Anorectal abscess

Background

Anorectal abscess types and their locations.

• Usually begin via blocked anal gland (leads to infection/abscess formation)
  • Can progress to involve any of the potential spaces.

	Perianal	Ischiorectal	Intersphincteric, deep postanal, pelvirectal
Epidemiology	Most common	Second most common	Least common
Symptoms	Located close to anal verge, posterior midline, superficial tender mass	Larger, indurated, well-circumscribed, located laterally on medial aspect of buttocks	Rectal pain, skin signs may not be present
Comments	High incidence of fistula formation even with drainage		Constitutional symptoms often present

Risk Factors

• Crohn's disease
• Chronic constipation
• Diabetes mellitus
• Chronic corticosteroid use

Clinical Features

Perianal abscess.

Perianal abscess.

• Worsening pain around bowel movement, with decreased pain post rectal evacuation
• Perirectal abscesses often accompanied by fever, leukocytosis
  • May only be palpable via digital rectal exam
  • Perianal abscesses typically do not cause fever in immunocompetent individuals
• Tender inguinal lymphadenopathy may be only clue to deeper abscesses

Differential Diagnosis

Anorectal Disorders

• Anal fissure
• Anal fistula
• Anal malignancy
• Anal tags
• Anorectal abscess
• Colorectal malignancy
• Condyloma acuminata
• Constipation
• Crohn's disease
• Cryptitis
• GC/Chlamydia
• Hemorrhoids
  • Internal hemorrhoid
  • External hemorrhoid
• Pedunculated polyp
• Pilonidal cyst
• Proctitis
• Pruritus ani
• Rectal foreign body
• Rectal prolapse
• Syphilitic fissure

Skin and Soft Tissue Infection

• Cellulitis
  • Hand cellulitis
  • Facial cellulitis
  • Orbital cellulitis
• Erysipelas
• Lymphangitis
• Folliculitis
• Hidradenitis suppurativa
• Skin abscess
  • Anorectal abscess
  • Bartholin gland abscess
  • Pilonidal abscess
  • Scrotal abscess
• Necrotizing soft tissue infections
  • Necrotizing fasciitis
  • Necrotizing myositis
  • Necrotizing cellulitis
  • Fournier's gangrene
• Mycobacterium marinum

Look-A-Likes

• Sporotrichosis
• Osteomyelitis
• Deep venous thrombosis
• Pyomyositis
• Purple glove syndrome
• Tuberculosis (tuberculous inflammation of the skin)

Evaluation

• CT with IV contrast can be useful to define deep abscesses (especially with pain out of proportion to exam)
• May consider ultrasound or MRI as alternatives

Management

• Isolated perianal abscess is only type of anorectal abscess that should be treated in ED
  • Consider either linear incision with packing, elliptical incision, or cruciate incision without packing
  • Frequent sitz baths
• All perirectal abscesses (ischiorectal, intersphincteric, supralevator) should be drained in the OR
• All anorectal abscesses require surgical referral and follow up

Antibiotics

Causative organisms: Mixed infection with fecal flora for anaerobes and Gram Negatives (Bacteroides fragilis and Escherichia coli)

Use is controversial

• Only recommended in high risk patients:
  • Elderly
  • Diabetics
  • Systemic signs (fever, leukocytosis)
  • Valvular heart disease
  • Cellulitis
  • Immunosuppression
• Possibly prevent fistula formation in otherwise healthy patients

Treatment options:

• Augmentin
• Ciprofloxacin 500mg PO BID and Metronidazole 500mg PO TID

Disposition

Discharge

• Perianal abscess

See Also

• Anorectal Disorders

External Links

• Rob Orman Lecture