ETIOLOGY

Postoperative Iatrogenic Factors

Traumatic fistulas resulting from obstetric deliveries account for most UVFs in underdeveloped nations, whereas in industrialized nations,¹ UVFs occur as a complication of urethral diverticulectomy, anterior colporrhaphy, or other periurethral procedures. Some direct injuries are recognized at the time of the original surgery. In this instance, closure of the urethral lumen without verifying water-tightness, overlapping suture lines, lack of consideration for tissue interposition, insufficient bladder drainage, or a combination of these factors can contribute to the secondary formation of a UVF. Indirect mechanisms are less common but have been reported after periurethral collagen injection² and an anterior colporrhaphy during which tight suburethral plication resulted in tissue necrosis and secondary fistula formation.³ An unrecognized urethral injury, which can occur during urethrolysis and particularly in the setting of dense periurethral scar tissue after a sling procedure, is another indirect mechanism. Most contemporary series on synthetic slings using tension-free vaginal tape or transobturator tape report a low incidence of urethral injuries and secondary urethral erosions, which can result in UVFs.⁴^–⁶

Radiation Therapy

Although the incidence of vaginal fistulas occurring after irradiation for pelvic malignancies is significantly lower than in the past because of technical advances in radiation delivery, the profound long-term effects of radiation on surrounding tissues can promote fistula formation. Repair with flap interposition should be considered, but a supravesical diversion may be the only remaining option for heavily radiated tissues.

Other Causes

Vaginal lacerations after pelvic trauma, if ignored or inadequately repaired, can lead to UVF formation. Primary closure of vaginal lacerations is advocated to prevent fistula formation; regardless of the approach, these lacerations are susceptible to wound dehiscence if not properly débrided before repair.¹ Although rare, a neoplasm arising from a urethral diverticulum⁷ can extend locally and manifest as a UVF. Likewise, radiation therapy for urethral cancer can lead to tumor necrosis and a secondary UVF.

DIAGNOSIS

History and Physical Examination

Presenting symptoms may provide some insight as to the location and size of a UVF. Fistulas distal to the urethral continence mechanism may be entirely asymptomatic, or they may manifest as a split urinary stream or vaginal voiding. Occasionally, recurrent urinary tract infections are the main presenting symptoms. Women with larger fistulas or with fistulas involving the proximal urethra and bladder neck region present with continuous incontinence. It is important to review the prior operative notes, evaluate tissue quality (i.e., multi-operated, densely scarred, or atrophic tissues), and look for risk factors for deficient healing (e.g., immunosuppression, malnutrition, irradiation). Physical examination should identify the size and location of the fistula and any other associated fistulas or tissue changes. However, smaller tracts may be challenging to recognize, requiring endoscopy and imaging for exact determination. In some cases, a high index of suspicion despite thorough negative investigations may lead to urethrocystoscopy under anesthesia to establish the diagnosis.

Imaging

Visualization of the fistula tract may be accomplished by voiding cystourethrography ^8,⁹ or by double-balloon urethrography, but these techniques require high resolution to see the tract and true lateral views (Fig. 79-1). Upper tract imaging may be necessary for large or multiple fistulas to exclude ureteral obstruction or an associated ureterovaginal fistula. Urethral magnetic resonance imaging is of limited benefit to identify a fistula tract and is occasionally helpful in case of suspected residual diverticulum pocket associated with a UVF after urethral diverticulectomy.

Figure 79-1 Lateral view from voiding cystourethrography (VCUG) of a woman with a urethrovaginal fistula at the mid-urethra demonstrates a fistula tract, with contrast seen in the vagina. Good resolution and true lateral voiding films are important in visualizing the tract on VCUG.

Endoscopy

Direct visualization of the fistula opening on the floor of the urethral lumen with a short-beaked female urethroscope or a flexible scope can confirm the diagnosis.¹⁰ It is important to document the size of the opening and its location in the urethra in relation to the continence mechanism. The status of the bladder neck, trigone, and ureteric orifices should be observed, as well as the condition of the surrounding tissues for changes suggesting inflammation or neoplasm. A biopsy may be indicated for friable and irregular fistula edges or in case of a palpable induration around the fistula site. After vaginal laceration or urethral tear, the urethra may be completely strictured and the UVF located proximal to the site of urethral injury. Transvaginal endoscopy can help accessing the fistula tract and possibly the bladder by advancing a small flexible scope through the tract.

MANAGEMENT

The decision on how and when to best manage a UVF largely depends on the cause of the fistula, the quality of the surrounding tissues, the correction of risk factors for poor tissue healing whenever possible, and the number of prior repairs. Experience with urethral reconstruction procedures is paramount to achieving a good technical outcome. A large armamentarium of additional procedures to secure continence and prevent fistula recurrence should be available to the repairing surgeon.

Observation

Small fistulas in the distal urethra may be discovered incidentally and observed if minimally or asymptomatic. Spontaneous resolution of UVF with short-term catheter drainage has been reported.¹¹ Most patients, however, choose surgical repair.

Surgical Repair

The goals of UVF repair are to close the tract, prevent recurrence of the fistula, and restore continence as indicated. In the case of a small distal fistula tract producing a split urinary stream with minimal or no incontinence, a simple marsupialization procedure to create a hypospadiac opening (i.e., Spence procedure) may correct the problem.¹² We review two scenarios for transvaginal repair of a UVF, one involving a simple primary closure for a small nonirradiated UVF and the other a larger UVF necessitating more advanced techniques of urethral reconstruction and flap interposition for continence and closure.

Primary Closure with a Vaginal Flap

A primary repair using layered closure was first described by Collis,¹³ and it is ideal in the setting of a small to medium-sized UVF in nonirradiated tissues. Sterile urine must be obtained preoperatively, and antibiotic administration must be continued perioperatively. Several elements are necessary to facilitate a successful repair, as listed in Table 79-1. Patient positioning varies between advocates of the prone position¹⁴ and those preferring a high lithotomy position. Maximum perioperative urinary drainage is best achieved with a urethral and a suprapubic catheter. Exposure is facilitated by a Lonestar retractor (Lone Star Medi-cal Products, Stafford, TX) or other self-retaining retractor, a weighted vaginal speculum, a headlight, and even magnifying glasses if available. Passage of a Teflon guidewire over a 5-Fr open-ended ureteral catheter through the tract can facilitate the dissection of the tract (Fig. 79-2

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