Treatment of Perianal Abscess
Incision and drainage is the definitive treatment for perianal abscess and should be performed promptly—within 24 hours for uncomplicated cases, or emergently if sepsis, immunosuppression, diabetes, or diffuse cellulitis is present. 1, 2
Primary Surgical Management
Complete surgical drainage is essential and represents the cornerstone of treatment for all perianal abscesses. 1, 2
Surgical Technique by Abscess Location
Perianal and ischioanal abscesses: Drain via incision through the overlying skin, keeping the incision as close as possible to the anal verge to minimize potential fistula length while ensuring adequate drainage 1, 2
Intersphincteric abscesses: Drain into the rectal lumen, which may require a limited internal sphincterotomy 1, 2
Supralevator abscesses: Drain via the rectal lumen if it represents extension of an intersphincteric abscess, or externally via the skin if it represents extension of an ischioanal abscess 1, 2
Large abscesses: Use multiple counter incisions rather than a single long incision to avoid step-off deformity and delayed wound healing 1
Why Complete Drainage Matters
Inadequate drainage leads to significantly higher recurrence rates. A randomized trial demonstrated 41% recurrence with needle aspiration compared to only 15% with proper incision and drainage, confirming that complete drainage is non-negotiable. 1, 3
Timing of Surgical Intervention
Emergency Drainage (Immediate)
Perform emergency drainage for patients with: 1, 2
- Sepsis, severe sepsis, or septic shock
- Immunosuppression
- Diabetes mellitus
- Diffuse cellulitis
Urgent Drainage (Within 24 Hours)
For patients without the above risk factors, perform surgical drainage within 24 hours. 1, 2
Anesthesia Considerations
Young, fit patients without signs of sepsis may undergo surgery in an ambulatory setting, and small simple perianal abscesses may be treated under local anesthesia. 1
Management of Concomitant Fistulas
If a fistula is identified during abscess drainage, your approach depends on sphincter involvement: 1, 2
Low fistulas NOT involving sphincter muscle (subcutaneous fistulas): Perform fistulotomy at the time of abscess drainage 1, 2
Fistulas involving ANY sphincter muscle: Place a loose draining seton rather than performing immediate fistulotomy 1, 2
Do NOT probe for fistulas if none is obvious, as this risks iatrogenic complications 1
Evidence Supporting Selective Fistula Treatment
Meta-analysis of six trials involving 479 patients showed that fistula surgery with abscess drainage significantly reduces recurrence (RR=0.13,95% CI 0.07-0.24), but this benefit must be balanced against the risk of incontinence in patients who may never have developed a fistula. 4 This is why the selective approach based on sphincter involvement is recommended.
Post-Operative Wound Management
Wound packing after drainage is NOT recommended. 1, 2
The evidence is clear on this controversial practice:
- A Cochrane review found it unclear whether packing influences healing time, pain, fistula development, or recurrence 1
- A multi-center observational study of 141 patients concluded that packing is costly, painful, and does not benefit the healing process 1, 2
- Individual unit policy may vary, but the weight of evidence does not support routine packing 1
Antibiotic Therapy
Antibiotics are NOT routinely indicated after adequate surgical drainage. 2
When to Use Antibiotics
Consider antibiotics ONLY in these specific situations: 1, 2
- Sepsis and/or surrounding soft tissue infection with significant cellulitis
- Immunocompromised patients
- Incomplete source control
- High-risk patients (diabetes, immunosuppression)
Antibiotic Selection When Indicated
Use empiric broad-spectrum coverage including Gram-positive, Gram-negative, and anaerobic bacteria. 1 Consider MRSA coverage if clinically suspected based on local prevalence. 1
Common Pitfalls to Avoid
- Inadequate drainage: This is the primary cause of recurrence—ensure complete evacuation of all loculations 1, 3
- Probing for occult fistulas: This causes iatrogenic injury without proven benefit 1
- Routine wound packing: This adds cost and pain without improving outcomes 1, 2
- Routine antibiotics: These are unnecessary after adequate drainage in immunocompetent patients without cellulitis 2
- Long single incisions: Use multiple counter incisions for large abscesses to prevent deformity 1
- Delayed surgery: Timing matters—drain within 24 hours or emergently based on clinical factors 1, 2