Management of Anal Fistula
For simple intersphincteric anal fistulas, perform fistulotomy as the procedure of choice with >95% healing rates; for complex fistulas, use sphincter-saving techniques such as LIFT or advancement flaps achieving 60-90% healing rates, and always place loose setons for drainage before definitive surgery when concomitant proctitis is present. 1, 2
Initial Assessment and Classification
The first critical step is distinguishing simple from complex fistulas, as this determines your entire treatment algorithm 3, 2:
- Simple fistulas include low intersphincteric and low transsphincteric tracts with a single external opening, no active proctitis, and minimal sphincter involvement 3, 2
- Complex fistulas involve high transsphincteric, suprasphincteric, or extrasphincteric tracts, multiple openings, recurrent disease, or association with Crohn's disease, radiation, or malignancy 3, 2
Key diagnostic maneuver: Inspect the perianal area to identify the external opening, then perform anoscopy to visualize the internal opening 3. For complex cases, consider MRI or endoanal ultrasound to map the tract anatomy before surgery 4.
Treatment Algorithm for Simple Fistulas
Intersphincteric Fistulas
Perform fistulotomy immediately - this remains the gold standard with healing rates exceeding 95% and minimal risk of incontinence 1, 2. The procedure involves laying open the entire fistulous tract from internal to external opening 2.
Low Transsphincteric Fistulas
Patient selection is crucial here 2:
- In patients with normal continence and minimal sphincter involvement: Fistulotomy is safe and effective with >95% healing 2
- In patients with any continence concerns or significant sphincter involvement: Choose sphincter-saving techniques immediately rather than risk incontinence 2
Treatment Algorithm for Complex Fistulas
Never perform simple fistulotomy for complex fistulas - the sphincter damage will cause incontinence 2. Your options, in order of preference based on outcomes:
First-Line Sphincter-Saving Techniques
LIFT (Ligation of Intersphincteric Fistulous Tract): Achieves 60-90% healing rates with excellent continence preservation 2. This involves identifying and ligating the tract in the intersphincteric space 2.
Rectal Advancement Flap: Also achieves 60-90% healing rates 2. This technique covers the internal opening with healthy rectal mucosa 2.
Loose Seton Placement: Always place setons for drainage before definitive surgery when concomitant proctitis is present 1. Setons allow drainage while inflammation resolves, preventing abscess formation 1.
Emerging Techniques with Promising Results
- FiLaC (Fistula Laser Closure): Reports 65-90% healing rates with minimal sphincter damage 2
- VAAFT (Video-Assisted Anal Fistula Treatment): Achieves 65-90% healing rates with direct visualization 2
- TROPIS (Transanal Opening of Intersphincteric Space): Currently under evaluation but shows promise 2
Less Effective Options
- Fibrin glue injection: Lower success rates, consider only when other options are contraindicated 3
- Bioprosthetic plugs: Variable results, not first-line 3
Critical Pitfalls to Avoid
Do not perform fistulectomy with primary sphincter division in complex fistulas - this causes unacceptable rates of incontinence 2. The goal is always to obliterate the tract while preserving sphincter function 3.
Do not attempt definitive surgery in the presence of active infection or proctitis - place drainage setons first and allow inflammation to resolve 1.
Beware of recurrent fistulas - these often indicate missed secondary tracts or underlying Crohn's disease requiring medical optimization before repeat surgery 5, 2.
Special Considerations
For Crohn's-related fistulas: Medical optimization with biologics is essential before surgical intervention, and seton drainage is often the safest long-term approach 5.
Recurrence rates vary significantly: simple fistulas have <5% recurrence with fistulotomy, while complex fistulas have 10-40% recurrence depending on technique used 2. This underscores why technique selection matters critically.
Surgeon experience is paramount - familiarity with multiple sphincter-saving techniques is essential because no single technique treats all fistulas successfully 2. When facing a complex case beyond your expertise, refer to a colorectal surgeon 2.