Recto-vaginal fistula

Rectovaginal fistula (RVF):

• RVFs are epithelial-lined tracts between the rectum and vagina - the majority of RVFs are located at or just above the dentate line. If a fistula is below the dentate line then this is an anovaginal fistula (i.e. not a true RVF)
• a low RVF is defined as being between the lower third of the rectum and the lower half of the vagina; a high RVF is between the middle third of the rectum and the posterior vaginal fornix. RVFs may vary greatly in size - the majority are less than 2 cm in diameter
• Causes:
  • most common cause is obstetric injury. Other causes in descending order of frequency include radiation injury, inflammatory bowel disease ((IBD), most often Crohn disease), operative trauma, infection, and neoplasm
• pathophysiology:
  • there are many causes of RVFs:
    • perineal lacerations during childbirth, particularly those due to episiotomy, predispose patients to RVFs.
      • perineal lacerations are more common in
        • primigravidas
        • in precipitous births
        • deliveries using forceps or vacuum extraction
        • also note that failure to recognise and correctly repair perineal lacerations (or secondary infection of perineal lacerations) increases the probability of developing a RVF
    • the development of an RVF may be predisposed by a prolonged labour. Pressure on the rectovaginal septum can produce necrosis and a consequent RVF
    • IBD (Crohn's and ulcerative colitis) have been associated with developments of RVF
    • radiation therapy used in pelvic malignancy may be complicated by development of a RVF
    • rectal or vaginal operations may cause a RVF
    • pelvic operations can be complicated by the development of a RVF
    • trauma
    • infection may cause a RVF
      • perirectal abscess/fistula and diverticulitis
      • rare causes include lymphogranuloma venereum (1), tuberculosis and Bartholin gland abscess
• Clinical features:
  • the usual presentation is that of flatus or, more rarely, stool through the vagina. Patients may also suffer recurrent episodes of cystitis or vaginitis
  • the patient may also complain of a foul-smelling vaginal discharge - in general, the passage of frank stool per vagina occurs only when the patient has diarrhoea
  • if there is associated anal sphincter damage then the patient may also complain of faecal incontinence
  • occasionally a patient with RVF is asymptomatic
• Management: refer for specialist advice
  • medical management options include:
  • if a fistula is secondary to trauma (including those secondary to obstetric trauma), caused by infection or complicated by secondary infection - in these situations then medical management including abscess drainage and antibiotic therapy may be employed. It may be decided to leave the RVF to heal for a 6-12 week period. During this period dietary modification and fibre supplements may substantially reduce symptoms. This treatment regime may result in complete healing of an RVF secondary to trauma. However if the RVF persists then surgical repair may be required.
  • if an RVF is due to another aetiology (e.g. IBD, neoplasm) then management will also be dictated by the aetiological process
  • surgical therapy (2): may be initial treatment or employed if failure of medical therapy.
    • obstetrical fistulas can be treated successfully by local approaches transanally or transvaginally - episioproctotomy may be considered if there is an associated sphincter defect
    • Crohn's related fistulas usually require proctectomy if the rectum is severely involved. Local repair can be considered in instances where the rectum is relatively healthy and local sepsis has been controlled
    • radiation-induced fistulas may be secondary to cancer recurrence, which must be excluded. If the patient is not a candidate for a radical resectional approach, faecal diversion alone should be performed

Reference:

1. Infect Dis Obstet Gynecol. 1999;7(4):199-201.
2. Tsang CB, Rothenberger DA: Rectovaginal fistulas. Therapeutic options. Surg Clin North Am 1997 Feb; 77(1): 95-114
3. Surg Clin North Am. 2002 Dec;82(6):1261-72.