Urinary Fistula

Overview

A urinary fistula is an abnormal passage connecting the urinary tract to another organ or the skin surface. This connection allows urine to leak from its normal pathway into another body cavity, or permits contents from other organs (such as stool or air from the bowel) to enter the bladder. Fistulas are named according to the structures they connect—for example, a vesicovaginal fistula connects the bladder to the vagina.

Urinary fistulas cause significant physical and psychological distress. In developing countries, obstetric fistulas from prolonged labor affect approximately 2 million women, often leading to devastating social consequences. In developed countries, surgical injury during pelvic procedures is the primary cause. The good news is that surgical repair achieves success rates of 85-95% with experienced surgeons.

Types

Vesicovaginal fistula (VVF) is the most common type in women, creating a connection between the bladder and vagina that causes continuous urine leakage. This type has profoundly different causes depending on geography—obstetric trauma predominates in developing nations while surgical injury is more common in developed countries.

Urethrovaginal fistula connects the urethra to the vagina. These typically result from urethral surgery, trauma, or complicated childbirth. Symptoms may mimic stress urinary incontinence depending on the fistula’s location along the urethra.

Vesicouterine fistula is a rare connection between the bladder and uterus, most often occurring after cesarean section. A distinctive symptom called menouria—urine appearing during menstruation—may occur.

Ureterovaginal fistula involves a ureter (the tube from kidney to bladder) connecting abnormally to the vagina. This often follows pelvic surgery and causes continuous leakage, though the patient may still void normally since urine from one kidney continues draining through the bladder.

Colovesical fistula connects the colon to the bladder, producing the classic symptoms of pneumaturia (passing air with urination) and fecaluria (stool particles in urine). Diverticulitis is the most common cause, followed by colon cancer and Crohn’s disease. These occur more frequently in men because the uterus provides a protective barrier in women.

Enterovesical fistula connects the small bowel to the bladder, causing similar symptoms to colovesical fistula.

Vesicocutaneous fistula creates a passage between the bladder and skin surface, allowing urine to drain externally. This usually results from surgery or trauma.

Symptoms

The symptoms of urinary fistula depend entirely on which structures are connected.

Women with vesicovaginal fistula experience continuous urine leakage from the vagina—day and night, regardless of activity or position. This distinguishes VVF from stress incontinence, where leakage occurs only with physical exertion. The constant moisture leads to vaginal irritation, skin breakdown, and a persistent urine odor. Recurrent urinary tract infections commonly develop. The condition often causes profound social isolation and psychological distress.

Colovesical fistula produces pathognomonic symptoms that strongly suggest the diagnosis. Pneumaturia—the passage of air bubbles during urination—is highly specific for a bowel-bladder connection. Fecaluria (visible stool in urine) and persistently foul-smelling urine are additional hallmarks. Patients typically experience frequent urination, urgency, and recurrent polymicrobial urinary tract infections.

General warning signs that should prompt investigation for any fistula type include recurrent or persistent urinary infections that fail to resolve with standard treatment, unusual vaginal or urethral discharge, and unexplained changes in voiding patterns.

Causes

Obstetric injury remains the leading cause of vesicovaginal fistula worldwide. During prolonged obstructed labor, the fetal head compresses bladder and vaginal tissues against the maternal pelvis for extended periods. This sustained pressure cuts off blood supply, causing tissue death (necrosis) and subsequent fistula formation. These injuries are largely preventable with access to skilled birth attendants and emergency cesarean section when needed.

Pelvic surgery is the primary cause of urinary fistulas in developed countries. Hysterectomy accounts for most surgical fistulas, occurring in less than 1% of procedures but with higher risk when performed for cancer, after previous radiation therapy, or when significant scarring exists from prior surgeries. Other contributing procedures include cesarean section, pelvic organ prolapse repair, and incontinence surgery. Ureteral injury during surgery may also create ureterovaginal fistulas.

Radiation therapy to the pelvis for cervical, rectal, or prostate cancer damages blood vessel walls, progressively compromising tissue nutrition. Radiation fistulas may develop months to years after treatment as tissues slowly break down. These are among the most challenging fistulas to repair because surrounding tissues remain compromised.

Cancer can cause fistulas through direct invasion of tissues. Cervical cancer is the most common malignancy causing vesicovaginal fistula, while bladder cancer and colorectal cancer may erode into adjacent structures.

Diverticulitis is the most common cause of colovesical fistula. When a colonic diverticulum becomes inflamed, it may adhere to and eventually erode through the bladder wall. Crohn’s disease can cause various fistula types as part of its characteristic fistulizing behavior.

Trauma from pelvic fractures, penetrating injuries, or long-term catheter pressure may also create fistulas.

Diagnosis

Clinical suspicion based on symptoms is the first step in diagnosis. Continuous vaginal urine leakage strongly suggests vesicovaginal fistula, while pneumaturia combined with fecaluria points to colovesical fistula. A history of pelvic surgery, radiation therapy, prolonged labor, or diverticular disease increases suspicion.

For suspected vesicovaginal fistula, a dye test provides simple confirmation. The bladder is filled with colored dye (methylene blue or indigo carmine) while a tampon is placed in the vagina. If the tampon stains blue, a bladder-vagina connection exists. This test also helps distinguish VVF from ureterovaginal fistula, where dye would not appear (since urine leaks directly from the ureter).

Cystoscopy allows direct visualization of the fistula opening on the bladder wall, assessment of its size and location, and evaluation for underlying malignancy. For vesicointestinal fistulas, cystoscopy often reveals inflammation (bullous edema) even when the fistula opening itself is not visible.

Imaging studies define fistula anatomy for surgical planning. CT urography maps the entire urinary tract and may demonstrate the fistula tract. MRI provides excellent soft tissue detail and is particularly valuable for complex or recurrent fistulas. For colovesical fistulas, CT may show air within the bladder and surrounding inflammatory changes. Colonoscopy evaluates the bowel for underlying disease such as diverticulosis, cancer, or Crohn’s disease.

Treatment

Treatment principles include addressing any underlying disease (such as cancer or active inflammation), optimizing tissue health before repair, allowing acute inflammation to settle when possible, and surgical repair for definitive correction.

Conservative management is occasionally successful for very small vesicovaginal fistulas (less than 5mm) that are diagnosed early. Continuous bladder drainage via catheter for 2-4 weeks keeps the bladder empty, allowing spontaneous healing. However, success rates are low for larger fistulas, and most patients ultimately require surgery.

Vesicovaginal fistula repair is performed through vaginal, abdominal, or minimally invasive approaches depending on fistula characteristics. The vaginal approach suits most straightforward fistulas and offers faster recovery. Abdominal or laparoscopic/robotic approaches are preferred for complex cases, recurrent fistulas, or those near the ureteral openings. Traditional teaching advised waiting 3-6 months after injury before repair, but modern practice supports earlier surgery once active infection and inflammation have resolved. Radiation-induced fistulas require longer delays because tissue quality remains compromised. First-repair success rates reach 85-95%.

Colovesical fistula repair requires treatment of the underlying bowel disease. For diverticulitis, initial antibiotic therapy is followed by surgical resection of the affected colon segment along with repair of the bladder defect. This may be performed as a one-stage or two-stage procedure, sometimes requiring temporary colostomy. For Crohn’s disease, medical optimization with immunomodulators often precedes surgery. Cancer requires appropriate oncological management.

Obstetric fistula repair demands specialized surgical expertise because extensive scarring and tissue loss make these cases technically challenging. Dedicated fistula centers in endemic regions achieve high success rates, though some patients require multiple surgeries. Prevention through access to skilled obstetric care remains paramount.

When to See a Doctor

Seek immediate medical evaluation if you experience continuous urine leakage from the vagina, as this suggests vesicovaginal fistula requiring surgical repair. Passing air or stool particles in urine indicates bowel-bladder fistula and warrants urgent assessment to identify the underlying cause.

Consult your doctor promptly for recurrent urinary tract infections that fail to respond to standard treatment, unexplained vaginal discharge with urine odor, or any persistent changes in urinary patterns following pelvic surgery or radiation therapy. Early diagnosis allows timely treatment and prevents complications.

While awaiting definitive treatment, protect skin with barrier creams, use absorbent products, maintain meticulous hygiene, and treat urinary tract infections promptly. Seek support groups if available—the psychological impact of living with a fistula is significant, and connecting with others facing similar challenges provides valuable emotional support.

After successful fistula repair, follow your surgeon’s activity restrictions carefully, avoid heavy lifting and straining during healing, and report any recurrence of leakage immediately. Most women achieve complete continence after repair and resume normal activities within several weeks.