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- 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
A high pelvirectal abscess may cause minimal symptoms (lower abdominal pain and fever).
Common in 1st year of life
- Predominant age: all ages (most common in 3rd and 4th decades and during infancy)
- Predominant sex: male > female (2 to 3:1)
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
- Staphylococci (especially methicillin-resistant)
- Bacteroides fragilis
- Pseudomonas aeruginosa
- 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
- 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.