II. Epidemiology

  1. Represents 60% of Perirectal Abscess

III. Pathophysiology

  1. Local Perirectal Abscess adjacent to anal verge
  2. Infection spreads distally from the intersphincteric groove

IV. Signs

  1. Superficial tender fluctuant perianal mass
    1. Immediately adjacent to anal verge
    2. Abscess limited to perianal subcutaneous tissue
  2. Digital Rectum exam red flags for deep space infection (consider CT Pelvis and surgery Consultation)
    1. Significant intolerance to rectal exam (chandelier sign)
    2. Bogginess, tenderness, induration superior to the anal sphincter (supralevator space)
  3. Anoscopy
    1. Fistula opening with drainage

V. Associated Conditions

  1. Fistula-in-ano (50% of cases)

VI. Differential Diagnosis

  1. Ischiorectal Abscess (2-3 cm from anal verge)
  2. Deep Perirectal Abscess

VII. Management: Incision and Drainage

  1. See Perirectal Abscess
  2. Precautions
    1. Visible abscess (red, swollen pocket) may be drained
    2. Imaging and surgical Consultation is indicated if the abscess pocket can not easily be seen
  3. Local Incision and Drainage directed away from Rectum
    1. Wear Personal Protective Equipment (including mask)
    2. Prepare the skin in typical fashion (Povidone Iodine or Chlorhexidine and draped)
    3. Local Anesthetic (marginal efficacy)
    4. Use 18 gauge needle to localize the abscess pocket
      1. Localizes site of incision
    5. Incise (#11 or #15 Blade) into fluctuant area near anal verge
      1. Avoid incising sphincter
      2. However place incision close to anal verge (avoids longer tract fistula complications)
    6. Direct incision in plane radial to anus
    7. Irrigate abscess cavity with saline
    8. Ensure continued patent drainage
      1. Eliptical incision (1 cm long) or
      2. Insert gauze or penrose drain (Suture in place)

VIII. Management: Surgical Referral Indications

  1. Failed improvement within 24 hours of drainage
  2. Signs of abscess extension
  3. Underlying hematologic disease
  4. Evaluation at one week for Fistula-in-ano
  5. Recurrent Perianal Abscess
    1. Consider underlying causes (Crohn Disease, HIV Infection)

IX. Follow-up

  1. Re-examine in 24 hours for improvement

X. References

  1. Jhun and Cologne in Herbert (2015) EM:Rap 15(9): 17-8
  2. Marx (2002) Rosen's Emergency Medicine, p. 1952
  3. Roberts (1998) Procedures, Saunders, p. 649-51
  4. Sherman, Bahga and Vietvuong (2022) Crit Dec Emerg Med 36(7): 23-9
  5. Surrell in Pfenninger (1994) Procedures, Mosby, p. 969
  6. Cohee (2020) Am Fam Physician 101(1):24-33 [PubMed]

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Ontology: Perianal abscess (C0031019)

Definition (NCI) An abscess that develops in the soft tissues surrounding the anal canal. Causes include bacterial and fungal infections, malignancies that involve the perianal region, and Crohn disease.
Concepts Disease or Syndrome (T047)
ICD10 K61.0
SnomedCT 155794001, 197161000, 82127005
English ABSCESS PERIANAL, perianal abscess (diagnosis), perianal abscess, Abscess perianal, Abscess;perianal, abscesses perianal, abscess perianal, Perianal Abscess, Perianal abscess (disorder), perianal; abscess, Perianal abscess
Spanish Absceso perianal, absceso perianal (trastorno), absceso perianal
Dutch perianaal abces, abces perianaal, perianaal; abces
Italian Ascesso perianale
German Abszess perianal, perianaler Abszess
French Abcès péri-anal
Portuguese Abcesso perianal
Czech Perianální absces
Japanese コウモンシュウイノウヨウ, 肛門周囲膿瘍
Hungarian perianalis tályog, Perianalis abscessus