Postoperative Urinary Fistulae – Dec 2009
A 38-year-old patient presents seven days following a difficult hysterectomy and bilateral adnexectomy for severe endometriosis with the complaint of having continuous urinary incontinence, possibly from the vagina. She wishes for this problem to be evaluated and treated.
Postoperative urinary tract fistulae are one of the many risk factors associated with pelvic surgery. It is estimated that the risk of injury to the urinary tract is about 1% and many of these injuries are occult at the time of surgery. Obviously, any recognized injury at the time of surgery should be repaired at that time. Occult injuries of either the bladder or ureters may subsequently result in the leakage of urine outside of the urinary collection system. This urine may then track to the vaginal cuff and spontaneously drain, resulting in either a vesicovaginal fistula or a ureterovaginal fistula.
While fistulae can result in an anatomically normal surgical field, the most common risk factor associated with urinary fistulae after pelvic surgery is the presence of anatomical distortion. The etiology of the distortion can be varied and multiple. Common causes of anatomical variances include embryologic anomalies (e.g. double ureters), prior surgeries (e.g. C-sections, renal transplants), fibroids (especially if they are paracervical), severe endometriosis, severe acute or chronic inflammatory disease (including fibrosis from prior surgery or radiation), and cancer.
Preventive strategies are worthy of consideration. Preoperativve imaging may help define unsuspected anatomical distortion. During the surgical procedure, optimal exposure of adjacent anatomical structures should be maximized. In general sharp, rather than blunt dissection is advisable, especially for the vesicouterine plane following one or more C-sections. The placement of ureteral stents preoperatively may be of some help, however some have suggested that they may increase the risk of injury to the ureter. In general, ureteral stents are not required to aid in the identification of normal anatomy.
In the patient presenting above, one should review the history, including the details of the surgery and perform a focused pelvic examination. If fluid is pooling in the vaginal vault, one investigation that may be useful is to collect the fluid for a creatinine. A result significantly above the normal serum creatinine will confirm the fluid is urine. One of the differential diagnoses in surgical cases that include pelvic lymphadenectomy is that of lymphatic fluid draining from the site of dissection through the vaginal vault. In this circumstance, the vaginal fluid creatinine will be similar to that of the patient's serum creatinine.
One of the simplest diagnostic tests to assess for a vesciovaginal fistula is to perform the "tampon test". Sponges or tampons are placed in the vagina and the bladder is filled with an identifiable fluid, usually methylene blue. The patient is then asked to walk around for a short interval before being examined. The presence of blue dye on the tampons or sponges, suggests a defect from the bladder to the vagina. If there is no staining, but a urinary fistula is strongly suspected, then the next site of suspicion is one of the ureters. The ureters are best evaluated with an intravenous pyelogram, although a well-performed retrograde pyelogram can provide similar information.
Management of postoperative fistulae can often be conservative. Many small vesicovaginal fistulae will close if the bladder is continuously drained with a Foley catheter. The addition of estrogen or urinary antibiotics may also facilitate the healing process. If a ureteral defect is noted, this defect may spontaneously heal if it is possible to place a ureteral stent. Usually the first attempt to do place a ureteral stent is using the retrograde approach. If this fails, then placement of a percutaneous nephrostomy, with subsequent antegrade stent placement is advised. Of course, if conservative management is neither possible nor successful, then surgical intervention may be necessary to resolve the defect.