Urinary Fistula (Vesicovaginal Fistula)

A urinary fistula is an abnormal connection between the urinary tract and another organ or the skin, that allows urine to leak into an unintended space. In women the most common types are vesicovaginal fistula (between the bladder and vagina) and ureterovaginal fistula (between a ureter and the vagina). Fistulae to the bowel, uterus or skin also occur. The result is continuous or intermittent urinary leakage, which is deeply distressing and always warrants specialist assessment.

In the developed world the most common causes are pelvic surgery (particularly hysterectomy, but also caesarean section, pelvic floor and cancer surgery), pelvic radiotherapy, and injury from complex childbirth. Other causes include inflammatory bowel disease (Crohn’s disease), pelvic cancers, and pelvic infection. In the developing world, obstructed labour remains a major cause. Congenital fistulae are rare.

The hallmark symptom is continuous or intermittent urinary leakage from an abnormal site — typically watery discharge from the vagina between normal voiding, or leakage of urine into the bowel motion. Symptoms often start days or weeks after pelvic surgery. Other features include recurrent urinary tract infections, skin irritation, offensive-smelling discharge, and psychological distress. Recognising these symptoms early is important, as it allows earlier assessment and treatment.

Diagnosis starts with a detailed history and careful pelvic examination. Confirmatory investigations include a dye test (methylene blue or indigo carmine placed in the bladder to see if it appears in the vagina), cystoscopy, examination under anaesthetic, and imaging with CT urogram, pelvic MRI or intravenous urography to define the exact location, size and course of the fistula and to identify any associated ureteric injury.

A small proportion of simple, uncomplicated fistulae will heal with a period of continuous bladder drainage using a catheter for 4 to 6 weeks, particularly if identified very early. However, most established fistulae — especially those caused by surgery or radiation, or those with associated tissue damage — require surgical repair. Spontaneous closure becomes less likely with time, and prolonged conservative management can allow scarring that makes later surgery more difficult.

Surgical repair depends on the type, size, position and cause of the fistula. Vesicovaginal fistulae are typically repaired through a transvaginal or transabdominal (open, laparoscopic or robotic) approach, with careful closure of each layer and often interposition of well-vascularised tissue (such as a Martius flap or omentum) between the bladder and vagina. Ureterovaginal fistulae usually require ureteric reimplantation. Repair should be performed by a surgeon with specific expertise in fistula surgery. Honorary Associate Professor Jeremy Ockrim is one of the specialist fistula surgeons at University College London Hospital and has extensively published on his many years of fistula surgical experience.

In experienced hands, the success rate for first-attempt repair of a straightforward vesicovaginal fistula is around 90% or higher. Success rates fall for large, complex, recurrent or post-radiation fistulae, and for these cases specialist reconstructive expertise, careful timing of surgery, and use of tissue flaps and interposition grafts are important. Where a fistula is not repairable, urinary diversion offers effective symptom relief.

Any woman with continuous or unexplained urinary leakage, particularly after pelvic or gynaecological surgery, pelvic radiotherapy or difficult childbirth, should be referred to a reconstructive urologist promptly. Early specialist assessment gives the best chance of an accurate diagnosis, appropriate timing of surgery, and successful repair with a single operation. Delayed referral can worsen tissue damage and reduce success rates.