Although rare in the United States and more common in low-resource countries, fistulas due to obstructed labor do occur. In developed countries, other obstetric causes for fistula are usually surgery, trauma, or infection related. An abnormal communication between organs—be it the urethra, bladder, ureter, uterus, cervix, or rectum—can develop1 and lead to vesicovaginal fistula (VVF), urethrovaginal fistula (FIGURE 1), vesicocervical fistula, vesicouterine fistula, ureterovaginal fistula (FIGURE 2), and rectovaginal fistula (RVF). Other nonobstetric causes include gynecologic surgery, radiation, malignancy, and congenital malformations.
During labor, hypoxia, subsequent ischemia, and pressure necrosis contribute to fistula formation. Injury sustained during a cesarean delivery (CD) or cesarean hysterectomy can lead to fistula formation; at times, however, complications are unavoidable given the nature of the pathologic condition that the patient presents with.
VVF and RVF have a devastating impact on a woman’s quality of life as they lead to significant morbidity and short- and long-term psychological distress. The fistula may not be recognized at the time of injury. The presenting signs and symptoms may be intermittent and confusing. Immediate surgical intervention may not be possible due to ongoing inflammation or infection. Recovery often is prolonged. As there is significant concomitant postpartum anxiety and depression, patients with fistula often require psychosocial support and counseling. After repair, there is still a risk for recurrence and voiding dysfunction.
Fistula signs and symptoms and evaluation
In cases of VVF, patients present with continuing large or small volume urinary incontinence. Depending on the time to diagnosis, patients may have calculi formation, prolapse, scarring, external perineal dermatitis, perineal nerve injury, and even motor weakness. Cyclic hematuria may be seen in vesicouterine fistulas.2
Multiple classification systems for diagnosis and staging of VVF have been suggested.3,4 A classification system for RVF was published by Tsang and colleagues.5 All these classification systems have attempted to characterize fistulas in terms of level of surgical complexity for repair, providing a guideline for preoperative assessment. These classification systems do not translate into prediction regarding outcomes.
Evaluation of pelvic fistula from the urinary tract starts with a thorough history that includes onset, duration, and description of leakage (continuous, intermittent, or positional) and whether there is concomitant stress and urge incontinence. A detailed obstetric history, including circumstances around the mode of delivery, underlying risk factors, and psychosocial history, should be obtained.
The pelvic examination with a plastic speculum and adequate lighting should assess the external perineum for dermatitis; bulbocavernosus and anal reflexes; and the vagina for length, caliber, level of scarring, and any prolapse. For VVFs, the location, size, and number of the fistula tracts can be visualized and confirmed with a retrograde fill of the bladder via a Foley catheter with saline or water mixed with methylene blue or any other blue dye (FIGURE 3). If a ureterovaginal fistula is suspected, the patient can simultaneously be given oral phenazopyridine and a tampon inserted within the vagina; the patient can then ambulate, and re-examination of the end of the tampon can reveal orange staining. The bladder meanwhile is retrograde filled with blue dye, with no blue staining of the tampon.
For RVF, history taking should include the onset, duration, and description of leakage, and the external anal sphincter should be assessed, with careful examination of the distal vagina at the vestibule as this is the most common location for RVF (fistula in ano). Patients may describe vaginal flatus and sometimes only brownish discharge, which can be intermittent, leading to an incorrect diagnosis of vaginitis that is treated repeatedly without success.
There is no consensus regarding optimal imaging for the assessment of VVF. Imaging used for diagnosis of VVF includes a voiding cystogram with opacification of the vagina after filling the bladder with contrast if there is a fistula. A cystoscopy can evaluate for calculi, retained suture, level of inflammation, and location of the ureters in relation to the fistula. Renal ultrasonography is of limited use. Intravenous pyelography can miss lesions by the trigone. In general, a computed tomography (CT) urogram and magnetic resonance imaging (MRI) with bladder contrast are more sensitive.
In the diagnosis of RVF, contrast vaginoscopy, double contrast barium enema, CT scan with contrast, and MRI can be used. MRI is more sensitive.6 A high index of suspicion is required based on the patient’s history as these imaging modalities do not always confirm RVF despite patient’s clear history of leakage. When the history is convincing, a thorough rectovaginal exam under anesthesia may be imperative. If rectal trauma is present, endoanal ultrasonography can delineate external and internal anal sphincter defects.
Prolonged Foley catheter placement after obstetric injury can lead to successful closure of a VVF. Prior to surgical intervention, assessing if there is possible ureteral involvement and use of intraoperative ureteral stents is a consideration. The route of surgery can be vaginal, abdominal, combined abdominal-vaginal, laparoscopic, or robotic.7 The robotic approach is increasingly utilized.8,9 However, the general consensus among fistula surgeons is that the vaginal approach should be considered first.
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