By Kathleen C, Kobashi, M.D.
and Gary E. Leach, M.D., F.A.C.S.

Stress urinary incontinence (SUI) is defined as the involuntary loss of urine with increased intra-abdominal pressure, without a concomitant detrusor contraction. When treating SUI, the goal is restoration of urinary continence without retention. In this article, we discuss patient evaluation and selection and present a wide range of treatment options.

Patient Evluation
At our institution, we use the sling as the primary procedure for all patients with demonstrable SUI, and our evaluation is tailored accordingly. To determine the best course of treatment, each patient must be carefully evaluated to establish whether they have SUI alone or mixed incontinence. The possibility of detrusor instability can be evaluated on urodynamics by demonstrating a stable bladder or lack of symptoms of urgency during bladder filling. We believe that detrusor instability or symptoms of urgency (sensory instability)-if present-should be controlled with medications prior to sling placement.

As Haab and colleagues described in their series, patients with pure SUI are more likely to be dry following sling placement when compared with patients with mixed stress and urge incontinence (66% vs. 36%, respectively).1 These authors also consider slings an option in patients with detrusorinstability that occurs only at high intravesical volumes and in patients with low-pressure detrusor instability that does not correlate with their symptoms.

Patient evaluation includes a detailed history, physical examination, and urodynamic studies. Cystourethroscopy and radiographic studies are also often useful. History. Frequency of urination, degree of leakage, and history of urinary tract infections help assess the character of a patient's incontinence. The degree of incontinence may be quantified by the number and type of pads a patient uses for protection. The clinician should note whether the symptoms a patient describes are typical of stress, urge, or mixed incontinence. Symptoms of SUI include urinary leakage with coughing, sneezing, or exercising. In severe cases, particularly in patients with intrinsic sphincter deficiency (ISD), patients may complain of leakage with minimal motion or change in position. Symptoms of urge incontinence include a sudden uncontrollable urge to void with resultant leakage. As many as 65% of patients with SUI have mixed stress and urge incontinence.2 To provide proper treatment for these patients, it is important to determine which of the 2 symptoms poses the primary problem.

Carefully note any symptoms that may suggest neurologic disease or sacral arc (S2-S4) denervation. Symptoms include blurred or double vision, altered sensation or motor strength of the lower extremities, bowel incontinence, or decreased sensation of bladder filling. Previous back injury or surgery and established neurologic disease (such as Parkinson's disease or multiple sclerosis) can contribute to incontinence. Other important data, including past medical and gynecologic history and number of pregnancies and difficult deliveries, may indicate pelvic floor weakness or nerve injury, which can contribute to urinary incontinence.

Check the patient's medications such as a-blockers, which may exacerbate or unmask SUL A review of past surgical history, particularly any abdominal, pelvic, or previous hysterectomy or anti-incontinence procedures, provides essential data for making proper therapeutic and surgical decisions.

Physical Examination. As the current trend moves toward the use of slings for all types of SUI, the presence or absence of urethral hypermobility is becoming less significant. Nonetheless, this information is important for patients who opt for periurethral injection therapy, typically performed in those who have well-supported urethras and ISD.

The presence of periurethral scarring may necessitate urethrolysis prior to sling placement to facilitate adequate urethral compression by the sling. Additionally, we advocate repair of any pelvic prolapse at the time of sling placement to minimize the risk of postoperative urgency, urge incontinence, or exacerbation of urinary retention. Finally, a focused neurologic examination, including perineal and lower extremity sensation, lower extremity strength, bulbocavernosus reflex, deep tendon reflexes, and anal sphincter tone, must be performed to exclude any abnormalities that may contribute to incontinence.

Urodynamics. Multichannel urodynamic studies are used to evaluate detrusor and sphincter function and demonstrate the incontinence. These studies help assess a range of factors including sensation of filling, continence status, bladder capacity and compliance, and ability to empty the bladder. We consider urinary retention, limited bladder capacity, and symptomatic detrusor instability during filling to be relative contraindications to primary sling placement. This minimizes the risk of postoperative urgency, urge incontinence, or exacerbation of urinary retention.

According to Haab and associates, however, the only predictive factor for failure of a sling is preoperative urgency.1 During cystometry, they stop filling approximately every 100 cm3 to check for SUL Patients are asked to perform provocative maneuvers such as coughing, walking in place, or jumping to demonstrate incontinence. They then have patients strain (Valsalva's maneuver) to demonstrate the leak point pressure (the vesical pressure at which leakage occurs is termed the Valsalva or abdominal leak point pressure). This technique is problematic, however, because results are not standardized or reproducible, and leak point pressure values that imply ISD have been set arbitrarily. Nonetheless, with slings now being used as the primary procedure for all types of SUI, Valsalva leak point pressure may have less clinical relevance.

Other Objective Studies. Cystourethroscopy is performed to exclude other bladder or urethral pathology (such as diverticuli, tumors, stones, or foreign bodies within the bladder or urethra). In patients with significant cystocele, we recommend upper tract evaluation with renal ultrasonography to rule out obstruction caused by kinking of the ureters.

Treatment Options
Patients with SUI may respond to a range of treatment alternatives, including pharmaceutical agents, biofeedback and behavioral therapy, perzurethral and transurethral injection of bulking agents, and a variety of surgical techniques. Pharmacotherapy. In patients with mixed incontinence in which urge is the predominant issue, anticholinergic treatment is initiated first (Table 1). In our experience, the residual SUI after the detrusor instability is adequately controlled may be minimal, and the patient may elect not to proceed with further treatment. An excellent first line of therapy is imipramine, which relaxes the detrusor muscle and increases the tone of the bladder neck and proximal urethra by direct -adrenergic stimulation.

Although other anticholinergic medications may also be used, they clearly do not treat ISD. In theory, -agonists may be useful in increasing bladder outlet resistance. While some clinicians have reported good success with -agonists in the treatment of SUI,3,4 our experience with using medications alone has produced variable success with only rare total cure. Nonetheless, in patients who are unable to undergo surgery or who choose a nonsurgical route, -agonists may improve continence.

Local estrogen therapy with vaginal cream should be considered in patients who have atrophic changes in the vagina and who have no contraindications to such estrogen therapy. We prescribe intravaginal administration of one-third applicator of estrogen cream, 3 times a week. Estrogen enhances the effects of -agonists (perhaps by increasing the density of -receptors), promotes mucosal proliferation, and increases submucosal blood flow, thereby enhancing the mucosal seal effect.5

Biofeedback. In very mild cases of SUI, in which leakage may not even be demonstrable in the office setting, biofeedback may be useful. A study by Stein and colleagues showed moderate success when 5 (36%) of 14 patients experienced a significant decrease in SUI symptoms following 6 biofeedback sessions over a 3-week period.6 Patients who choose biofeedback must be advised that long-term success is feasible only if they faithfully continue the exercises after their course of biofeedback.

Biofeedback can also be used to control mild preoperative detrusor instability or persistent de novo urgency after sling placement. Burgio and associates demonstrated the efficacy of biofeedback as compared with anticholinergic medications or placebo in patients with urge incontinence or mixed incontinence with urgency as the primary component.7 With a mean follow-up of 6 years, the biofeedback group had the greatest objective (80.7%) and perceived (74.1%) improvement as compared with the medication group (68.5% and 50.9%) and the placebo group (39.4% and 26.9%).

Injection therapy. When the bladder neck and proximal urethra are well-supported, injection therapy proves most useful. Various materials, such as collagen, polytetrafluoroethylene (Teflon), and fat, have been used in periurethral injection therapy for ISD. Currently, bovine collagen is the only material approved by the FDA for injection therapy in the United States. Collagen serves to increase coaptation of the urethral mucosa at the sphincter. It is injected either transurethrally or periurethrally under endoscopic visualization into the submucosal tissue of the urethra. Complications with collagen injection, although rare, include tissue necrosis at the injection site, urethral prolapse, delayed hypersensitivity with systemic arthralgia, bladder outlet obstruction, pseudocyst formation, and sterile abscess formation.8

The general success rates of collagen injection therapy are 60%o to 70%.9 In our experience, patients require an average of 2 to 3 injections, usually within the first year. In a study by Cross and associates, approximately 30% of patients are dry, 30% are improved, and 40% fail injection therapy.9 Of the dry patients, 20% require reinjection of collagen approximately every 12 months. Patients who defer or fail injection therapy are offered surgical therapy. In a review of 139 patients who underwent periurethral collagen injection therapy (median follow-up, 18 months; range, 6-36 months), Cross and associates found that 103 (74%) noted "substantial" improvement, 29 (21%) noted improvement, and 7 (5%) experienced no change. 9 The average duration since the last collagen injection was 18 months. Thirty-nine patients (28%) developed de novo urgency, 29 (20.8%) had persistent urgency, and 16 patients (11.6%) required a "booster injection" more than 6 months after the first injection.

Surgical Therapy. The AUA Clinical Guidelines panel on the surgical treatment of female SUI reviewed the medical literature published in English and found an 82% to 84% success rate for pubovaginal slings and retropubic suspensions at 48 months' follow-up.10 Sling procedures- traditionally the treatment of choice for ISD11 -have recently become the gold standard for treatment of all types of SUI because they provide both support and compression of the urethra with excellent long-term results. Retropubic suspensions do not provide any compression of the urethra and are not used to treat IBD. In cases of poor urethral function (low leak point pressure), repositioning of the proximal urethra and bladder neck with a retropubic suspension alone will not restore continence.

Patients with mixed incontinence who complain primarily of SUI have a 60% to 80% chance of resolution of the urgency following sling placement. Persistent postoperative urgency, which occurs in 20% to 40% of patients, is often more difficult to treat successfully after a sling procedure than before the surgery.12-14 The risk of de novo urge incontinence ranges from 3% to 19%,12-15 and the risk of permanent retention is only 1% to 2%.12 In the authors' experience, less than 1% of patients had permanent urinary retention following sling placement, and approximately 30% of patients required postoperative temporary self-catheterization (<1 week).

Of the numerous techniques employed for sling placement and the various materials of different sizes used to create slings, we prefer to anchor a strip of cadaverlc fascia to the pubic bone via a transvaginal approach (see "Surgical technique for cadaveric transvaginal sling," above).
Artificial urinary sphincter. At our institution, we do not use the artificial urinary sphincter in women; however, others have reported satisfactory experience. 16,17 Sutaria and Staskin reported an 86% dry rate in 106 female patients treated with artificial urinary sphincters after a mean follow-up of 3.8 years.16

The artificial urinary sphincter requires surgical placement of a prosthetic cuff around the urethra. Our main concern is atrophy of the female urethra beneath the 2-cm cuff. Damage to the short female urethra could necessitate urethral reconstruction or urinary diversion. Additionally, artificial urinary sphincters are costly, have the inherent risk of mechanical failure, and often cause patients pain and discomfort at the site of the prosthetic device. In cases of an infected prosthesis, the device must be removed, after which control of continence may be difficult to achieve. We believe that with the high success rate of the sling, artificial sphincters in women are rarely indicated.

Conclusion
Developments in the field of urinary incontinence continue to evolve with advances in technology and techniques. As concluded by the AUA Guidelines panel, the sling procedure is the most efficacious long-term surgical treatment for SUI.10 The trend in surgical therapy is toward slings for all types of SUI in patients who are surgical candidates. We believe the cadaveric transvaginal sling approaches the goal of maximal benefit with minimal invasiveness, showing excellent early results and a significant decrease in invasiveness. Longer follow-up will be reported as available.

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