What is the treatment for a perianal abscess?

Treatment of Perianal Abscess

Incision and drainage is the definitive treatment for all perianal abscesses and should be performed within 24 hours of diagnosis, or emergently if the patient has sepsis, immunosuppression, diabetes, or diffuse cellulitis. 1, 2

Surgical Management: The Cornerstone of Treatment

Timing of Drainage

• Emergency drainage (immediate) is mandatory for: 1, 2
  • Sepsis, severe sepsis, or septic shock
  • Immunosuppressed patients
  • Diabetic patients
  • Diffuse cellulitis
• Urgent drainage (within 24 hours) for all other cases 1, 2
• Do not delay drainage waiting for imaging if clinical diagnosis is clear 1

Surgical Technique

• Keep the incision as close as possible to the anal verge to minimize potential fistula tract length while ensuring adequate drainage 1, 2
• Use multiple counter incisions for large abscesses rather than one long incision, which creates step-off deformity and delays healing 3, 1
• Complete drainage is essential—inadequate drainage is the primary cause of recurrence (up to 44% with loculations) 1, 2
• Approach varies by abscess location: 1
  • Perianal and ischioanal abscesses: drain via overlying skin
  • Intersphincteric abscesses: drain via rectal lumen
  • Supralevator abscesses: drain via rectal lumen or externally through skin

Management of Concomitant Fistulas

• If an obvious fistula is identified during drainage: 1, 2
  • Perform fistulotomy only for low fistulas not involving sphincter muscle
  • Place a loose draining seton for any fistula involving sphincter muscle
• This approach significantly reduces recurrence (RR=0.13,95% CI 0.07-0.24) without statistically significant increase in incontinence 4

Antibiotic Therapy: Limited Role

Antibiotics are NOT routinely indicated after adequate surgical drainage. 1, 2, 5

Indications for Antibiotics (use only when present):

• Systemic signs of infection or sepsis 3, 1, 2
• Significant surrounding cellulitis 3, 1, 2
• Immunocompromised patients 3, 1
• Incomplete source control 3, 1

Antibiotic Selection (when indicated):

• Use empiric broad-spectrum coverage for Gram-positive, Gram-negative, and anaerobic bacteria, as these infections are frequently polymicrobial 3, 1, 2

Post-Operative Care

Wound Management

• Wound packing remains controversial—some evidence suggests it may be costly and painful without adding benefit to healing 1, 2
• Consider corrugated rubber drain as an alternative, which provides better pain control (pain score 2/10 vs 8/10) and lower recurrence rates compared to packing 6

Follow-Up

• Routine imaging after drainage is NOT required 1, 2
• Consider follow-up imaging only for: 1, 2
  • Recurrence
  • Suspected inflammatory bowel disease (especially Crohn's disease)
  • Evidence of fistula or non-healing wound

Special Considerations and Pitfalls

Risk Factors for Recurrence

• Inadequate drainage (most important modifiable factor) 1, 2
• Loculations (44% recurrence rate) 1
• Horseshoe-type abscess 1
• Delayed time from disease onset to incision 1

Crohn's Disease Considerations

• If perianal Crohn's disease is suspected, perform endoscopic assessment of the rectum to guide management 1
• Proctitis predicts persistent non-healed fistula tracts and higher proctectomy rates 1
• Control sepsis prior to definitive surgery; consider percutaneous drainage for intra-abdominal abscesses as first-line treatment 3

Uncommon Causes

• Consider ingested foreign bodies as an unusual cause—digital rectal examination and proctoscopy may be needed to identify impacted foreign bodies 7
• One-third of patients have an underlying fistula; if suspected, referral to a fistula center is warranted 8