II. Epidemiology
- Represents 60% of Perirectal Abscess
III. Pathophysiology
- Local Perirectal Abscess adjacent to anal verge
- Infection spreads distally from the intersphincteric groove
IV. Signs
- Superficial tender fluctuant perianal mass
- Immediately adjacent to anal verge
- Abscess limited to perianal subcutaneous tissue
- Digital Rectum exam red flags for deep space infection (consider CT Pelvis and surgery Consultation)
- Significant intolerance to Rectal Exam (chandelier sign)
- Bogginess, tenderness, induration superior to the anal sphincter (supralevator space)
-
Anoscopy
- Fistula opening with drainage
V. Associated Conditions
- Fistula-in-ano (50% of cases)
VI. Differential Diagnosis
- Ischiorectal Abscess (2-3 cm from anal verge)
- Deep Perirectal Abscess
VII. Management: Incision and Drainage
- See Perirectal Abscess
- Precautions
- Visible abscess (red, swollen pocket) may be drained
- Imaging and surgical Consultation is indicated if the abscess pocket can not easily be seen
- Local Incision and Drainage directed away from Rectum
- Wear Personal Protective Equipment (including mask)
- Prepare the skin in typical fashion (Povidone Iodine or Chlorhexidine and draped)
- Local Anesthetic (marginal efficacy)
- Use 18 gauge needle to localize the abscess pocket
- Localizes site of incision
- Incise (#11 or #15 Blade) into fluctuant area near anal verge
- Avoid incising sphincter
- However place incision close to anal verge (avoids longer tract fistula complications)
- Direct incision in plane radial to anus
- Irrigate abscess cavity with saline
- Ensure continued patent drainage
- Eliptical incision (1 cm long) or
- Insert gauze or penrose drain (Suture in place)
VIII. Management: Surgical Referral Indications
- Failed improvement within 24 hours of drainage
- Signs of abscess extension
- Underlying hematologic disease
- Evaluation at one week for Fistula-in-ano
- Recurrent Perianal Abscess
- Consider underlying causes (Crohn Disease, HIV Infection)
IX. Follow-up
- Re-examine in 24 hours for improvement
X. References
- Jhun and Cologne in Herbert (2015) EM:Rap 15(9): 17-8
- Marx (2002) Rosen's Emergency Medicine, p. 1952
- Roberts (1998) Procedures, Saunders, p. 649-51
- Sherman, Bahga and Vietvuong (2022) Crit Dec Emerg Med 36(7): 23-9
- Surrell in Pfenninger (1994) Procedures, Mosby, p. 969
- Cohee (2020) Am Fam Physician 101(1):24-33 [PubMed]