Treatment of Perineal Abscess
Immediate surgical incision and drainage is the definitive treatment for perineal abscess, with antibiotics reserved only for patients with systemic infection, immunocompromised status (including diabetes), significant surrounding cellulitis, or incomplete source control. 1
Primary Management: Surgical Drainage
Incision and drainage must be performed promptly after diagnosis to prevent expansion into adjacent spaces and progression to systemic infection. 1, 2
Timing of Surgery
Emergency drainage (within hours) is required for patients with:
Outpatient management may be considered only for fit, immunocompetent patients with small perianal abscesses without systemic signs 1
Surgical Technique
- Keep the incision as close as possible to the anal verge to minimize potential fistula length while ensuring adequate drainage 2
- Use multiple counter incisions for large abscesses rather than a single long incision, which creates step-off deformity and delays healing 1, 2
- Complete drainage is essential—inadequate drainage is associated with recurrence rates up to 44% 2, 3
- Evacuate all loculations thoroughly 2, 3
Antibiotic Therapy: Limited Indications Only
Antibiotics are NOT routinely indicated after adequate surgical drainage. 1, 4
Specific Indications for Antibiotics
Add antibiotics ONLY when:
- Systemic signs of infection or sepsis are present 1
- Patient is immunocompromised (including diabetes) 1
- Significant surrounding soft tissue infection or cellulitis exists 1
- Source control is incomplete 1, 2
Antibiotic Selection When Indicated
Use empiric broad-spectrum coverage for Gram-positive, Gram-negative, and anaerobic bacteria, as these infections are frequently polymicrobial. 1, 2, 5
- Perianal abscesses originate from obstructed anal crypt glands and involve mixed flora from skin, bowel, and occasionally vaginal sources 1, 4
- Consider MRSA coverage in high-prevalence areas 1
- Sample drained pus in high-risk patients or when multidrug-resistant organisms are suspected 1
Special Considerations for High-Risk Patients
Diabetic Patients
- Check serum glucose, hemoglobin A1c, and urine ketones to identify undetected diabetes or assess control 1
- Poor glycemic control significantly increases risk for perianal abscess and complications 6
- Diabetic patients are at higher risk for extensive necrotizing infections if drainage is inadequate 7, 8
- More aggressive early intervention is warranted in this population 7
Immunocompromised Patients
- Lower threshold for antibiotic therapy 1
- Consider more urgent surgical timing 2
- Monitor closely for progression to necrotizing fasciitis (Fournier's gangrene) 8
Management of Concomitant Fistulas
If an obvious fistula is identified during abscess drainage:
- Perform fistulotomy only for low fistulas NOT involving sphincter muscle (subcutaneous fistulas) 1, 2
- Place a loose draining seton for fistulas involving any sphincter muscle 1, 2
- Do NOT probe to search for possible fistula if none is obvious—this risks iatrogenic complications 1
Treating the fistula at the time of abscess drainage significantly reduces recurrence (RR=0.13) without statistically significant increase in incontinence at one year. 9
Post-Operative Care
- Wound packing is controversial—some evidence suggests it may be costly and painful without adding benefit 2, 3
- Routine imaging after drainage is NOT required 2, 3
- Consider follow-up imaging only for recurrence, suspected inflammatory bowel disease, or evidence of non-healing wound 2, 3
Common Pitfalls to Avoid
- Never rely on antibiotics alone without surgical drainage—this leads to progression of infection 5
- Avoid narrow-spectrum antibiotics (like amoxicillin-clavulanate alone) when broader polymicrobial coverage is needed 5
- Do not delay surgical intervention while attempting medical management 5
- Ensure complete drainage of all loculations—inadequate drainage is the primary cause of recurrence 2, 3