What is the treatment for a peri-anal abscess?

Treatment of Perianal Abscess

Incision and drainage is the cornerstone of treatment for all perianal abscesses and should be performed urgently, ideally within 24 hours unless the patient has sepsis, immunosuppression, diabetes, or diffuse cellulitis—in which case emergency drainage is mandatory. 1, 2

Immediate Surgical Management

Timing and Setting

• Emergency drainage (cannot wait) is required for patients presenting with:
  • Sepsis, severe sepsis, or septic shock 2
  • Immunosuppression or diabetes mellitus 2
  • Diffuse cellulitis 2
• For stable, immunocompetent patients without systemic signs, drainage should still occur within 24 hours 2
• Small perianal abscesses in fit, immunocompetent patients without systemic sepsis can be managed in an outpatient setting 1
• Deeper or more complex abscesses require operating room drainage 1

Surgical Technique

• Make the incision as close as possible to the anal verge to minimize the length of any potential fistula tract while ensuring adequate drainage 1, 2
• For larger abscesses, use multiple counter incisions rather than a single long incision to prevent delayed wound healing 1
• Complete drainage is essential—inadequate drainage is the primary risk factor for recurrence 2
• Location-specific approach: perianal and ischioanal abscesses drain via overlying skin; intersphincteric and supralevator abscesses drain via the rectal lumen 2

Management of Concomitant Fistulas

During the drainage procedure, examine for associated fistula tracts 1:

• If a low fistula NOT involving sphincter muscle is identified: perform fistulotomy at the time of abscess drainage 1, 2
• If the fistula involves ANY sphincter muscle: place a loose draining seton rather than performing immediate fistulotomy to prevent incontinence 1, 2
• This approach is supported by evidence showing that treating low fistulas at the time of drainage significantly reduces recurrence (RR=0.13) without statistically significant incontinence risk 3

Diagnostic Imaging

When to Image

• Clinical diagnosis alone is sufficient for typical perianal abscesses 2
• Order imaging (CT, MRI, or endosonography) for: 1, 2
  • Atypical presentation
  • Suspected deep supralevator or intersphincteric abscesses
  • Suspected inflammatory bowel disease (particularly Crohn's disease)
  • Multiple suspected collections
• Do not delay drainage if imaging is not immediately available when a perianal abscess is clinically suspected 4
• MRI is the gold standard for perianal fistulizing Crohn's disease with 76-100% accuracy 4

Antibiotic Therapy

Antibiotics are NOT routinely indicated after adequate surgical drainage in immunocompetent patients. 1, 2

Indications for Antibiotics

Prescribe antibiotics ONLY when: 1, 2

• Systemic signs of infection or sepsis are present
• Patient is immunocompromised
• Incomplete source control achieved
• Significant surrounding cellulitis exists
• High-risk patients (diabetes, immunosuppression)

Antibiotic Selection

When indicated, use empiric broad-spectrum coverage targeting Gram-positive, Gram-negative, and anaerobic bacteria 1

Post-Operative Wound Care

Wound Packing

• The role of routine wound packing remains controversial 5
• Evidence suggests packing may be costly and painful without clear benefit to healing 2, 5
• One small study showed no clear difference in healing time between packed (26.8 days) and non-packed wounds (19.5 days) 5

Follow-Up and Monitoring

Surveillance Strategy

• Close follow-up is essential to monitor for recurrence or fistula development 1
• Routine imaging after drainage is NOT required 1, 2
• Order follow-up imaging only for: 1, 2
  • Recurrence of abscess
  • Suspected inflammatory bowel disease
  • Evidence of fistula or non-healing wound

Recurrence Risk Factors

Be aware that recurrence rates can reach 44%, with higher risk in patients with: 1

• Inadequate initial drainage
• Loculations
• Horseshoe-type abscess
• Delayed time from symptom onset to incision

Special Considerations for Crohn's Disease

If perianal Crohn's disease is suspected or confirmed: 4

• Perform endoscopic assessment of the rectum to determine management strategy
• Proctitis is a predictive factor for persistent non-healed fistula tracts and higher proctectomy rates
• Examination under anesthesia with abscess drainage and seton placement before starting anti-TNF therapy achieves higher success rates and lower recurrence rates
• Consider MRI for detailed visualization of fistula tracts, sphincter involvement, and silent abscesses