B1. Genital fistulas – pathomechanism, diagnosis and therapy

From greek.doctor

Fistulation between genitalia and the urinary tract, bowel, or skin are rare complications in gynaecology and obstetrics. The most common fistulas are:

  • Urogenital fistulas
    • Vesicovaginal fistula
    • Ureterovaginal fistula
    • Urethrovaginal fistula
    • Vesicouterine fistula
  • Enterogenital fistulas
    • Rectovaginal fistula
  • Vaginocutaneous fistulas

Fistulas are more common in the developing world due to inadequate pregnancy and perinatal care.

Urogenital fistulas are the most common type of genital fistula, with vesicovaginal fistula being the most common. Enterogenital fistulas are less frequent, but more frequently due to IBD.

Etiology

  • Pelvic surgery
    • Hysterectomy
    • C-section
    • Cancer surgery
    • Surgery for prolapse
  • Pelvic irradiation
  • Prolonged/obstructed labour (mostly in developing countries)
  • Cancer
  • Inflammatory bowel disease

In the developed world, surgery and irradiation are the most common causes. In the developing world, obstructed labour is the most common cause.

Clinical features

Urogenital fistulas present with continuous leakage of urine, causing urinary incontinence.

Enterogenital fistulas present with leakage of air and sometimes faeces from the vagina.

Diagnosis and evaluation

Thorough physical examination is important. Sometimes the opening to the fistula may be visible, but not always. We may also see leakage of urine or faeces. If an opening is found, we may attempt to probe it with a thin probe to determine whether it’s a fistula or not.

A dye test is useful to evaluate for fistula. If urogenital fistula is suspected, a dyed sterile fluid (methylene blue or indigo carmine) is instilled into the bladder through a bladder catheter. A tampon is inserted into the vagina and later examined for dye. To distinguish between vesicovaginal and ureterovaginal fistulas, we can use two separate dyes of different colours, one administered into the bladder and the other orally or IV. The colour of the dye on the tampon will tell you whether the dye came from the bladder or the ureter.

If enterogenital fistula is suspected, dye can be instilled into the anus and a tampon can be inserted into the vagina and later examined for dye.

Endoscopy, either cystoscopy, urethrascopy, anoscopy, or rectoscopy, may be used to further look for or examine the fistula.

Imaging, including ultrasound and CT/MRI (with contrast) may also assist in the diagnosis and evaluation.

Treatment

The primary treatment of urogenital fistulas is bladder catheterisation. If discovered early, the patient should be catheterised for 4 – 12 weeks to allow the fistula to heal by itself. However, this is only successful for 10% of patients.

The second choice is surgical repair. One such surgical procedure is the Latzko procedure. The patient should be catheterised for 1 – 2 weeks afterward to let the fistula heal.

For ureteric fistulas, percutaneous stenting the affected ureter for some time (1 – 3 months) may allow the ureterovaginal fistula to heal. Surgical repair is the second option.

Rectovaginal fistula may be treated conservatively or surgically. Conservative treatment includes nil per os with parenteral nutrition or only liquid foods for some time to allow the fistula to heal. Surgery may involve forming a temporary enterostomy.