Treatment of Perianal Abscess
Incision and drainage is the definitive treatment for a perianal abscess that appears internal, and this should be performed urgently—within 24 hours for most patients, or emergently if sepsis, immunosuppression, diabetes, or diffuse cellulitis is present. 1, 2
Immediate Surgical Management
The cornerstone of treatment is adequate surgical drainage, as antibiotics alone will not cure an undrained abscess. 1, 2
- Make the incision as close to the anal verge as possible to minimize potential fistula length while ensuring complete drainage 1, 2
- Complete drainage is critical—inadequate drainage is the primary cause of recurrence rates up to 44% 1, 2
- For larger abscesses, use multiple counter incisions rather than a single long incision to prevent step-off deformity and delayed healing 1, 2
- During drainage, examine for an associated fistula tract 2
Management of Identified Fistulas
If you identify a fistula during abscess drainage:
- Perform fistulotomy only for low fistulas that do not involve sphincter muscle 1, 2
- Place a loose draining seton for any fistula involving sphincter muscle to prevent incontinence 1, 2
- Do not perform immediate fistulotomy on complex fistulas—this significantly increases incontinence risk 3
Timing Considerations
Emergency drainage (immediate) is mandatory for: 1
- Sepsis, severe sepsis, or septic shock
- Immunosuppressed patients
- Diabetic patients
- Diffuse cellulitis
For all other patients, perform drainage within 24 hours 1
Antibiotic Therapy
Antibiotics are NOT routinely indicated after adequate surgical drainage in immunocompetent patients. 1, 2
Use antibiotics only when: 1, 2
- Systemic signs of infection or sepsis are present
- Significant surrounding cellulitis exists
- Incomplete source control
- Patient is immunocompromised
- Patient has diabetes mellitus
When antibiotics are indicated, use empiric broad-spectrum coverage for Gram-positive, Gram-negative, and anaerobic bacteria, as these infections are polymicrobial 1, 2
Post-Operative Care
- Wound packing after drainage is controversial and may be painful without adding benefit—consider avoiding it 1
- Close follow-up is essential to monitor for recurrence or fistula development 2
- Routine imaging after drainage is not required unless there is recurrence, suspected inflammatory bowel disease, or evidence of non-healing wound 1, 2
High-Risk Patients Requiring Special Attention
Patients with the following conditions have significantly increased recurrence risk and may benefit from senior surgeon involvement: 4, 5
- Inflammatory bowel disease (especially Crohn's disease)
- Diabetes mellitus
- Malignancy
- Immunosuppression
- Horseshoe-type abscess
- Loculated abscess
For suspected Crohn's disease, perform endoscopic assessment of the rectum, as proctitis predicts persistent non-healed fistula tracts and higher proctectomy rates 1
Common Pitfalls to Avoid
- Do not delay drainage waiting for imaging—clinical diagnosis is sufficient for typical presentations 1
- Do not perform aggressive fistulotomy at initial drainage unless it's clearly a low, simple fistula not involving sphincter 1, 2
- Do not prescribe antibiotics routinely—they are not a substitute for adequate drainage 1, 2
- Do not make inadequate incisions—incomplete drainage is the leading cause of 31-44% recurrence rates 1, 4