What is the treatment for a peri-anal abscess?

Treatment of Perianal Abscess

Incision and drainage is the definitive treatment for perianal abscess and should be performed emergently in patients with sepsis, immunosuppression, diabetes, or diffuse cellulitis, and within 24 hours for all other cases. 1, 2

Surgical Drainage Technique

The cornerstone of treatment is complete surgical drainage, as inadequate drainage leads to recurrence rates up to 44%. 2, 3

Location-specific drainage approaches:

• 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 1, 2, 3
• Intersphincteric abscesses: Drain into the rectal lumen; may require limited internal sphincterotomy 1, 2, 3
• Supralevator abscesses: Drain via rectal lumen if extension of intersphincteric abscess, or externally via skin if extension of ischioanal abscess 1, 2, 3

Incision and drainage is superior to needle aspiration, with recurrence rates of 15% versus 41% respectively. 1, 3

Timing of Surgery

Emergency drainage (immediate) is required for: 2, 3

• Sepsis, severe sepsis, or septic shock
• Immunosuppression
• Diabetes mellitus
• Diffuse cellulitis

For all other patients: Perform surgical drainage within 24 hours 1, 2, 3

Setting of Care

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, 3

Management of Concomitant Fistulas

Approximately one-third of perianal abscesses have an associated fistula-in-ano. 1

If an obvious fistula is identified during drainage: 1, 2

• Low fistulas not involving sphincter muscle (subcutaneous): Perform fistulotomy at the time of abscess drainage
• Fistulas involving any sphincter muscle: Place a loose draining seton only

Do NOT probe for fistulas if none is obvious, as this risks iatrogenic complications. 1

The evidence shows fistula surgery with abscess drainage significantly reduces recurrence (RR=0.13,95% CI 0.07-0.24) without statistically significant incontinence at one year. 4 However, guidelines recommend a conservative approach, reserving fistulotomy only for low, simple fistulas to avoid sphincter injury. 1, 2

Post-Operative Wound Packing

Wound packing after drainage is NOT recommended. 2

The evidence is clear that packing is costly, painful, and does not add benefit to the healing process. 1, 2 A Cochrane review found no clear difference in time to healing, and subsequent observational studies confirmed packing provides no benefit. 1, 5 While some practitioners use packing for hemostasis or to prevent premature skin closure, the available evidence does not support routine use. 1, 5

Antibiotic Therapy

Antibiotics are NOT routinely indicated after adequate surgical drainage. 2

Consider antibiotics only in specific circumstances: 2

• Sepsis and/or surrounding soft tissue infection
• Immunosuppression or other disturbances of immune response
• High-risk patients (diabetes, extensive cellulitis)

Follow-Up and Recurrence Prevention

Routine imaging after incision and drainage is not required. 2, 3

Consider follow-up imaging for: 2, 3

• Recurrence
• Suspected inflammatory bowel disease (Crohn's disease)
• Evidence of fistula or non-healing wound

Risk factors for recurrence include: 2, 3

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

Common Pitfalls

The most critical error is incomplete drainage, which dramatically increases recurrence rates. 1, 2, 3 Avoid probing for fistulas when none is obvious, as this creates iatrogenic injury. 1 Do not delay surgery in high-risk patients (sepsis, diabetes, immunosuppression), as these require emergency drainage. 1, 2, 3