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Perianal abscess: Clinical manifestations, diagnosis, treatment

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


A perianal abscess, a simple anorectal abscess, is the acute phase manifestation of a collection of purulent material that arises from glandular crypts in the anus or rectum. In comparison, a perianal fistula represents the chronic phase of suppuration in this perirectal process [1]. Perianal abscesses traverse distally in the intersphincteric groove into the perianal skin, where they present as a tender, fluctuant mass (picture 1). A perianal abscess, if undrained, can expand into adjacent tissues (eg, ischiorectal space, supralevator space) as well as progress to a generalized systemic infection.

The anatomy of the anal canal and ischiorectal fossa, clinical manifestations, and treatment of an anorectal fistula are reviewed separately. (See "Operative management of anorectal fistulas" and "Anorectal fistula: Clinical manifestations, diagnosis, and management principles".)


Benign perianal diseases, including fissures, abscesses, fistulas, and hemorrhoids, are common. The prevalence of specific disorders is difficult to estimate since almost any anorectal discomfort is often attributed to symptomatic hemorrhoids.

The prevalence of anal abscesses in the general population is probably much higher than seen in clinical practice since the majority of patients with symptoms referable to the anorectum do not seek medical attention. It is estimated that there are approximately 100,000 cases per year in the United States [1]. The mean age for presentation of anal abscess and fistula disease is 40 years (range 20 to 60) [2-5]. Adult males are twice as likely to develop an abscess and/or fistula compared with women [1,5].


An anal abscess usually originates from an infected anal crypt gland [6]. There are typically 8 to 10 anal crypt glands, arranged circumferentially within the anal canal at the level of the dentate line. The glands penetrate the internal sphincter and end in the intersphincteric plane. An anal abscess develops when an anal crypt gland becomes obstructed with inspissated debris, which permits bacterial growth and abscess formation. The suppuration follows the path of least resistance and the infected fluid collects in the space where the gland terminates. An anal fistula is a connection between two epithelial structures and connects the anal abscess from the infected anal crypt glands to the skin of the buttocks. There is no model to predict when an abscess will develop a fistula [7].


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Literature review current through: Feb 2017. | This topic last updated: Thu Feb 09 00:00:00 GMT+00:00 2017.
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