What are the surgical treatment options for perianal fistulas?

Surgical Treatment Options for Perianal Fistulas

The optimal surgical approach for perianal fistulas depends primarily on fistula classification (simple vs. complex) and the presence of rectal inflammation, with fistulotomy recommended for simple fistulas and sphincter-preserving techniques for complex fistulas. 1

Classification of Perianal Fistulas

Perianal fistulas are classified into two main categories:

1. Simple fistulas:

   • Low fistulas (located in lower third of external anal sphincter)
   • Superficial, intersphincteric, or low transsphincteric
   • Single external opening
   • No evidence of rectal inflammation/proctitis
   • No associated complications

2. Complex fistulas:

   • High fistulas (upper two-thirds of external sphincter)
   • Multiple external openings
   • Associated with rectal inflammation/proctitis
   • Presence of complications (abscess, stricture, rectovaginal involvement)

Surgical Treatment Algorithm

For Simple Fistulas:

1. Fistulotomy:
   • First-line surgical treatment for simple fistulas 1
   • Involves laying open the fistula tract
   • High healing rates (reported up to 90%) with sustained results
   • Best performed in absence of proctitis 1
   • Lower risk of recurrence compared to sphincter-preserving procedures 1

For Complex Fistulas:

1. Seton Placement:

   • Initial step in management of complex fistulas 1
   • Non-cutting seton maintains drainage and prevents abscess formation
   • Can be used as bridge to definitive surgical treatment
   • Particularly important in patients with active rectal inflammation

2. Ligation of Intersphincteric Fistula Tract (LIFT):

   • Recommended for complex perianal fistulas 1
   • Involves ligation of fistula tract in intersphincteric plane
   • Success rates of 53% in Crohn's disease patients
   • Advantage: does not involve surgery on diseased mucosa
   • Best for single, non-branching fistulas with well-epithelialized tract

3. Advancement Flap (AF):

   • Alternative option for complex fistulas without proctitis 1
   • Involves raising mucosal flap to cover internal fistula opening
   • Success rates of 61-66% in Crohn's disease
   • Higher success when performed with concurrent anti-TNF therapy
   • Best for patients with single internal opening without proctitis/stenosis

4. Other Sphincter-Preserving Techniques:

   • Fistula plug insertion
   • Video-assisted ablation
   • Stem cell therapy (experimental)

5. Diversion/Proctectomy:

   • Reserved for severe, refractory cases
   • Temporary diversion (ileostomy/colostomy) rarely performed as most patients never have intestinal continuity restored
   • Proctectomy rates historically 10-18% for perianal Crohn's disease

Special Considerations

For Rectovaginal Fistulas:

• Fistulotomy should rarely be used due to sphincter injury risk 1
• Treatment options include:
  • Primary closure
  • Transanal advancement flap
  • Sleeve advancement flap
  • Transvaginal advancement flap
• Success rates range from 50-100% 1

Combined Medical-Surgical Approach:

• Current standard is multidisciplinary approach 1, 2
• Initial seton placement followed by medical therapy (preferably anti-TNF)
• After good response to anti-TNF, seton removal within 2-8 weeks
• In absence of proctitis, surgical closure should be considered 1

Pitfalls and Caveats

1. Proctitis Impact:

   • Presence of rectal inflammation significantly reduces success rates of surgical interventions
   • Fistulotomy should be avoided in patients with active proctitis 1

2. Recurrence Risk:

   • Clinical closure with medication alone achieves only 60% success rate
   • MRI-confirmed closure is rare (<10%) with medical therapy alone
   • Higher MRI-confirmed closure rates (up to 40%) with combined surgical-medical approach 1

3. Sphincter Function:

   • Fistulotomy in complex/high fistulas carries significant risk of incontinence
   • Sphincter-preserving techniques should be prioritized for complex fistulas

4. Cancer Risk:

   • Chronic perianal fistulas in Crohn's disease carry risk of malignant transformation
   • Long-standing fistulas should be monitored for development of squamous cell carcinoma, basal cell carcinoma, or adenocarcinoma 1

The management of perianal fistulas remains challenging despite advances in surgical techniques and medical therapy. Early surgical intervention with appropriate technique selection based on fistula classification offers the best chance for successful outcomes and improved quality of life.