Vesicovaginal Fistula

Etiology

The etiology of this condition varies and can be categorized into congenital or acquired. Acquired vesicovaginal fistula can be further divided into obstetric surgical, malignant, radiation, and miscellaneous categories. Congenital vesicovaginal fistula is very rare and typically associated with other urogenital malformations. Vesicovaginal fistula occurs most commonly after obstetrical and gynecological injury. In the developed world, the most common cause of vesicovaginal fistula is gynecological surgery. In North America, bladder injury during a hysterectomy is the most common cause. In developing countries, obstructed labor and the resulting pressure necrosis are the most common causes of vesicovaginal fistulas. Poor socioeconomic status, malnourishment, low literacy rate, early marriage and childbearing, and inadequate obstetrical care are important risk factors for developing a vesicovaginal fistula in the developing world.[1] Miscellaneous acquired causes of this condition include retroperitoneal, vascular, or pelvic surgery, urologic or gynecologic instrumentation, infectious and inflammatory diseases, sexual trauma, vaginal laser procedures, external violence, and vaginal foreign bodies.[3]

Epidemiology

The frequency of vesicovaginal fistula is rare in the developed world. In the developing and underdeveloped parts of the world, it has a much higher prevalence.[4] It has been reported that at least 3 million women in poor underdeveloped countries suffer from unrepaired vesicovaginal fistula; of these 3 million, an estimated 2 million women live in sub-Saharan Africa and South Asia; estimates suggest that 30,000 to 130,000 new cases develop each year due to obstructed labor in Africa alone.[5] However, the true incidence and prevalence in females worldwide are difficult to pronounce, given the significant stigmatization in many populations. Hysterectomy is the most common gynecological surgery resulting in vesicovaginal fistula formation, accounting for 80% of the annual incidence in developed countries. The rate of vesicovaginal fistula formation varies with the surgical approach. The highest is with laparoscopic procedures (2.2 in 1000), followed by transabdominal (1 in 1000), and the lowest is with the transvaginal approach (0.2 in 1000).[6]

History and Physical

The classic clinical presentation of a patient with a vesicovaginal fistula is continuous urinary incontinence after recent pelvic surgery. The severity of symptomology and timing of presentation is variable. Postoperative patients with a vesicovaginal fistula are usually easily diagnosed by the complaint of urine leaking through the vagina 7 to 12 days after gynecological or pelvic surgery. The timing of symptomology is likely related to tissue necrosis following obstructed prolonged labor or tissue strangulated by sutures placed during pelvic surgery. 

The diagnosis can be confirmed by completing a tampon dye test. This test involves inserting a regular tampon or gauze in the vagina, then back-filling the bladder with dilute methylene blue and having the patient ambulate—this can be performed shortly after filling the bladder, and a prolonged period of ambulation is not required as long as the bladder was sufficiently full with 200 to 300 mL of fluid. It is preferable to place the gauze or tampon before back-filling the bladder to avoid contaminating the gauze with dye during insertion. The tampon or gauze is then removed and inspected; if there is blue dye noted on the gauze near the apex, a vesicovaginal fistula is confirmed. If the dye is only noted on the distal tampon, this may represent spillage of the dye during filling or other forms of urinary incontinence.[7]

The diagnosis of a vesicovaginal fistula can be made in an outpatient clinical setting. A thorough evaluation of the size, number, and location of the fistula is important before curative surgery is undertaken. Physical examination, including a lighted speculum exam, of the fistula and surrounding structures, is extremely important to evaluate for acute inflammation, infection, edema, necrosis, or other bladder or vaginal pathology. Surgical correction of the defect should be postponed for up to 2 to 3 months if needed to allow for recovery and optimal tissue health. However, if there is no evidence of inflammation, and the tissue appears healthy, the surgical correction does not need to be postponed.[8] Office cystoscopy and contrast studies, such as computed tomography (CT) urogram, are generally used to aid in the diagnosis of additional injuries (such as a concomitant ureteral injury or fistula) and for surgical planning.

Evaluation

Considering the suspicious genitourinary fistulas, the first critical point to address is the patient's history. Symptom development following a recent surgery should be explicitly evaluated. Standard questions, including cancer radiation, obstructed labor, similar to the discussed patient, and trauma, should be raised. Specific symptom characteristics, including the leakage volume and or vaginal fluid color and smell, should be noted. The critical notion is to differentiate the urogenital fistula-related symptoms from other possible causalities of urinary incontinence. Accordingly, patients with urogenital fistula admit to changing heavy pads more frequently. Physical examination should be started with a split speculum examination.[9]

During the early post-traumatic phase, proceeding with physical examination under anesthesia and application of a dye test would be reasonable. Moreover, complex fistulas involving ureters are possible. To perform dye tests, several sterile fluid options, including sterile infant formula or indigo carmine, exist. The urethra would be compressed with the application of a gauze sponge while the bladder is being filled with colored fluid. In the absence of leakage over the placed tampon or cotton swabs, the next step is to ask the patient to cough. (to induce Valsalva maneuver). The color of the staining would discriminate the source of potential fistula. That said, if the tip of the tampon is blue-stained, a vesicovaginal fistula is suspected. However, clear fluid wetness is compatible with the presence of a uterovaginal fistula.[10]

Considering the imaging studies, cystoscopy is performed to evaluate several aspects, including the residual injury in the bladder and the number and characteristics of intravesical fistula orifices. Retrograde pyelography is performed to address the ureteral integrity. The major drawback with intravenous pyelography (IVP) is the potential for missing the ureteral leakage immediately adjacent to the trigone. Pelvic magnetic resonance image (MRI) is more sensitive than IVP or CT in diagnosing vesicouterine fistula. MRI has higher soft-tissue contrast compared to CT-cystogram. Specific further steps, including MRI or double-balloon urethral catheter under fluoroscopic guidance, may be helpful for the diagnosis of a complex urethral fistula or urethral diverticulum. Specific institutional-based protocols, including combined cystoscopy and vaginoscopy present to evaluate the suspicious or established vesicovaginal fistulas.[11][12]

The diagnosis is traditionally established utilizing clinical evaluation and dye testing. In addition to the methylene blue dye test described above, a "double-dye" test is also generally performed. This is accomplished by having the patient take oral phenazopyridine just before coming into the office.[13] A tampon or gauze is inserted into the vagina. Once the bladder is sufficiently full (indicated by an urge to urinate), the tampon is removed and inspected for orange-staining, and, if present, a genitourinary tract fistula is diagnosed. This could encompass a ureterovaginal or vesicovaginal fistula. The bladder is then back-filled with dilute methylene blue, as described above. If there is only orange-staining and no blue-staining of the tampon, a ureterovaginal fistula is most likely. If there is both orange and blue staining on the gauze then, a vesicovaginal fistula is likely but a concomitant uretetovaginal fistula cannot be entirely excluded. This can be further confirmed with imaging. Transvaginal ultrasonography, cystoscopy, and contrast studies may be utilized.[14]

Transvaginal ultrasonography may clearly visualize the exact size, site, and course of the fistula. Transvaginal sonographic evaluation is well-tolerated with a low side-effect profile and more instructive than some other conventional investigations.[15] However, sonographic findings are dependent on operator skill and experience and are infrequently used in the evaluation of fistulas. Cystoscopy is of particular help and can be used to identify the exact location of the fistula tract in the bladder. A small ureteric catheter or pediatric foley catheter can be passed through a suspected fistula tract to determine if and where it enters the vagina. Vaginoscopy can be performed in the office using the cystoscope and may aid in the localization of the fistula opening on the vaginal side. It is easily performed in the office and is well tolerated by most patients.[16]

Contrast studies, such as a multiphasic CT urogram, are recommended before proceeding with surgical repair to identify concomitant ureteral fistulas or abnormalities. More invasive and advanced techniques are generally not required but may include endoanal ultrasound or subtraction magnetic resonance fistulography.[17] Simple vesicovaginal fistulas are singular, small in size (<0.5 cm), and found in non-radiated patients with no evidence of malignancy involvement. A vesicovaginal fistula is considered intermediate in size if measured at 0.5 to 2.5 cm. Complex vesicovaginal fistulas are large in size (>2.5 cm), and associated with chronic disease, post-radiation, or failed previous fistula repair.[1]

Treatment / Management

For small, early-detected, and non-malignant vesicovaginal fistulas, conservative management can be pursued to help in the spontaneous closure of the defect. Conservative management includes transurethral foley catheter placement for 2 to 8 weeks along with anticholinergic medication if needed for symptom control. If a simple vesicovaginal fistula is diagnosed later in pathogenesis, electrocoagulation of the mucosal layer followed by transurethral catheter placement for 2 to 4 weeks could help in the closure of the defect.[18] Fulguration can be performed either cystoscopically or vaginally. Fibrin glue has also been described with varying results.[19](B2)

If conservative management fails, surgical intervention should be considered. A successful surgical intervention requires an accurate diagnosis, appropriate timing, and properly executed basic surgical principles. The surgeon’s training and expertise, as well as the type and location of the fistula, will determine the method of repair.[20] The best chance of a successful vesicovaginal repair is at the first surgical attempt. Definitive surgical repair can be complex, requiring interposition grafts from abdominal or vaginal repair approaches. If feasible, the vaginal approach is preferred and has high success rates. Complex vesicovaginal fistulas (related to pelvic irradiation) or recurrent fistulas may require the interposition of highly vascularized tissue for a chance at successful repair. (B3)

Postoperatively, the bladder should be continuously drained via a transurethral Foley catheter. When the vesicovaginal fistula involves the bladder neck, the catheter should be sutured in place and the balloon left deflated. Alternatively, a suprapubic catheter can be placed to avoid pressure from the inflated catheter balloon on the repair. The catheter should remain in place for 2 to 3 weeks following surgical repair. Cystography is often performed before catheter removal to determine the integrity of the repair. However, if this is not available, back-filling to the bladder to evaluate for vaginal leakage or an office cystoscopy are alternative options. Again, anticholinergics may be administered to manage catheter-associated irritative bladder symptoms. Prophylactic antibiotic coverage is not required while the indwelling catheter is in place. Pelvic rest for 6 to 8 weeks postoperatively is recommended.[21]

Differential Diagnosis

Postoperative or postpartum patients 1 to 2 weeks out from pelvic surgery or obstructed labor with a complaint of abnormal vaginal fluid leakage should be properly evaluated to determine the accurate diagnosis, and the clinician should have a high index of suspicion for a vesicovaginal fistula. The diagnosis is traditionally established utilizing clinical evaluation and tampon dye testing. A high creatinine level of the vaginal fluid can confirm the discharge is urine, but the clinician should be cautious in interpreting this as other types of urinary incontinence can also result in urine collecting in the vagina. Office cystoscopy and imaging studies are also often utilized in the evaluation. The differential diagnosis of postoperative or postpartum abnormal vaginal fluid leakage includes infection, inflammation, malignancy, urgency or stress urinary incontinence, or other urogenital abnormalities.[22]

Prognosis

Conservative measures for vesicovaginal fistula often fail, and surgery is pursued. The literature reports varying rates of successful surgical fistula repair, ranging between 70 and 100%, with a similar rate for transvaginal or transabdominal approaches, in non-radiated patients, at 91 and 97%, respectively.[3] A transvaginal approach to repair is typically less invasive and amenable to earlier repair.[2]  In one study, surgical repair of vesicovaginal fistula proved to be 100% successful (24 of 24 patients) when performed via the transabdominal route.[8] This same study showed an overall success rate of 87.5% (28 of 32 patients) for all first surgical correction attempts regardless of approach for simple vesicovaginal fistulas. In radiated patients, fistulas are less frequently repaired and can be much more complex. Success rates in radiated patients range from 40 to 100%. The interposition of flaps, such as those utilizing the labial fat pad or omentum, can provide a protective factor for recurrent cases.

Complications

The primary complication of vesicovaginal fistula surgery is recurrent fistula formation. Urinary frequency and urgency most commonly arise in the acute perioperative setting. Urgency and stress urinary incontinence are recognized as long-term complications of vesicovaginal repair. In obstetric causes for fistula formation where the sphincter mechanism is injured, stress urinary incontinence is common. Anticholinergic medication can be used to reduce symptoms for urgency symptoms. Stress urinary incontinence can be treated with the usual treatment for that disorder. Failure and recurrence occurred in 30% of vesicovaginal repair cases. In recurrent cases, consider a delay of 2 to 3 months from the previous attempted repair. Utilizing the interposition of flaps as a surgical technique should be considered to increase the chances of a successful repair.[23]