What is the optimal treatment for an ileosigmoid fistula in Crohn's disease (CD)?

Optimal Treatment for Ileosigmoid Fistula in Crohn's Disease

The optimal treatment for an ileosigmoid fistula in Crohn's disease is ileocecectomy and sigmoid colectomy (option C) when there is active disease involvement of both the ileum and sigmoid colon. 1

Assessment of Fistula and Disease Involvement

Before determining the specific surgical approach, careful evaluation is necessary:

• Imaging studies: Cross-sectional imaging (MR enterography or CT enterography) to assess the extent of disease and fistula characteristics 1
• Endoscopy: To determine if there is active Crohn's disease in the sigmoid colon 2
• Disease pattern: Determine if the fistula originates from active Crohn's disease in the terminal ileum with or without sigmoid involvement 3, 4

Surgical Decision Algorithm

The surgical approach should be based on the pattern of disease involvement:

1. Terminal ileum disease with fistula to normal sigmoid (Group I):

   • Ileocolic resection with simple closure of the sigmoid defect 3, 5
   • This approach is appropriate when the sigmoid shows only serosal inflammation without active Crohn's disease

2. Terminal ileum disease with active sigmoid involvement (Group II):

   • Ileocecectomy and sigmoid colectomy (double resection) 3, 2
   • This is the preferred approach when both ends of the fistula show active disease

3. Diffuse ileocolitis with fistula (Group III):

   • More extensive surgery (subtotal colectomy with ileostomy) may be required 3

4. Left-sided colonic disease with fistula to normal ileum (Group IV):

   • Double resection with removal of the diseased sigmoid and closure of the ileal defect 3

Key Considerations for Surgical Management

• Sigmoid assessment: Intraoperative assessment of the sigmoid colon is crucial - surgeon's evaluation correlates well with pathologic findings when aided by preoperative endoscopy results 2

• Indications for sigmoid resection rather than repair:

  • Significant purulence or inflammation
  • Large fistula defect
  • Defect on the mesenteric border of sigmoid
  • Active Crohn's disease in the sigmoid 2, 6

• Temporary diversion considerations:

  • Stoma creation may be necessary in cases with:
    • Preoperative steroid use ≥20 mg prednisone
    • Preoperative albumin ≤3.5 g/dL
    • Need for additional small bowel procedures
    • Extensive inflammation 6

Surgical Outcomes

• Mortality is negligible with proper surgical management 6
• Overall morbidity is approximately 37%, with anastomotic leak rate around 4% 6
• Both sigmoid resection and primary repair have comparable morbidity when appropriately selected 6

Common Pitfalls to Avoid

• Misdiagnosis: Preoperative detection rate of ileosigmoid fistulas is only about 71% across all modalities 4, with individual sensitivities of colonoscopy (35%), CT scan (41%), and fluoroscopy (53%) 6

• Inappropriate sigmoid management: Assuming all sigmoid involvement requires resection - approximately 47% of patients have granulomatous involvement at only one end of the fistula 3

• Unnecessary stoma creation: The presence of a fistula alone is not an absolute indication for diversion 5

• Failure to address concomitant disease: Up to 38% of patients may require additional procedures for other Crohn's manifestations (ileovesical fistulas, enterocutaneous fistulas, synchronous small bowel disease) 6

In conclusion, while treatment must be tailored to the specific disease pattern, ileocecectomy and sigmoid colectomy represents the optimal approach for most symptomatic ileosigmoid fistulas in Crohn's disease with active involvement of both bowel segments.