The approach varies depending on the fistula’s location, complexity, and underlying cause, with a focus on anal fistulas as the most common:

1. Before Surgery Evaluation:
   
   • Diagnosis:
     
     • Anal fistula: Digital rectal exam, proctoscopy, or fistulography (contrast injection to map the tract); MRI or endoanal ultrasound for complex cases.
     • Enterocutaneous/enterovesical: CT scan, fistulography, or cystoscopy to identify the tract and associated conditions (e.g., Crohn’s disease).
     • Blood tests assess infection (e.g., WBC, CRP), nutrition (e.g., albumin), and comorbidities.
   • Bowel preparation (enema) clears the rectum for anal fistula surgery.
   • Antibiotics (e.g., metronidazole, ciprofloxacin) are started for active infection or in enterocutaneous cases.
   • Nutritional optimization (e.g., parenteral nutrition) is critical for enterocutaneous fistulas to promote healing.
2. Surgical Techniques:
   
   • Anal Fistula Surgery:
     
     • Performed under general or spinal anesthesia, lasting 30–90 minutes.
     • Fistulotomy:
       
       • For simple, low fistulas (not crossing much of the sphincter).
       • The fistula tract is opened along its length, allowing it to heal from the inside out.
       • The wound is left open with gauze packing; heals in 4–6 weeks.
     • Seton Placement:
       
       • For complex or high fistulas (crossing >30% of the sphincter).
       • A non-absorbable suture (seton) is threaded through the tract to keep it open, drain infection, and promote fibrosis.
       • Left in place for 6–12 weeks; a second-stage fistulotomy or other procedure may follow.
     • Advancement Flap:
       
       • For complex fistulas to preserve continence.
       • The internal opening is closed with a flap of rectal mucosa advanced over the defect.
     • LIFT Procedure (Ligation of Intersphincteric Fistula Tract):
       
       • The tract is accessed in the intersphincteric space, ligated, and divided, sparing the sphincter.
       • Suitable for transsphincteric fistulas.
   • Enterocutaneous Fistula Surgery:
     
     • Performed under general anesthesia, lasting 2–4 hours.
     • The fistula tract is excised, and the bowel is repaired (e.g., resection and anastomosis).
     • A stoma (e.g., ileostomy) may be created to divert stool and promote healing.
     • Often delayed 3–6 months after initial drainage and nutritional optimization.
   • Enterovesical Fistula Surgery:
     
     • Involves resection of the involved bowel segment, bladder repair, and omental interposition to prevent recurrence.
     • A Foley catheter is left in place for 7–14 days to rest the bladder.
   • Arteriovenous Fistula Repair:
     
     • Open surgery or endovascular embolization to disconnect the abnormal connection, performed by a vascular surgeon.
3. After Surgery:
   
   • Anal fistula: Patients are monitored for a few hours (outpatient) or 1–2 days (complex cases).
   • Enterocutaneous/enterovesical: Hospital stay of 5–10 days; parenteral nutrition may continue.
   • Pain is managed with analgesics (e.g., paracetamol, ibuprofen).
   • Antibiotics are continued for 5–7 days if infection was present.
   • Sitz baths (warm water soaks) 2–3 times daily promote healing in anal fistula cases.