10 Urethral Diverticulectomy
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The true incidence of female urethral diverticulum is not known. It has been estimated to occur in 0.6% to 6% of females. Some have argued that urethral diverticulum is underdiagnosed and that with a higher level of clinical suspicion the incidence might be greater; however, this has yet to be proved. Urethral diverticulum may occur as a result of infection of the periurethral glands with obstruction and local abscess formation, or due to trauma from childbirth or instrumentation. A congenital origin has also been proposed; however, the absence of urethral diverticulum in children and adolescents makes this a less likely etiology.
There are a myriad of symptoms that are thought to be caused by a urethral diverticulum. The classic triad of dysuria, dyspareunia, and dribbling is present in fewer than half of diagnosed cases. Other symptoms include frequency, urgency, recurrent urinary tract infections, urethral pain, tender mass, stress or urge incontinence, hematuria, urethral discharge, difficulty voiding, and urinary retention.
In many cases the diagnosis of urethral diverticulum is made (or suspected) on physical examination. The presence of a suburethral mass, often tender, with expression of discharge by urethra when the anterior vaginal wall is massaged is a typical finding. The differential diagnosis includes cystocele, anterior vaginal wall cyst, adenoma, and ectopic ureter. In these cases there is no expression of urethral discharge on palpation. The diagnosis can be confirmed by a number of imaging tests, including voiding cystourethrography (VCUG), ultrasonography, and magnetic resonance imaging (MRI). We prefer to obtain an MRI scan in all cases of known or suspected urethral diverticulum because it precisely defines the anatomy (size, location, shape, and number of diverticula) and aids in surgical dissection and removal (Figs. 10-1 through 10-3). A diverticular ostium is seen on urethroscopy in most, but not all, cases. Although urethroscopy can identify the location of the urethral communication, it tells nothing about the size, location, and anatomy of the diverticulum itself. Also, in cases of urethral pain, urethroscopy can be painful and at times even impossible with only local anesthesia. In those cases we reserve urethroscopy for the operating room at the time of surgical excision.
Figure 10-2 Small urethral diverticulum in a highly symptomatic woman with urethral pain and tenderness. Voiding cystourethrography and cystoscopy yielded normal findings. A, Axial image. B, Sagittal image.
Figure 10-3 Axial magnetic resonance image (left) reveals a large circular diverticulum that is deficient ventrally. This information was invaluable at surgery, when a fibrous band of tissue was found and the diverticulum was identified laterally on both sides (right). (See Case #3.)
Ancillary testing can be performed in certain circumstances. For example, when stress incontinence is suspected, urodynamic testing can confirm the diagnosis. This could lead the surgeon to decide to perform an antiincontinence procedure at the same time the diverticulum is repaired.
The decision to treat urethral diverticulum is often based on the severity of the presenting symptoms. In cases of an asymptomatic urethral diverticulum, treatment is not mandated. Often an asymptomatic diverticulum is discovered on a routine physical examination or an imaging study done for another reason. Little is known about the natural history of an asymptomatic diverticulum and whether it will increase in size or become symptomatic in the future. The occurrence of carcinoma within a urethral diverticulum is well recognized, because cases of squamous cell carcinoma, transitional cell carcinoma, and adenocarcinoma have been reported. Thus, patients with an asymptomatic urethral diverticulum must at least be warned of this risk.
Symptomatic patients will often opt for treatment. A variety of surgical techniques have been described, but we adhere to the principle of excision and urethral reconstruction. Other techniques of treatment include marsupialization by a transurethral or open approach, fulguration, and endoscopic unroofing. We believe that excision and urethral reconstruction gives the best long-term results with maximal preservation of urethral function. In addition, it allows the surgeon to simultaneously treat stress urinary incontinence when present. Before surgical repair we attempt to treat any active infection. In addition to the techniques described later, a urethral excision with end-to-end urethroplasty for correction of a large circumferential diverticulum has been described by Rovner and Wein.
As mentioned previously, it is a great help to the surgeon to know the exact location, the shape, the approximate size, and the number of diverticula before the surgery is begun. This will help the surgeon plan the dissection once the diverticulum is encountered to allow complete excision of the diverticulum without excision of normal urethra.