Anorectal Abscess
Basics
Description
- Localized induration, inflammation, and infection of the cryptoglandular tissues of the anal canal
- 80% are perianal; the remainder are intrasphincteric or supralevator.
- On clinical continuum with anorectal fistula, chronic or recurrent infection predisposes to fistula formation.
- System(s) affected: gastrointestinal, skin/exocrine
- Synonym: perianal abscess; perirectal abscess
Geriatric Considerations
A high pelvirectal abscess may cause minimal symptoms (lower abdominal pain and fever).
Pediatric Considerations
Common in 1st year of life
Epidemiology
- Predominant age: all ages (most common in 3rd and 4th decades and during infancy)
- Predominant sex: male > female (2 to 3:1)
Incidence
Common
Etiology and Pathophysiology
- Bacterial invasion of the anal glands found in the intersphincteric space, which may begin with an abrasion or tear in lining of anal canal, rectum, or perianal skin
- The internal anal sphincter serves as a barrier to infection between gut lumen and perianal tissues.
- Four types: Perianal (perirectal) is the most common (60%). Ischiorectal is the next most common followed by intersphincteric and supralevator (1)[C].
- Organisms (usually mixed aerobic; anaerobic)
- Escherichia coli
- Streptococci
- Staphylococci (especially methicillin-resistant)
- Bacteroides fragilis
- Pseudomonas aeruginosa
Risk Factors
- Inciting trauma
- Injections for internal hemorrhoids
- Enema tip abrasions
- Puncture wounds from eggshells or fish bones
- Foreign objects
- Prolapsed hemorrhoid
- Inflammatory bowel disease
- Chronic granulomatous disease (especially Crohn disease)
- Immunodeficiency disorders
- Hematologic malignancies (5–8% have anorectal abscess at some time)
- Diabetes mellitus
- Chronic medical immunosuppression
- Morbid obesity
General Prevention
- Avoid constipation.
- Avoid rectal thermometers, enemas, or suppositories whenever possible in immunocompromised patients.
Commonly Associated Conditions
- Crohn disease
- Other inflammatory disease (e.g., appendicitis, salpingitis, diverticulitis)
- Consider perianal hidradenitis suppurativa or HIV disease in patients with recurring perianal or ischiorectal abscesses.
- Consider anal fistula in patients with recurrent perianal abscesses in same location.
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Citation
Domino, Frank J., et al., editors. "Anorectal Abscess." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688571/all/Anorectal_Abscess.
Anorectal Abscess. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688571/all/Anorectal_Abscess. Accessed October 11, 2024.
Anorectal Abscess. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688571/all/Anorectal_Abscess
Anorectal Abscess [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 October 11]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688571/all/Anorectal_Abscess.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Anorectal Abscess
ID - 1688571
ED - Domino,Frank J,
ED - Baldor,Robert A,
ED - Golding,Jeremy,
ED - Stephens,Mark B,
BT - 5-Minute Clinical Consult, Updating
UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688571/all/Anorectal_Abscess
PB - Wolters Kluwer
ET - 33
DB - Medicine Central
DP - Unbound Medicine
ER -