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Perianal and perirectal abscess

Elizabeth Breen, MD
Ronald Bleday, MD
Section Editors
Martin Weiser, MD
Lawrence S Friedman, MD
Deputy Editor
Wenliang Chen, MD, PhD


Perianal and perirectal abscesses are common anorectal problems. The infection originates most often from an obstructed anal crypt gland, with the resultant pus collecting in the subcutaneous tissue, intersphincteric plane, or beyond (ischiorectal space or supralevator space) where various types of anorectal abscesses form. Once diagnosed, anorectal abscesses should be promptly drained surgically. An undrained anorectal abscess can continue to expand into adjacent spaces as well as progress to generalized systemic infection.

Anorectal abscesses and fistulas can be thought of as two sequential phases of the same anorectal infectious process: an abscess represents the acute phase of infection, while a fistula represents the chronic phase of suppuration and fistulization [1]. Thus, it is not surprising that 30 to 70 percent of anorectal abscesses are associated with a concomitant anorectal fistula and that 30 to 40 percent of patients develop an anorectal fistula after undergoing treatment for an anorectal abscess [1,2].

The clinical manifestations, diagnosis, and management of anorectal abscess are discussed in this topic. Anorectal fistulas are reviewed in other topics. (See "Anorectal fistula: Clinical manifestations, diagnosis, and management principles" and "Operative management of anorectal fistulas".)


It is estimated that there are approximately 100,000 cases of anorectal infection per year in the United States [1]. The incidence is likely an underestimate as many patients with anorectal symptoms prefer attributing them to "hemorrhoids" to seeking medical attention for an accurate diagnosis.

The mean age of presentation is 40 years (range 20 to 60) [3-6]. Adult males are twice as likely to develop an anorectal abscess and/or fistula compared with females [1,6].

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Literature review current through: Sep 2017. | This topic last updated: Jun 27, 2017.
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