What is the treatment for a perineal abscess?

Treatment of Perineal Abscess

Immediate incision and drainage is the definitive treatment for all perineal abscesses and should be performed within 24 hours in stable patients, or emergently in those with sepsis, immunosuppression, diabetes, or diffuse cellulitis. 1, 2

Timing of Surgical Intervention

• Emergency drainage is mandatory for patients presenting with sepsis, severe sepsis, septic shock, immunosuppression, diabetes mellitus, or diffuse cellulitis 1
• In stable, immunocompetent patients without systemic signs, drainage should ideally occur within 24 hours of diagnosis 1
• Do not delay drainage waiting for imaging if a perianal abscess is clinically suspected—proceed directly to examination under anesthesia with drainage 3, 1

Surgical Technique

• Place the incision as close to the anal verge as possible to minimize potential fistula tract length while ensuring complete drainage 1, 2, 4
• For larger abscesses, create multiple counter incisions rather than a single long incision to prevent step-off deformity and delayed wound healing 1, 4
• Complete drainage is essential, as inadequate drainage is the primary risk factor for recurrence rates up to 44% 1, 2

Management of Concomitant Fistulas

If an obvious fistula is identified during drainage, your approach depends on sphincter involvement:

• For low fistulas NOT involving sphincter muscle: perform immediate fistulotomy at the time of abscess drainage, which reduces recurrence from 44% (drainage alone) to 21.1% 1, 4, 5
• For fistulas involving ANY sphincter muscle: place a loose draining seton rather than performing fistulotomy to prevent fecal incontinence 1, 2, 4

The evidence strongly supports this approach—meta-analysis demonstrates significant reduction in recurrence with fistula treatment at initial drainage (RR=0.13,95% CI 0.07-0.24) without statistically significant increase in incontinence 5

Setting for Procedure

• Fit, immunocompetent patients with small perianal abscesses and no systemic sepsis may undergo bedside drainage in the emergency department, which significantly shortens time to intervention (2.13 vs. 10.41 hours) without increasing complications 2, 6
• Deeper or more complex abscesses (ischiorectal, intersphincteric, supralevator) require drainage in the operating room under adequate anesthesia to allow thorough examination 2, 4

Antibiotic Therapy

Antibiotics are NOT routinely indicated after adequate surgical drainage in immunocompetent patients. 1, 2, 4

Prescribe antibiotics ONLY when:

• Systemic signs of infection or sepsis are present 1, 2, 4
• Patient is immunocompromised 1, 2, 4
• Incomplete source control after drainage 1, 2
• Significant surrounding cellulitis extending beyond abscess borders 1, 4

When antibiotics are indicated, use empiric broad-spectrum coverage targeting Gram-positive, Gram-negative, and anaerobic bacteria, as these infections are polymicrobial 1, 2, 4

Imaging Considerations

• Clinical diagnosis is usually sufficient for typical perianal abscesses 1
• Consider imaging (CT or MRI) for atypical presentations, suspected deep supralevator or intersphincteric abscesses, or suspected Crohn's disease 1, 2
• MRI is the gold standard for perianal fistulizing Crohn's disease with 76-100% accuracy 3, 1
• If Crohn's disease is suspected, perform endoscopic assessment of the rectum, as proctitis predicts persistent non-healed fistula tracts and higher proctectomy rates 3, 1

Post-Operative Care and Follow-Up

• Wound packing after drainage remains controversial, with some evidence suggesting it may be costly and painful without benefit 1
• Routine imaging after drainage is NOT required unless there is recurrence, suspected inflammatory bowel disease, or evidence of fistula/non-healing wound 1, 2
• Close follow-up is essential to monitor for recurrence or fistula development 2, 4

Critical Pitfalls to Avoid

• Never rely on antibiotics alone without drainage—this will fail and allow progression to deeper infection or necrotizing fasciitis 4, 7
• Do not perform immediate fistulotomy if significant sphincter muscle is involved—this risks permanent fecal incontinence 1, 2, 4
• Do not prescribe antibiotics routinely after adequate drainage in healthy patients—this is unnecessary and promotes antibiotic resistance 1, 2, 4
• Be vigilant for progression to Fournier's gangrene, particularly in patients with diabetes, hidradenitis suppurativa, or immunosuppression—these require aggressive early debridement 7