Rectum
Perirectal Abscess
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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 Abscess
es
May also spread from
Pelvis
(PID,
Diverticulitis
, Ruptured
Appendicitis
)
Risk Factors
Crohn's Disease
Diabetes Mellitus
Immunodeficiency
Pregnancy
Symptoms
Constant, throbbing perianal pain
Signs
Gene
ral
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
Gene
ral Measures
Stool Softener
s (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 (
Anaerobe
s,
Gram Negative
s)
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
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