrogen peroxide into the fistulous tract, is advocated as the most suitable method for the preoperative imaging of perianal fistulas.