What is the treatment for a perianal abscess?

Treatment of Perianal Abscess

The primary treatment for perianal abscess is surgical incision and drainage, which should be performed promptly to prevent complications and reduce morbidity. 1

Diagnosis and Assessment

• Clinical diagnosis is usually sufficient, based on patient history and physical examination showing pain, swelling, and tenderness in the perianal region 1
• Imaging studies (CT, MRI, or endosonography) should be considered in cases with atypical presentation, suspected deep supralevator abscesses, or in patients with suspected inflammatory bowel disease 2
• Examination under anesthesia (EUA) has an important role in diagnosis and classification of perianal abscesses, with experienced colorectal surgeons achieving up to 90% accuracy 1

Surgical Management

• Incision and drainage is the cornerstone of treatment for all perianal abscesses 1
• The incision should be kept as close as possible to the anal verge to minimize the length of a potential fistula while ensuring adequate drainage 1
• For larger abscesses, multiple counter incisions are preferred over a single long incision to prevent delayed wound healing 1
• During the procedure, examination should be performed to identify any associated fistula tract 2
• If a low fistula not involving sphincter muscle is identified, fistulotomy can be performed at the time of abscess drainage 2, 3
• For fistulas involving sphincter muscle, a loose draining seton should be placed rather than performing immediate fistulotomy to prevent incontinence 2

Timing of Surgery

• The timing for surgery is dictated by the patient's clinical condition 1:
  • Emergent drainage is indicated in patients with sepsis, severe sepsis or septic shock, immunosuppression, diabetes mellitus, or diffuse cellulitis 1
  • In the absence of these factors, surgical drainage should ideally be performed within 24 hours 1

Setting for Drainage Procedure

• Fit, immunocompetent patients with small perianal abscesses and without systemic signs of sepsis may be managed in an outpatient setting 1
• Deeper or more complex abscesses may require more extensive drainage in an operating room setting 2
• Different types of abscesses require different approaches 1:
  • Perianal and ischioanal abscesses should be treated via incision and drainage of the overlying skin
  • Intersphincteric abscess should be drained into the rectal lumen and may require limited internal sphincterotomy
  • Supralevator abscess may require drainage via the rectal lumen (if extension of an intersphincteric abscess) or externally via the skin (if extension of ischioanal abscess)

Post-Operative Care

• Recent evidence suggests that avoiding abscess cavity packing is less painful without increasing morbidity risk 4
• Antibiotics are not routinely indicated after adequate surgical drainage in immunocompetent patients 1
• Antibiotic therapy is recommended in the following situations 1:
  • Presence of systemic signs of infection or sepsis
  • Immunocompromised patients
  • Incomplete source control
  • Significant surrounding cellulitis
• When indicated, empiric broad-spectrum antibiotic therapy should cover Gram-positive, Gram-negative, and anaerobic bacteria 1

Follow-up and Recurrence Prevention

• Close follow-up is essential to monitor for recurrence or fistula development 2
• The recurrence rate after drainage can be as high as 44%, with risk factors including 1:
  • Inadequate drainage
  • Loculations
  • Horseshoe-type abscess
  • Delayed time from disease onset to incision
• Evidence shows that fistula surgery with abscess drainage significantly reduces recurrence or persistence of abscess/fistula, or the need for repeat surgery 3
• For high perianal abscesses, incision and seton drainage has been shown to improve cure rates and reduce recurrence compared to incision and drainage alone 5

Special Considerations

• In pediatric patients, particularly infants, non-surgical management may be considered as an initial approach, as some cases may resolve spontaneously 6, 7
• In patients with Crohn's disease, MRI is considered the gold standard imaging technique for perianal fistulizing disease 1