Anorectal abscess

The cause of most anorectal abscesses is an infection of one of the anal glands that drain into the anal canal at the level of the dentate line. The anatomical location of the abscess depends on the spread from the anal gland—perianal abscesses are most common. Pain may be the only indication of a deeper anorectal abscess, and signs of inflammation may not be visible.

Urgent surgical drainage is the primary treatment for an anorectal abscess. Antibiotic therapy is usually only an adjunct to surgery. Infection is often polymicrobial, involving aerobic and anaerobic bowel flora. Treat mild infection as for uncomplicated (nonsevere) diverticulitis; treat severe infection as for complicated (severe) diverticulitis.