What is a fistula?

What is a Fistula?

A fistula is an abnormal connection or tract between two epithelial surfaces, such as between two hollow organs, or between an organ and the skin. 1

Types of Fistulas

Fistulas are typically named according to the two structures they connect:

1. Enterocutaneous fistula: Connection between the intestine and skin 1, 2
2. Enteroenteric fistula: Connection between two segments of bowel 3
3. Enterovesical fistula: Connection between intestine and bladder 3
4. Enterovaginal fistula: Connection between intestine and vagina 3
5. Arteriovenous fistula: Connection between an artery and vein (often created intentionally for hemodialysis access) 3
6. Perianal fistula: Connection between the anal canal and perianal skin 4
7. Coronary artery fistula: Abnormal connection of a coronary artery with a heart chamber or blood vessel 5

Causes of Fistulas

Fistulas can develop due to various causes:

• Surgical complications: Most common cause in developed countries 1
• Inflammatory bowel disease: Particularly Crohn's disease 3
• Infection: Leading to abscess formation that eventually creates a fistulous tract 4
• Malignancy: Tumors can erode through tissues creating abnormal connections 1
• Radiation therapy: Tissue damage from radiation can lead to fistula formation 1
• Trauma: Including foreign body penetration 1
• Congenital abnormalities: Present from birth 5

Clinical Presentation

Symptoms depend on the location and type of fistula:

• Pain: Often localized to the fistula site
• Drainage: Abnormal discharge from the fistula opening
• Infection: Recurrent infections are common
• Systemic symptoms: Fever, malaise, weight loss in extensive cases 1
• Specific symptoms: Based on organs involved (e.g., fecal material from skin in enterocutaneous fistulas, painful defecation in anal fistulas) 4, 2

Diagnosis

Diagnosis typically involves:

• Clinical examination: Visual inspection and palpation of suspected fistula sites
• Imaging studies:
  • CT scan: Often first-line imaging, especially with contrast 1
  • MRI: Particularly useful for perianal and complex fistulas 3
  • Ultrasound: Can identify and characterize certain fistulas 3
• Fistulography: Direct contrast injection into the fistula tract
• Endoscopy: To visualize internal openings and underlying disease 1

Management

Management depends on the type, location, and underlying cause:

• Non-surgical approaches:

  • Control of sepsis and infection 6, 2
  • Nutritional support 6
  • Fluid and electrolyte management 6, 2
  • Wound care and effluent control 2
  • Medical therapy for underlying conditions (e.g., Crohn's disease) 3

• Surgical approaches:

  • Fistulotomy: Opening the fistula tract (for simple fistulas) 4
  • Fistulectomy: Removal of the entire fistula tract 4
  • Seton placement: Drainage of complex fistulas 4
  • Resection and anastomosis: For intestinal fistulas 6
  • Creation of arteriovenous fistulas: Intentionally created for hemodialysis access 3, 7

Special Considerations

• Arteriovenous fistulas for hemodialysis: These are intentionally created connections between an artery and vein, typically in the arm, to provide vascular access for hemodialysis. They are the preferred access method due to lower complication rates and better long-term patency 3, 7.

• Complex fistulas: May require specialized approaches and multidisciplinary management 3, 6, 2.

• Monitoring and maintenance: Particularly important for hemodialysis fistulas to ensure continued function 3.

Complications

• Sepsis: Particularly with enterocutaneous fistulas 6, 2
• Malnutrition: Due to nutrient losses or reduced intake 6
• Fluid and electrolyte imbalances: Especially with high-output fistulas 6
• Skin breakdown: Around external openings 2
• Organ dysfunction: Based on involved structures

Understanding the type, location, and underlying cause of a fistula is essential for proper management and treatment planning. A multidisciplinary approach involving specialists relevant to the affected organs is often necessary for optimal outcomes.