Stress urinary incontinence is caused by weakened proximal urethral support and temporary loss of urethral sphincteric function due to bladder-neck descent during stressful physical activities.1,2 Effective nonsurgical treatments for genuine stress incontinence include properly taught pelvic-floor exercises and functional electric stimulation.3,4 Surgery provides the best long-term efficacy. In one study, the Burch colposuspension had a 90% 10-year success rate in curing genuine stress incontinence.5 Women with mixed incontinence, or the coexistence of stress and urge incontinence, also benefit from nonsurgical as well as surgical therapy. Women with surgically treated mixed incontinence do well, with only 31% continuing to have urge incontinence postoperatively.6
The Introl bladder-neck support prosthesis (UroMed Corporation, Norwood, MA) is a ring-shaped vaginal device with two prongs at one end (Figure 1). When placed in the vagina, the prongs sit alongside the urethrovesical junction in a retropubic position (Figure 2). The bladder neck is elevated, much as it is after a bladder-neck suspension.7 The initial clinical trial in women with genuine stress incontinence demonstrated an 80% dryness rate on standardized stress tests and marked reductions in urine loss based on bladder diary data.8
The purpose of this multicenter study was to evaluate the device's efficacy in a cohort of women with stress and mixed incontinence, with associated urethral hypermobility.
Materials and Methods
Volunteers with symptomatic stress or mixed incontinence were enrolled at eight centers. Institutional Review Board approval was obtained at each center, and written informed consent was obtained from all volunteers.
The evaluation consisted of a complete history and physical examination, including pelvic examination to assess pelvic supports. Urethral mobility was evaluated by a cotton-swab stress test. Laboratory testing included urinalysis and pregnancy test for those of child-bearing potential. Multichannel urodynamic evaluation included catheterized postvoid residual, uroflowmetry, urethral pressure profilometry, medium-fill subtracted water cystometry, and stress-cough urethral pressure profilometry. Provocative cystometry was done with the subjects standing and performing multiple provocative maneuvers. Urethral pressure profiles were done using a double-transducer microtip catheter withdrawn by a puller arm. A cough pressure transmission ratio was calculated in the proximal half of the urethra. After testing, all subjects received antibiotic prophylaxis for 24–48 hours.
Women were offered enrollment if their diagnosis was genuine stress incontinence or mixed incontinence with primarily stress symptoms. The diagnosis of genuine stress incontinence was based on urine loss symptoms, urine loss during exertion, and a positive stress-cough urethral pressure profile (pressure transmission ratio less than 90%). Mixed incontinence required a diagnosis of stress incontinence and uninhibited bladder contractions during the cystometrogram. All subjects had at least three episodes of incontinence per week and a stress cotton-swab angle of greater than 30 degrees from the horizontal plane. Specific exclusion criteria were determined based on the study requirements and the appropriateness for device usage (Table 1).
Severity of incontinence was assessed using a baseline 7-day bladder diary, standardized pad test, and validated quality-of-life questionnaire. The diary included daily voids, urgency, and incontinence events. The pad test was based on a previously tested routine.9 The Incontinence Impact Questionnaire, a validated, disease-specific incontinence quality-of-life tool, was completed by each subject.10 Scores were assigned for each designated aspect (social activities and relationships, travel and recreation, domestic activities) and composite scores were determined.
The prosthesis was available in 25 sizes, with diameters from 55 to 85 mm and prong lengths from 31 to 46 mm. The device should fit loosely in the vagina without compressing the urethra. Subjects were taught to insert the device by folding it lengthwise. For removal, the subjects were instructed to hook the anterior part of the ring with an index finger, rotate it counterclockwise, and pull it out.
After fitting, the subject was asked to perform provocative maneuvers (cough, jump, and heel bounce). If urine loss persisted, another device was fitted. Uroflowmetry and postvoid residual determination were then performed. If obstruction was suspected, a smaller device was fitted.
Subjects kept daily bladder diaries and were encouraged to wear the device during all physical activities. They were given weekly physical examinations focusing on vaginal mucosal changes. The size of the device was adjusted as needed. On the fifth visit, a complete physical and urodynamic evaluation was performed with the best-fitting device. Subjects completed the Incontinence Impact Questionnaire and a Prosthesis Attributes Questionnaire, which included questions on ease of insertion and removal, comfort with the device in place, and interference with daily physical activities.
Statistical analyses were based on comparisons of changes from baseline status using a paired Student t test. The assumption that the data were distributed normally was tested using the Shapiro-Wilk W test (with an alpha level of .01) and was not violated. Descriptive statistics were analyzed on the subjective evaluations of device use. An enrollment sample size of 66 was determined assuming a reduction in the number of urine loss events per week from 28 to 14 (50%) in each of the two groups and a standard deviation of 21 for the within-group change. This calculation is based on the published device efficacy,8 a two-sided paired t test, a power of 85%, a type I error of .05, and an expected dropout rate of 30% after the first 4 weeks of device fitting. Fisher exact test was used for statistical comparison of the dropout rates between groups.
Seventy women were enrolled and 53 (76%) completed the initial 4-week phase. Twenty-nine had genuine stress incontinence and 24 had mixed incontinence. The mean ages were 50.4 years for the genuine stress incontinence group (range 24–76) and 55.7 years for the mixed incontinence group (range 30–88).
Among subjects completing the 4-week study, 27 (51%) had had hysterectomies, 41 (77%) had cystoceles, 27 (51%) had restoceles, two (4%) had enteroceles, and four (8%) had vault prolapse. No subjects had prolapse to or beyond the vaginal introitus. Pelvic relaxation findings did not change significantly in any of the subjects during the study. Reasons for study discontinuation included inability to achieve satisfactory anatomic fit (eight), difficulty with removal (four), noncompliance with the protocol (two), relocation (one), and subject choice (two).
Pad testing and diary-recorded stress loss events demonstrated significant reductions in urine loss with the device in place (Table 2). Urodynamic data showed normalization of urethral support and function with the prosthesis in place in both groups (Table 3). Maximum urethral pressure was unchanged, demonstrating lack of urethral obstruction. The pressure transmission ratio, an index of dynamic urethral function during exertion, increased in both groups, reaching statistical significance in the genuine stress incontinence group. One subject with a stable bladder at baseline showed detrusor instability with the device in place, and two subjects with mixed incontinence (8%) had stable bladders with the prosthesis in place. Lack of urethral obstruction was confirmed by maintenance of normal postvoid residual volume and uroflowmetry indices with a prosthesis in place.
Subjects found that the device had a positive impact on their quality of life (Table 4). Both groups reported statistically significant reductions of incontinence impact on the social activities and relationships component. Subjects rated the device attributes including comfort, continence, and convenience highly (Table 5). Device removal received acceptable, although somewhat lower ratings. Adverse events included acute cystitis (five), vaginal soreness or irritation (13), and vaginal mucosal irritation (ten). All mucosal changes resolved with temporary interruption of device usage. No subjects reported worsening incontinence.
The bladder-neck support prosthesis decreased involuntary urine loss significantly in women with stress and mixed incontinence, using two objective incontinence quantification tools, pad testing, and bladder diaries. Quality-of-life scoring indices typically affected by genuine stress incontinence and mixed incontinence were also positively affected. There was no evidence of outflow obstruction with maintenance of physiologic voiding with the device in place. Improvement in urethral function was demonstrated by normalization of the pressure transmission ratio and the stress cotton-swab angle. These changes with the prosthesis in place are consistent with those seen after a Burch colposuspension.11
Because incontinence affects interpersonal aspects of life most dramatically, it is not surprising that the most marked quality-of-life changes were in the social activities and relationships component. The lowest attribute ratings were given for ease of removal. Although the women were asked to remove the device daily, it is likely that many women will leave the device in place for longer periods.
Urinary tract infections were more likely during the learning process of device insertion and removal. With practice, the degree of manipulation decreased, as did the risk of cystitis. Superficial vaginal mucosal abrasions were seen most commonly at the vaginal apex, where the device heel is located, or along the anterior vaginal wall at the site of the retropubic prongs. Any bleeding from the use of this device should be evaluated promptly. Women with atrophic genital changes should be encouraged to use vaginal estrogen cream to reduce the risk of mucosal damage.
Many women reported using the device primarily during activities associated with urine loss, such as exercise. Being able to individualize usage patterns is an attractive feature. Other possible applications include temporary use until surgery is appropriate, empiric use in women with symptomatic stress incontinence, use as a trial device in women with mixed incontinence with marked urgency, and use as a prognostic tool in women planning to have anti-incontinence surgery.
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