What is the best treatment approach for a patient with recurrent perianal abscess?

Management of Recurrent Perianal Abscess

For patients with recurrent perianal abscess, the optimal treatment approach is surgical drainage combined with identification and management of the underlying fistula tract, as this significantly reduces recurrence rates and improves quality of life outcomes. 1

Initial Assessment and Diagnosis

• Imaging evaluation:

  • Contrast-enhanced pelvic MRI is the first-line imaging modality for assessment 1
  • Endoscopic anorectal ultrasound (EUS) is a good alternative if rectal stenosis is excluded 1
  • Examination under anesthesia (EUA) by an experienced surgeon remains the gold standard for definitive assessment 1, 2

• Concomitant evaluation:

  • Proctosigmoidoscopy to evaluate for rectal inflammation, which has prognostic and therapeutic relevance 1
  • Rule out underlying Crohn's disease, which significantly affects management approach 1

Surgical Management Algorithm

Step 1: Drainage and Fistula Assessment

1. Immediate management:

   • Surgical drainage of the abscess is mandatory 1, 2
   • The incision should be kept as close as possible to the anal verge to minimize potential fistula length 1
   • Complete and thorough drainage is essential, as inadequate drainage is a major risk factor for recurrence 1

2. Fistula identification:

   • A careful search for an underlying fistula should be performed during drainage 1, 3
   • Up to one-third of perianal abscesses are associated with a fistula-in-ano, which significantly increases recurrence risk if not addressed 1

Step 2: Fistula Management Based on Classification

1. For simple/low fistulas (not involving sphincter muscle):

   • Perform fistulotomy at the time of abscess drainage 1, 2
   • This approach significantly reduces recurrence rates (RR=0.13,95% CI 0.07-0.24) compared to drainage alone 4
   • A study in children showed zero recurrences when fistulotomy was performed at initial drainage versus high recurrence when drainage was performed alone 3

2. For complex fistulas (involving sphincter muscle):

   • Place a loose draining seton 1
   • Avoid fistulotomy to prevent incontinence 1
   • The timing of seton removal depends on subsequent therapy and resolution of inflammation 1, 2

Medical Management

1. Antibiotic therapy:

   • Indicated in specific circumstances:
     • Presence of sepsis or systemic infection
     • Surrounding soft tissue infection
     • Immunocompromised patients 1, 2
   • When indicated, use broad-spectrum antibiotics covering Gram-positive, Gram-negative, and anaerobic bacteria 2
   • A recent randomized controlled trial showed that routine antibiotic therapy after drainage does not reduce fistula formation or abscess recurrence in cryptogenic perianal abscesses 5

2. For patients with Crohn's disease:

   • Active luminal disease should be treated concurrently with surgical management 1
   • For complex fistulas in Crohn's disease, consider:
     • Infliximab as initial treatment of choice for complex fistulas 1
     • Azathioprine or 6-mercaptopurine as maintenance therapy 1
     • Antibiotics as adjunctive therapy 1

Follow-up and Monitoring

• First follow-up within 48-72 hours after drainage 2
• Subsequent follow-ups every 1-2 weeks until complete healing 2
• Monitor for:
  • Signs of recurrent abscess formation
  • Development of fistula
  • Delayed healing
  • Persistent infection 2

Special Considerations

• Risk factors for recurrence:

  • Inadequate initial drainage
  • Presence of loculations
  • Horseshoe-type abscess
  • Delayed time from disease onset to incision 1
  • Type of fistula (ischiorectal and transsphincteric fistulas have higher recurrence rates than superficial fistulas) 6

• Surgeon specialization:

  • Colorectal surgeons are more likely to identify fistulas during initial drainage compared to general surgeons (34% vs 10.9%) 7
  • However, a recent study found no significant difference in recurrence rates between patients treated by colorectal specialists versus general surgeons 7

Common Pitfalls to Avoid

1. Inadequate drainage: Ensure complete drainage of all loculations to prevent recurrence 1, 2

2. Failure to identify fistula: Always search for an underlying fistula during initial drainage 1, 3

3. Inappropriate fistula management: Do not perform fistulotomy for complex fistulas involving the sphincter muscle due to risk of incontinence 1

4. Unnecessary probing: Avoid excessive probing to search for non-obvious fistulas, as this may cause iatrogenic complications 1

5. Overuse of antibiotics: Do not routinely prescribe antibiotics after adequate drainage of uncomplicated abscesses 5