What are the types of vesicovaginal (VVF) fistulas?

Types of Vesicovaginal Fistulas

Vesicovaginal fistulas (VVFs) are classified based on their anatomical location, complexity, and etiology, with the main types being simple and complex fistulas, which have significant implications for treatment approach and outcomes.

Anatomical Classification

• VVFs can be classified as high or low fistulas based on their anatomical location relative to the urinary tract 1:

  • High fistulas: Communication between the vagina and bladder above the sphincter complex 1
  • Low fistulas: Communication between the vagina and lower urinary tract involving the sphincter complex 1

• Using the Parks classification system (originally developed for perianal fistulas but applicable to VVFs), fistulas can be categorized as 1:

  • Superficial (low): Involve superficial tissue layers
  • Intersphincteric (low or high): Pass through the internal sphincter
  • Transsphincteric (low or high): Cross both internal and external sphincters
  • Suprasphincteric (high): Pass above the sphincter complex
  • Extrasphincteric (high): Bypass the sphincter complex entirely

Clinical Classification

• VVFs are commonly classified as either simple or complex based on clinical characteristics 1:

• Simple VVFs:

  • Single, small fistulous tract (<0.7 cm) 2
  • Low anatomical position (superficial or low intersphincteric)
  • Single external opening
  • No associated pain or fluctuation suggesting abscess
  • No evidence of associated stricture
  • No active inflammation in surrounding tissues 1

• Complex VVFs:

  • High anatomical position (high intersphincteric, transsphincteric, extrasphincteric, or suprasphincteric)
  • Multiple external openings
  • Associated with pain or fluctuation suggesting abscess
  • Associated with strictures
  • Associated with active inflammation in surrounding tissues
  • Recurrent fistulas after previous repair attempts 3
  • Radiation-induced fistulas 4

Etiological Classification

• Obstetric VVFs:

  • Most common in developing countries
  • Result from prolonged obstructed labor causing tissue necrosis 5, 6
  • Often larger and more complex

• Iatrogenic VVFs:

  • Most common in developed countries
  • Result from surgical complications (particularly hysterectomy)
  • Occur in approximately 1 in 1000 post-hysterectomy patients 5
  • Usually smaller and more amenable to repair

• Radiation-induced VVFs:

  • Result from tissue damage following radiation therapy for pelvic malignancies
  • Often complex and difficult to repair
  • May require more specialized approaches 4

• Malignancy-associated VVFs:

  • Direct invasion of bladder and vagina by pelvic malignancies
  • Often require more complex management 7

Imaging Classification

• Based on imaging characteristics, VVFs can be classified according to:
  • Size (small <0.5 cm, medium 0.5-2.5 cm, large >2.5 cm) 6, 3
  • Presence of single or multiple tracts 1
  • Involvement of surrounding structures 1
  • Presence of associated abscesses or inflammation 1

Management Implications

• Treatment approach varies significantly based on fistula type:

  • Simple fistulas may be amenable to endoscopic fulguration with success rates up to 80% 2
  • Complex fistulas typically require surgical repair with success rates of 70-100% in non-radiated patients 4
  • Radiation-induced fistulas have lower success rates (40-100%) and may require urinary diversion 4

• The transvaginal approach is generally preferred for most VVFs, while the abdominal approach may be necessary for complex or recurrent cases 3

• Timing of repair is crucial, with most guidelines recommending waiting 4-6 weeks after fistula development before attempting surgical repair 4