II. Epidemiology

  1. More common in men (twice risk of women)
  2. Anorectal Abscess Incidence: >100,000 cases per year in U.S.
  3. Age: 20 to 60 years old (mean 40 years old)

III. Pathophysiology

  1. Infection of the 6-12 anal glands and crypts that surround the anus circumferentially
    1. Occurs at mucocutaneous junction (Dentate Line)
    2. Intestinal columnar epithelium lies proximal to the Dentate Line
    3. Squamous epithelium is present distal to the Dentate Line
  2. Contiguous spread of infection in to ischiorectal space
    1. Infection spreads through the internal anal sphincter, and into the intersphincteric plane
  3. Causative organisms: Mixed infection with fecal flora
    1. Bacteroides fragilis (most common in adults)
    2. Escherichia coli (most common in children)

IV. Risk Factors

  1. Crohn's Disease
  2. Diabetes Mellitus
  3. Immunodeficiency
  4. Pregnancy
  5. Chronic Corticosteroid ues
  6. Anorectal Trauma
  7. Radiation fibrosis
  8. Perirectal tumor

V. Types: Anorectal Abscess

  1. Superficial: Perianal Abscess (60%)
    1. Local Perianal Abscess
    2. Immediately adjacent to anal verge
  2. Deep: Perirectal Abscess
    1. Intersphincteric Abscess
      1. Proximal infection spread through the internal and external anal sphincter
    2. Ischiorectal Abscess (25%)
      1. Inferior to levator ani
      2. Two to 3 cm from anal verge
    3. Pelvirectal Abscess (Supralevator Abscess)
      1. Abscess superior to levator ani
      2. Complicated, deep abscess spread from perianal, intersphincter and Ischiorectal Abscesses
      3. May also spread from Pelvis (PID, Diverticulitis, Ruptured Appendicitis)

VI. Symptoms

  1. Constant, throbbing perianal pain
  2. Pain may be made worse with Defecation
  3. Systemic symptoms (e.g. fever, chills, Nausea, Vomiting) may be present with deep space infection

VII. Signs: General

  1. Palpable, tender mass in perianal area or on rectal exam
    1. Perianal Abscess is superficial and is easily identified as a red, tender fluctuant perianal mass
    2. Deeper, Perirectal Abscesses may only be identified on rectal exam or on imaging
  2. Purulent drainage may be seen via perianal skin tract
    1. See Fistula-in-ano

IX. Imaging

  1. CT Pelvis
    1. Indicated for evaluation of deep space or complicated abscess
      1. Intersphincteric Abscess
      2. Ischiorectal Abscess
      3. Pelvirectal Abscess (Supralevator Abscess)
  2. MRI Pelvis
    1. Indicated for complicated Anal Fistula evaluation
  3. Endorectal Ultrasound
    1. Indicated in some cases of complicated Perirectal Abscess

X. Management

  1. Complete surgical abscess drainage is critical (including breaking up loculations)
    1. See types above for specific approach
    2. Perianal Abscess is typically drained bedside
    3. Deep, Perirectal Abscess is typically drained in the operating room
    4. Perianal Abscess and Ischiorectal Abscess incision should be made as close to anal verge as possible
      1. Minimizes length of potential fistula formation
    5. Wound cultures are not typically useful (polymicrobial)
    6. Wound packing is not typically recommended (does not alter course)
      1. Sterile saline irrigation of the abscess cavity may be performed
      2. However, incision should be long enough to continue to effectively drain
  2. General Measures
    1. Keep area clean and dry
    2. Stool Softeners (e.g. Colace)
    3. Sitz baths
    4. Frequent dressing changes
  3. Antibiotics are recommended to reduce Anal Fistula formation
    1. Treat for 5 day antibiotic course
    2. Additional Indications
      1. Systemic signs of infection
      2. Accompanying Cellulitis
      3. Valvular heart disease
      4. Diabetes Mellitus
      5. Immunocompromised patient
    3. Antibiotic coverage (Anaerobes, Gram Negatives)
      1. See Diverticulitis for nuanced antibiotic coverage (Perianal Abscess is treated the same)
      2. Example Regimens (choose one)
        1. Ciprofloxacin 500 mg orally twice daily AND Metronidazole 500 mg orally three times daily
        2. Amoxicillin-Clavulanate (Augmentin) 875 mg orally twice daily

XI. Complications

  1. Fistula-in-ano (complicates up to 50 to 70% of Perirectal Abscess)
  2. Untreated Anorectal Abscess
    1. Fecal Incontinence
    2. Chronic Pain
    3. Constipation
    4. Recurrent Anorectal Abscess

XII. References

  1. Goroll (2000) Primary Care Medicine, Lippincott, p. 426
  2. Jhun and Cologne in Herbert (2015) EM:Rap 15(9): 17-8
  3. Marx (2002) Rosen's Emergency Medicine, p. 1951
  4. Roberts (1998) Procedures, Saunders, p. 649-51
  5. Sherman, Bahga and Vietvuong (2022) Crit Dec Emerg Med 36(7): 23-9
  6. Surrell in Pfenninger (1994) Procedures, Mosby, p. 969

Images: Related links to external sites (from Bing)

Related Studies

Ontology: Perirectal abscess (C0267566)

Concepts Disease or Syndrome (T047) , Acquired Abnormality (T020)
ICD10 K61.1
SnomedCT 91669008
Italian Ascesso perirettale
Japanese 直腸周囲膿瘍, チョクチョウシュウイノウヨウ
English Perirectal abscesses, perirectal abscess (diagnosis), rectal abscess perirectal, perirectal abscess (physical finding), perirectal abscess, abscesses perirectal, abscess perirectal, peri-rectal abscess, peri rectal abscess, Perirectal abscess, Perirectal abscess (disorder), abscess; perirectal, pararectal; abscess, perirectal; abscess
Czech Perirektální absces
Hungarian perirectalis tályog
Dutch abces; perirectaal, pararectaal; abces, perirectaal; abces, perirectaal abces
Spanish absceso perirrectal (trastorno), absceso perirrectal, Absceso perirrectal
Portuguese Abcesso perirrectal
French Abcès périrectal
German perirektaler Abszess

Ontology: Anorectal abscess (C0267567)

Concepts Disease or Syndrome (T047)
ICD9 566
ICD10 K61 , K61.2
SnomedCT 266530003, 155793007, 155796004, 197167001, 197160004, 75236001
Dutch anorectaal abces, abces anorectaal, abces van anorectale streken, abces; anorectaal, anorectaal; abces, Anorectaal abces, Abces van anaal en rectaal gebied
French Abcès anorectal, Abcès des régions anale et rectale
German Abszess anorektal, anorektaler Abszess, Abszess in der Anal- und Rektalregion, Anorektalabszess, Abszess des analen und rektalen Bereichs
Italian Ascesso anorettale, Ascesso anale e rettale
Portuguese Abcesso anorrectal, Abcesso das regiões anal e rectal
Spanish Absceso anorrectal, Absceso de las regiones anal y rectal, absceso anorrectal, SAI (trastorno), absceso anorrectal, SAI, absceso anorrectal (trastorno), absceso anorrectal
Japanese 肛門直腸膿瘍, コウモンチョクチョウノウヨウ
English Anorectal abscess NOS, Abscess anorectal, Anal & rectal abscess, abscess of anal and rectal regions, Abscess;anorectal, abscesses anorectal, anorectal abscess, abscess anorectal, Anal/rectal abscess, Anal/rectal abscess NOS, Anorectal abscess NOS (disorder), Abscess - anal/rectal, anorectal abscess (diagnosis), Anorectal abscess, Anorectal abscess (disorder), abscess; anorectal, anorectal; abscess, Abscess of anal and rectal regions
Czech Anorektální absces, Absces řitní a konečníkové krajiny
Korean 항문 및 직장부의 고름집(농양), 항문직장 고름집(농양)
Hungarian Analis és rectalis régió abscessusa, anorectalis tályog, anorectalis abscessus