Fistula-in-Ano is an abnormal hollow tract or cavity that is lined with granulation tissue and connects a primary opening inside the anal canal to a secondary opening in the perianal skin; secondary tracts may be multiple and can extend from the same primary opening.
Most fistulas are thought to arise as a result of cryptoglandular infection with resultant perirectal abscess. The abscess represents the acute inflammatory event, whereas the fistula is representative of the chronic process. Symptoms generally affect quality of life significantly, and they range from minor discomfort and drainage with resultant hygienic problems to sepsis.
No definitive medical therapy is available for fistulas, though long-term antibiotic prophylaxis and infliximab may have a role in recurrent fistulas in patients with Crohn disease. Surgery is the treatment of choice, with the goals of draining infection, eradicating the fistulous tract, and avoiding persistent or recurrent disease while preserving anal sphincter function.