What is the treatment for recurring perianal abscess?

Treatment for Recurring Perianal Abscess

For recurring perianal abscesses, perform immediate repeat incision and drainage with complete evacuation of all pus and loculations, followed by mandatory investigation for an underlying fistula tract using MRI or examination under anesthesia, as approximately one-third of perianal abscesses have an associated fistula that dramatically increases recurrence risk. 1

Immediate Surgical Management

Complete surgical drainage is non-negotiable and must be performed urgently:

• Perform incision and drainage as close as possible to the anal verge to minimize potential fistula tract length while ensuring adequate drainage 1, 2
• Thoroughly evacuate all pus and actively probe the cavity to break up loculations, as incomplete drainage is the leading cause of recurrence with rates as high as 44% 1, 3
• Emergency drainage (immediate) is required if the patient has:
  • Sepsis, severe sepsis, or septic shock 1, 3
  • Immunosuppression or diabetes mellitus 1, 3
  • Diffuse cellulitis 1, 2
• In the absence of high-risk features, perform drainage within 24 hours 1, 3

Investigation for Underlying Fistula

The recurrent nature of this abscess significantly raises suspicion for an unaddressed fistula tract:

• Approximately one-third of perianal abscesses have an associated fistula-in-ano, which dramatically increases recurrence risk 1
• For recurrent abscesses, imaging follow-up is specifically recommended to identify fistula tracts 1
• Contrast-enhanced pelvic MRI is the gold standard for assessment of perianal fistulizing disease with 76-100% accuracy 4, 2
• Examination under anesthesia (EUA) by an experienced colorectal surgeon is considered the gold standard for identifying fistula anatomy 4
• Combination of MRI and EUA provides optimal assessment, as MRI may miss small abscesses while EUA may miss supralevator collections 4

Fistula Management at Time of Drainage

If a fistula is identified during drainage, treatment depends on anatomic complexity:

• For low fistulas NOT involving sphincter muscle (subcutaneous fistulas), perform immediate fistulotomy 1, 2
  • Meta-analysis shows fistula surgery with abscess drainage significantly reduces recurrence (RR=0.13,95% CI 0.07-0.24) 5
  • Studies in children show 0% recurrence with fistulotomy vs. 21-100% recurrence with drainage alone 6, 7
• For any fistula involving sphincter muscle, place a loose draining seton rather than performing fistulotomy to avoid incontinence risk 1, 2
• Do NOT blindly probe or use hydrogen peroxide to search for fistulas if not clinically obvious, as this causes iatrogenic complications 1

Antibiotic Therapy

Antibiotics are indicated for recurrent abscesses in specific circumstances:

• Use antibiotics when there is:
  • Sepsis or systemic signs of infection 1, 2
  • Surrounding soft tissue infection or significant cellulitis 1, 2
  • Immunocompromised state 1, 2
  • Inadequate source control despite drainage 1, 2
• Use empiric broad-spectrum coverage targeting Gram-positive (including MRSA), Gram-negative, and anaerobic bacteria, as these abscesses are frequently polymicrobial 1, 2
• Consider metronidazole and/or ciprofloxacin for perianal fistulizing disease, particularly if Crohn's disease is suspected 4
• A 5-10 day course following drainage may reduce fistula formation by 36% in patients with surrounding cellulitis or systemic sepsis 1
• Note: Recent randomized trial showed antibiotics do NOT reduce fistula formation or abscess recurrence in uncomplicated cases (16.3% vs 10.2%, p=0.67) 8

Evaluation for Crohn's Disease

Recurrent perianal abscesses mandate evaluation for inflammatory bowel disease:

• Consider Crohn's disease in all patients with recurrent perianal/gluteal abscesses 1, 2
• Perform proctosigmoidoscopy routinely in the initial evaluation, as concomitant rectosigmoid inflammation has prognostic and therapeutic relevance 4
• The presence of proctitis predicts persistent non-healed fistula tracts and higher proctectomy rates (29% vs 4%) 4
• If Crohn's disease is confirmed, seton placement combined with antibiotics (metronidazole and/or ciprofloxacin) is the preferred strategy 4
• For refractory disease not responding to antibiotics, thiopurines or anti-TNF agents (infliximab or adalimumab) should be used as second-line therapy 4

Post-Operative Management

• The role of wound packing remains controversial and cannot be strongly recommended, as evidence suggests it may be costly and painful without adding benefit 1, 3, 2
• If packing is used, remove within 24 hours and change regularly until cavity heals 1
• Re-evaluate at 7 days - persistent fever or failure to improve indicates inadequate source control requiring repeat imaging or intervention 1

Common Pitfalls to Avoid

• Do NOT perform simple needle aspiration - this has a 41% recurrence rate compared to 15% with proper incision and drainage 1, 3
• Do NOT create one long incision for large abscesses - use multiple counter incisions to avoid step-off deformity and delayed healing 1, 2
• Do NOT perform fistulotomy on high fistulas involving sphincter muscle at initial drainage, as this risks incontinence 1, 2
• Rule out diabetes mellitus in all patients with recurrent abscesses 1