What is the initial treatment for a patient with fistula in ano?

Initial Treatment for Fistula in Ano

Immediate surgical drainage is mandatory for all anorectal abscesses associated with fistula in ano and should be performed promptly to prevent further complications. 1

Diagnostic Approach

Before treatment, proper assessment is essential:

• Imaging: MRI is the gold standard for visualizing the extent of abscess and associated fistula tracts 1
• Examination Under Anesthesia (EUA): Should be performed by an experienced colorectal surgeon (up to 90% accuracy) 1
• Ultrasound: Preferred initial imaging to differentiate between hematoma and abscess 1

Treatment Algorithm

Step 1: Abscess Drainage

• All anorectal abscesses require immediate surgical drainage
• This is the primary and most urgent intervention to control infection and relieve symptoms

Step 2: Fistula Assessment and Classification

Based on the anatomical relationship to the sphincter complex:

• Simple fistulas: Intersphincteric or low transsphincteric fistulas
• Complex fistulas: High transsphincteric, suprasphincteric, or extrasphincteric fistulas

Step 3: Definitive Treatment Based on Classification

For Simple Fistulas:

• Intersphincteric fistulas: Fistulotomy is the procedure of choice (healing rate >95%) 2
• Low transsphincteric fistulas:
  • Fistulotomy for carefully selected patients
  • Sphincter-sparing techniques for others

For Complex Fistulas:

• Only sphincter-sparing techniques should be used 2
• Preferred options:
  • Ligation of Intersphincteric Fistulous Tract (LIFT)
  • Rectal advancement flaps
  • Both techniques have healing rates of 60-90% 2

Step 4: Seton Placement Considerations

• Setons promote wound drainage and prevent premature wound closure 1
• Long-term seton placement with medical therapy may be considered for complex fistulas, especially in Crohn's disease 1

Antibiotic Therapy

• For immunocompetent, non-critically ill patients with adequate source control: 4 days of antibiotics 1
• For immunocompromised or critically ill patients: up to 7 days based on clinical response 1
• Coverage should be guided by:
  • Location of abscess
  • Gram stain and culture results
  • Consideration for MRSA coverage (prevalence up to 35% in some locations) 1

Post-Drainage Management

• Remove packing within 24-48 hours
• Allow wound to heal by secondary intention
• Wound care:
  • Clean with warm water or saline 2-3 times daily
  • Sitz baths
  • Non-adherent absorbent dressing
  • Consider alginate or hydrofiber dressings for deeper wounds 1

Follow-Up Protocol

• First follow-up: Within 48-72 hours after packing removal
• Subsequent follow-ups: Every 1-2 weeks until complete healing
• More frequent assessment (every 1-2 days) for high-risk patients (inflammatory bowel disease, diabetes) 1
• Monitor for:
  • Recurrent abscess formation
  • Development of fistula (occurs in 30-40% of cases)
  • Delayed healing
  • Signs of infection 1

Special Considerations

• Crohn's Disease: Surgical outcomes are worse; recurrence is unpredictable 3
• Complex or High Fistulas: Consider newer techniques like fistula laser closure (FiLaC) or video-assisted anal fistula treatment (VAAFT) with reported healing rates of 65-90% 2
• Seton Management: If placed, maintain for 1-2 months until resolution of induration and suppuration 1

The treatment of fistula in ano requires careful assessment and appropriate surgical intervention based on the classification of the fistula. While simple fistulas can often be treated with fistulotomy, complex fistulas require sphincter-sparing techniques to minimize the risk of incontinence.