Urinary fistula

Urinary fistulas are abnormal connections between the urinary tract and another organ or body surface.

The pathophysiology of urinary fistulas typically involves tissue damage and necrosis, subsequently leading fistula formation. This damage can arise from a variety of causes, including trauma, surgery, or infection. Obstetric fistulas often occur due to prolonged obstructed labor, leading to tissue ischemia and necrosis and the formation of a fistula between the urinary and genital tracts.

The incidence of bladder injury associated with gynecologic surgery is estimated at 3.2-4.8%. The prevalence of vesicovaginal fistula is estimated at 1 in 1,000 after hysterectomy and 1 in 1,000 deliveries.

Risk factors for urinary fistulas include previous pelvic surgeries, radiation therapy, pelvic malignancies, and vaginal foreign bodies. For obstetric fistulas, risk factors include prolonged obstructed labor, teenage pregnancy, and home delivery without skilled birth attendants.

The clinical course of urinary fistulas can vary widely depending on the location and size of the fistula. Common symptoms include urine leakage, urinary incontinence, recurrent UTIs, discomfort, and skin irritation or breakdown in the area where the urine is leaking. In vesicouterine fistulas, patients may present with hematuria, vaginal leakage of urine, and urethral passage of lochia.

The prognosis of urinary fistulas is largely dependent on the cause, location, and size of the fistula. Simple obstetric fistulas with the following characteristics generally have a good prognosis: single fistula < 4 cm, vesicovaginal fistula, closing mechanism not involved, no circumferential defect, minimal tissue loss, ureters not involved, first attempt to repair. Complex obstetric fistulas with the following characteristics have an uncertain prognosis: fistula > 4 cm, multiple fistula, rectovaginal mixed fistula, cervical fistula, closing mechanism involved, scarring, circumferential defect, extensive tissue loss, intravaginal ureters, failed previous repair, radiation fistula.