Most anal fistulas originate in anal crypts, which become infected, with ensuing abscess formation. When the abscess is opened or when it ruptures, a fistula is formed. Other causes include opened perianal or ischiorectal abscesses, which drain spontaneously through these fistulous tracts. Fistulas are also found in patients with inflammatory bowel disease, particularly Crohn's disease. The incidence of fissures in Crohn's disease is 30%-50%. Anal fistulas can also be associated with diverticulitis, foreign-body reactions, actinomycosis, chlamydia, lymphogranuloma venereum, syphilis, tuberculosis, radiation exposure, and HIV disease. Anal warts caused by human papillomavirus, hemorrhoids, and solitary rectal ulcer syndrome are all differential diagnoses for anal fistula.
Learn more about anal fistula etiology.
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Cite this: Richard H. Sinert. Fast Five Quiz: Anal Fissures and Fistulas - Medscape - Sep 15, 2022.