Perianal Abscess

Aka: Perianal Abscess

1. See Also
   1. Perirectal Abscess
2. Epidemiology
   1. Represents 60% of Perirectal Abscess
3. Pathophysiology
   1. Local Perirectal Abscess adjacent to anal verge
4. 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
5. Associated Conditions
   1. Fistula-in-ano (50% of cases)
6. Differential Diagnosis
   1. Ischiorectal Abscess (2-3 cm from anal verge)
   2. Deep Perirectal Abscess
7. 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. Local Anesthetic (marginal efficacy)
      2. Use 18 gauge needle to localize the abscess pocket
         1. Localizes site of incision
      3. Incise into fluctuant area near anal verge
         1. Avoid incising sphincter
         2. However place incision close to anal verge (avoids longer tract fistula complications)
      4. Direct incision in plane radial to anus
      5. Irrigate abscess cavity with saline
      6. Ensure continued patent drainage
         1. Eliptical incision (1 cm long) or
         2. Insert gauze or penrose drain (Suture in place)
8. 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)
9. Follow-up
   1. Re-examine in 24 hours for improvement
10. 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. Surrell in Pfenninger (1994) Procedures, Mosby, p. 969
    5. Cohee (2020) Am Fam Physician 101(1):24-33 [PubMed]