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Perirectal Abscess
Aka: Perirectal Abscess, Anorectal Abscess
- See Also
- Fistula-in-ano
- Epidemiology
- More common in men
- Pathophysiology
- Infection of the 6-12 anal glands and crypts that surround the anus
- Occurs at mucocutaneous junction (Dentate Line)
- Contiguous spread of infection in to ischiorectal space
- Causative organisms: Mixed infection with fecal flora
- Bacteroides fragilis (most common in adults)
- Escherichia coli (most common in children)
- Types
- Perianal Abscess (60%)
- Local Perianal Abscess
- Immediately adjacent to anal verge
- Intersphincteric Abscess
- Proximal infection spread through the internal and external anal sphincter
- Ischiorectal Abscess (25%)
- Inferior to levator ani
- Two to 3 cm from anal verge
- Pelvirectal Abscess (Supralevator Abscess)
- Abscess superior to levator ani
- Complicated, deep abscess spread from perianal, intersphincter and Ischiorectal Abscesses
- May also spread from Pelvis (PID, Diverticulitis, Ruptured Appendicitis)
- Risk Factors
- Crohn's Disease
- Diabetes Mellitus
- Immunodeficiency
- Pregnancy
- Symptoms
- Constant, throbbing perianal pain
- Signs: General
- Palpable, tender mass in perianal area or in Rectum
- Drainage may be seen via perianal skin tract
- See Fistula-in-ano
- Imaging
- CT Pelvis
- Indicated for evaluation of deep space or complicated abscess
- Intersphincteric Abscess
- Ischiorectal Abscess
- Pelvirectal Abscess (Supralevator Abscess)
- MRI Pelvis
- Indicated for complicated Anal Fistula evaluation
- Management
- Surgical drainage is critical
- See types above for specific approach
- General Measures
- Stool Softeners (e.g. Colace)
- Sitz baths
- Frequent dressing changes
- Antibiotics usually not indicated
- Special Indications
- Systemic signs of infection
- Accompanying Cellulitis
- Valvular heart disease
- Diabetes Mellitus
- Immunocompromised patient
- Antibiotic coverage (Anaerobes, Gram Negatives)
- See Diverticulitis for nuanced antibiotic coverage (Perianal Abscess is treated the same)
- Example Regimen: Ciprofloxacin 500 mg PO bid and Metronidazole 500 mg PO tid
- Complications
- Fistula-in-ano (complicates up to 50% of Perirectal Abscess)
- References
- Goroll (2000) Primary Care Medicine, Lippincott, p. 426
- Jhun and Cologne in Herbert (2015) EM:Rap 15(9): 17-8
- Marx (2002) Rosen's Emergency Medicine, p. 1951
- Roberts (1998) Procedures, Saunders, p. 649-51
- Surrell in Pfenninger (1994) Procedures, Mosby, p. 969