Successful colposuspension in stress urinary incontinence reduces bladder neck mobility and increases pressure transmission to the urethra

Summary Twenty-nine consecutive patients with stress urinary incontinence were investigated by bead chain urethrocystography (UCG) and single cough urethrocystometry before operation and 8–12 months after a Burch colposuspension producing clinical improvement. The operation significantly elevated the bladder neck and reduced its mobility during acute stress. the urethral inclination angle and the posterior urethrovesical angle also became smaller at rest and on straining. A significant negative correlation was found between the postoperative mobility of the bladder neck and the post-operative pressure transmission ratio (PTR), indicating that correction of the urethrovesical anatomical disorder eliminates the functional disorder in this disease and restores continence.     

Role of cystourethrography in the preoperative evaluation of stress urinary incontinence in women

Thirty-two women with stress urinary incontinence and 27 control continent patients with pelvic relaxation underwent a detailed clinical and urodynamic evaluation of the lower urinary tract. All patients underwent a standard chain urethrocystographic evaluation to detect anatomic pathology of the lower urinary tract. Urethrocystographic study included an evaluation of the posterior and anterior urethral angle, funneling of the proximal urethra on straining, the position of the urethrovesical junction and flattening of the bladder base. No differences were seen in the incidence of radiographic findings in women with pelvic relaxation with or without stress urinary incontinence. All five cystographic criteria were similar in the continent and stress incontinence patients. Static urethrocystography cannot differentiate women with and without stress urinary incontinence from among those with pelvic relaxation and thus should not be relied upon in the evaluation of women with urinary incontinence.     

Urethral axis and sphincteric function

Position and mobility of the urethral axis are considered factors influencing urethral competence. Specific correlation between the urethral axis and its sphincteric function is lacking. Eighty-four patients with the symptom of stress urinary incontinence and 31 patients with sensory symptomatology but not urinary incontinence underwent clinical and urodynamic evaluation. This included objective assessment of urethral axial positions and mobility with use of a specially designed protractor. Comparative analysis of urethral axial data was done between 70 incontinent women with objective evidence of sphincteric incompetence and 24 continent women without it. The urethral axis at rest, during bearing down, and in its total excursion were found to be not significantly different and distributed similarly between both groups. Assessment of the urethral axis was found to be not predictive of urethral function.     

Correlation between urodynamic test results, perineal ultrasound and degree of stress urinary incontinence

OBJECTIVE: To evaluate whether the results of urodynamic tests and the perineal ultrasound were different between grade 1 and 2 stress urinary incontinence. STUDY DESIGN: Forty premenopausal women with a diagnosis of stress urinary incontinence according to urodynamic tests were enrolled in this study. Stress urinary incontinence was defined as urine leakage during stress without detrusor contraction. Twenty patients had grade 1 and 20 had grade 2 stress urinary incontinence. We compared the parameters of uroflowmetry, filling cystometry, urethral pressure profile, dynamic urethral function test, perineal ultrasound and stress urethral axis between grade 1 and 2 levels of stress urinary incontinence. RESULTS: There were no significant differences in age, parity or body mass index between the grade 1 and 2 patients. Uroflowmetry results showed that there were no significant differences in maximal flow rate, average flow rate, voided volume or residual urine between grade 1 and 2. As to cystometry results, only the first desire to void was significantly increased in grade 2 over 1 (304 +/- 113.65 vs. 194 +/- 48.24 [mL], P = .04). There were no significant differences in any of the urethral pressure profile parameters. In the dynamic test, the Valsalva leak point pressure and cough leak point pressure were not significantly different between the 2 groups. There were no significant differences in perineal ultrasound parameters or the stress urethral axis. CONCLUSION: Most stress urinary incontinence-related parameters showed no difference between the grade 1 and 2, and no urodynamic or ultrasonographic evidence for a difference between the grade 1 and 2 was demonstrated.     

Is urethral mobility really being assessed by the pelvic organ prolapse quantification (POP-Q) system?

OBJECTIVE: To estimate the relationship between Q-tip measurement of urethral hypermobility and visual assessment of the urethrovesical junction as assessed by points Aa and Ba of the pelvic organ prolapse quantification (POP-Q) system. METHODS: A total of 274 patients with pelvic organ prolapse or urinary incontinence had preoperative Q-tip test straining angles and POP-Q staging measurements. By the Q-tip test, urethral hypermobility was defined as a straining angle of 30 degrees or greater relative to the horizontal. As defined in the POP-Q system, point Aa is located in the midline of the anterior vaginal wall 3 cm from the external urethral meatus and represents the urethrovesical junction. Point Ba represents the most dependent position of the anterior vaginal wall. The correlation between point Aa of the POP-Q system and the Q-tip test was assessed using the Spearman correlation coefficient. Similar assessments were made for point Ba. RESULTS: Mean age of the 274 subjects was 58.5 +/- 11.8 years; mean parity was 3.1 +/- 1.6. A total of 104 patients reported prior surgery for prolapse or incontinence. Mean Q-tip straining angle was 61 +/- 20 degrees; 258 (94%) had urethral hypermobility. Values of point Aa ranged from -3 cm to +3 cm, with median 0 cm. The correlation coefficient between the Q-tip straining angle and point Aa was r = 0.47 (P <.001). Urethral hypermobility was observed in 95% of patients with stage II prolapse at point Aa and in 100% of patients with stages III and IV prolapse at point Aa. The correlation coefficient between the Q-tip straining angle and point Ba was r = 0.32 (P <.001). CONCLUSION: Although the correlation between the Q-tip straining angle and point Aa of the POP-Q was moderately strong, one value cannot be predicted from the other. The Q-tip test may be unnecessary in patients with stages II, III, and IV prolapse at point Aa as virtually all such patients demonstrate urethral hypermobility.     

Correlation of Q-tip values and point Aa in stress-incontinent women

OBJECTIVE: To estimate the relationship between pelvic organ prolapse quantification (POP-Q) point Aa and straining Q-tip angle. METHODS: We compared preoperative straining Q-tip angles and Aa measurements from 655 women with predominant stress incontinence and urethral hypermobility (defined as a resting or straining angle of greater than 30 masculine) using Pearson correlations and linear regression. Point Aa is 3 cm deep to the urethral meatus in the midline of the anterior vagina and corresponds to the urethrovesical crease. RESULTS: The median for point Aa was -1 cm (range -3 to +3 cm) and for straining Q-tip was 60 masculine (30-130 masculine). Twenty-nine percent of participants had an Aa at least 2 cm deep to the hymen, whereas in 69%, Aa was at or below -1 cm. The straining Q-tip angle was significantly different between these respective groups: 51.5 masculine and 64 masculine (P<.001). Linear regression analysis indicates that point Aa and straining Q-tip were moderately correlated (r=0.35, P<.001). As straining point Aa increased by 1 cm, Q-tip angle increased 4.6 masculine (P<.001). Age and prior anterior vaginal or incontinence surgery had no significant effect on the correlation (P=.08 and P=.64, respectively). CONCLUSION: Nearly a third of stress-incontinent women with urethral mobility by Q-tip test visually appeared to have a well-supported urethrovesical junction with POP-Q point Aa values of -2 cm or less. The position of the urethrovesical crease (point Aa) on POP-Q and straining angle on Q-tip test do not appear to reflect the same anatomic support and cannot be used to predict one another. No Aa value can rule out urethral hypermobility.     

Urodynamic results of Burch colposuspension

Between 1984 and 1987 31 patients underwent a colposuspension according to Burch for stress urinary incontinence. Seventeen women were available for clinical and urodynamic follow-up after an average of 17.6 months. Clinically, 2 women had postoperative stress-urge incontinence and 2 had stress incontinence only. 13 (77%) patients were continent while straining, 9 (53%) patients complained of urge and voiding disorders, 7 reported post micturition dribble, 2 patients lost urine during intercourse. Urodynamically, 14 (82%) patients were continent during straining, 3 showed mild stress incontinence. The functional urethra length and urethral closure pressure at rest were unchanged. The urethral pressure under stress, depression quotient, and transmission factor increased significantly. The average uroflow sank from 16.8 ml/s to 7.8 ml/s, reflecting the subjective voiding disorders. Bladder compliance was unchanged. We saw no autonomous detrusor contractions and thus no correlation with subjective urge complaints.     

The short-term effect of radical hysterectomy on urethral and bladder function

To investigate bladder neck and urethral function after radical hysterectomy, 21 patients were investigated before and 3 months after the operation. Each patient had an excretory urogram, CO2 cystoscopy, uroflowmetry, water cystometry and a urethral pressure profile, using a dual sensor microtransducer catheter, at rest and during stress. Postoperatively there was a significant reduction in urethral length and urethral closure pressure; however, pressure transmission ratios were maintained, indicating no loss of bladder neck support with stress. Of the six patients with pre-operative bladder neck weakness, two (33%) had stress urinary incontinence at the 3 months assessment. No patient with a normal pre-operative assessment developed this complication. Fifteen (71%) voided by abdominal straining and this manoeuvre emptied the bladder effectively. These data suggest that patients with pre-operative evidence of an incompetent bladder neck may be predisposed to develop stress urinary incontinence after radical hysterectomy because of a reduction in the urethral closure pressure.     

A comparative study of perineal ultrasound scanning and urethrocystography in patients with genuine stress incontinence

Summary Perineal scanning using linear array ultrasound was used as an alternative to radiologic urethrocystography in the investigation of female urinary incontinence. The posterior urethro-vesical angle () and the angle of inclination () of 30 patients (age: 48±10.2 years) with genuine stress incontinence were measured by both procedures. In all cases the radiologic and ultrasound findings correlated well. Perineal scan provides similar information to that obtained by the radiographic procedure without exposure to X-rays. In contrast to urethrocystography perineal scan is fast, inexpensive, readily accessible and more acceptable to the patient.     

Two- and 3-dimensional MRI comparison of levator ani structure, volume, and integrity in women with stress incontinence and prolapse

OBJECTIVE: The aim of this study was to identify imaging markers for genuine stress incontinence and pelvic organ prolapse by using magnetic resonance imaging and reconstructed 3-dimensional models. STUDY DESIGN: Thirty women were studied, 10 with prolapse, 10 with genuine stress incontinence, and 10 asymptomatic volunteers. Axial and sagittal T1 and T2 weighted pelvic magnetic resonance scans were obtained with the patient in the supine position. Source images were measured to determine levator hiatus height, bladder neck to pubococcygeal line, levator plate angle, and perineal descent at rest and maximum Valsalva. Manual segmentation and surface modeling was applied to build 3-dimensional models of the organs. The 3-dimensional models were measured to determine levator muscle volume, shape and hiatus width, distance between symphysis and levator sling muscle, posterior urethrovesical angle, bladder neck descent, and levator plate angle. RESULTS: The 3 groups of subjects were comparable in age, parity, and body mass index. In the control, genuine stress incontinence, and prolapse groups, the menopausal rate was 40%, 60%, and 55% (P =.7). In the same order, significant mean 2-dimensional measures were: resting bladder neck descent of 24, 17, and 3 mm (P <.005), straining levator plate angle of -4.3, -11.5, and -31 degrees (P =.01), straining levator hiatus height of 48.5, 51.1, and 65.3 mm (P <.005), and straining perineal descent of 17.2, 22.5, 27.2 mm (P =.02). Similarly ordered mean 3-dimensional parameters showed levator volumes of 32.2, 23.3, and 18.4 cm(3) (P <.005); hiatus widths of 25.7, 34.7, and 40.3 mm (P <.005); left levator sling muscle gaps of 15.6, 20.3, and 23.8 mm (P =.03), right levator sling muscle gaps of 15.6, 22.5, and 30.8 mm, (P = 0.003), and levator shape (90%, 40%, and 20% dome shaped; P <.005). CONCLUSION: Both 2-dimensional magnetic resonance images and 3-dimensional models yield findings that differ among asymptomatic subjects compared with those with genuine stress incontinence and prolapse. Our 3-dimensional data demonstrate a statistically significant continuum in levator volume, shape, and integrity across groups of asymptomatic, genuine stress incontinence, and prolapse subjects.     

Evaluation of Aa point and cotton-tipped swab test as predictors of urodynamic stress incontinence

OBJECTIVE: To compare the predictive abilities of the Aa point of the pelvic organ prolapse quantification examination and the cotton-tipped swab test straining angle to diagnose urodynamic stress incontinence. METHODS: A case-control study was conducted between June 1997 and February 2003. Cases were defined as patients with urodynamic stress incontinence (n = 352). Controls were patients who also underwent urodynamic testing but who did not have a diagnosis of urodynamic stress incontinence (n = 245). Independent variables were defined as Aa point, Aa point of 0 or greater, straining cotton-tipped swab angle, and straining cotton-tipped swab angle of 30 degrees or greater. Logistic regression estimated the odds ratio of stress incontinence in women based on Aa values and cotton-tipped swab straining angle measurements, controlling for other variables commonly associated with stress incontinence. RESULTS: The mean (+/- standard deviation) age of the cases was 55.9 +/- 13.4 and of controls was 55.3 +/- 14.8, (P = .6). The median parity of the cases was 2 (range 0-10) and of controls, 2 (range 0-9) (P = .7). The Aa point was not associated with a diagnosis of stress incontinence (odds ratio 1.01, 95% confidence interval (CI) 0.83-1.23). The adjusted odds ratios of having an Aa value of 0 or greater was 0.49 (95% CI 0.26-0.92), and of having a cotton-tipped swab angle of 30 degrees or greater was 3.1 (95% CI 1.09-5.07), in a model that adjusted for age, parity, race, and postmenopausal and hormonal replacement status. CONCLUSION: Aa point is not associated with a diagnosis of stress incontinence. However, a cotton-tipped swab angle of 30 degrees or greater is positively associated with stress incontinence.     

Effect of laparoscopic hysterectomy on bladder neck and urinary symptoms

OBJECTIVE: To assess the effect of laparoscopic hysterectomy (LH) on the mobility and position of bladder neck (BN) and urinary symptoms. DESIGN: We assessed the BN and urinary symptoms of 151 patients by introital ultrasonography and questionnaires before and after LH. SAMPLE: One hundred and fifty-one women who underwent LH from June 1999 to June 2001. RESULTS: A significant decrease was noted in the number of women exhibiting one or more urinary symptoms from 81 (53.6%) preoperatively to 58 (38.4%) postoperatively (P < 0.01). The incidence of urinary frequency, mild stress incontinence and nocturia decreased significantly after laparoscopic hysterectomy (P < 0.01). Changes in other urinary symptoms following hysterectomy showed no statistical significance (P > 0.05). During straining, the postoperative position of the BN localised more dorsally (P < 0.01) and the ventral mobility of the BN decreased significantly following surgery (P < 0.05). There was no significant difference in the location of the BN with respect to the pubis at rest and during straining, in the cephalocaudal direction, before and after hysterectomy (P > 0.05). CONCLUSION: Some patients experienced a substantial improvement of preoperative urinary symptoms following LH, partly as a result of a decrease in the hypermobility of BN.     

Q-tip test: a study of continent and incontinent women

Urethral axis position and mobility, as determined by the "Q-tip test," were measured in subjectively continent women (N = 26), women with genuine stress incontinence (N = 28), and women with other types of urinary incontinence and voiding dysfunction (N = 20). Diagnostic urodynamic evaluation in symptomatic women included standard history, physical examination, urine culture, Q-tip test, uroflowmetry, standing "stress test," resting and stress urethral pressure profiles, and subtracted medium-fill water cystometry with provocation. Multiple regression analysis was used to determine the existence of significant clinical predictors of the dependent variables (stress angle, urethral mobility). These factors were used as covariates to identify differences between the adjusted group means. The results indicate a wide range of values for each Q-tip test measurement in all groups. Age, parity, resting Q-tip angle, and the presence of anterior vaginal relaxation were associated with maximum stress Q-tip measurement. Significant differences in maximum stress Q-tip angle and urethral mobility were noted only between the continent controls and women with genuine stress incontinence. No differences were found between the two incontinent study groups. We conclude that urethral position and mobility as measured by the Q-tip test are related to defects in anterior vaginal support, but not to specific urologic diagnosis.     

Urodynamic and clinical assessment of the Lyodura sling operation for urinary stress incontinence

A Lyodura sling operation for urinary stress incontinence was performed on 36 patients. The success rate was 89%, when success was defined as absence of objective urine loss at coughing or straining, with full bladder in the upright position and during a Urilos test, at least 6 months after surgery. Full urodynamic assessment, including urethral rest and stress profiles, were performed before, and 6 months after, surgery. Success of the operation depended mainly on enhancement of urethral pressure transmission. Functional length of the urethra and maximal urethral pressure did not influence the success rate. The procedure is especially suitable in patients with some degree of uterine or vaginal prolapse.     

Urodynamic and clinical assessment of the Lyodura sling operation for urinary stress incontinence

Summary. A Lyodura sling operation for urinary stress incontinence was performed on 36 patients. The success rate was 89%, when success was defined as absence of objective urine loss at coughing or straining. with full bladder in the upright position and during a Urilos test. at least 6 months after surgery. Full urodynamic assessment, including urethral rest and stress profiles, were performed before, and 6 months after, surgery. Success of the operation depended mainly on enhancement of urethral pressure transmission. Functional length of the urethra and maximal urethral pressure did not influence the success rate. The procedure is especially suitable in patients with some degree of uterine or vaginal prolapse.     

Urinary tract dysfunction after radical hysterectomy for cervical cancer

OBJECTIVES: To evaluate the urinary tract dysfunction following a radical hysterectomy and to compare the baseline urodynamical parameters of women who had uterine cervical carcinoma with women who had CIN 3. METHODS: A prospective case-control study was conducted to evaluate preoperative and postoperative urinary tract function of thirty-two cervical carcinoma patients using twenty-seven CIN 3 patients' preoperative urodynamical parameters as a baseline control. RESULTS: The rate of detrusor instability in women with preoperative cervical carcinoma was higher than that of women with CIN 3 (37.5 % vs. 14.8 %, P < 0.05). In the cervical carcinoma patients, there were 53.1 % who had normal urinary tract function, but after a radical hysterectomy they began voiding by abdominal straining. The impairment of bladder sensation, alteration of bladder capacity and bladder compliance, compromise of detrusor function, reduction of maximal urethral pressure and maximal urethral closure pressure, and the decrease of the pressure transmission ratio were significantly noted after a radical hysterectomy. The rate of genuine stress incontinence did not increase significantly (9.4 % vs. 18.8%, P > 0.05), but the rate of detrusor instability decreased significantly (37.5% vs. 15.6%, P < 0.05) after a radical hysterectomy. CONCLUSIONS: Changes of urinary tract function after a radical hysterectomy might be related to the partial sympathetic and parasympathetic denervation during a radical dissection. More than half of the women who preoperatively had normal urinary tract function needed to void by abdominal straining after radical surgery.     

不同路径阴道无张力尿道中段悬吊术治疗重度压力性尿失禁

目的 探讨经耻骨后路径阴道无张力尿道中段悬吊(TVT)术及经闭孔路径阴道无张力尿道中段悬吊(TVT-O)术治疗女性重度压力性尿失禁的临床效果.方法 前瞻性随机对照单盲方法选取重度压力性尿失禁患者69例(其中35例行TVT,34例行TVT-O),部分患者合并Ⅰ～Ⅱ度子宫脱垂及阴道前壁膨出.分别记录两种路径手术的手术时间、术中出血量、术后住院时间、住院费用,以及术中、术后并发症的类型和发生率.运用尿道疾病程度分类问卷(UDI-6)和尿失禁相关生活质量问卷(ⅡQ-7)对两组患者组内及组间手术前后生活质量的变化进行评估.结果 TVT-O组平均手术时间为(18±5)min,明显短于TVT组的(27±5)min,差异有统计学意义(P＜0.01).两组术中出血量、术后第1天B超测量残余尿量的合格率、并发症发生率、术后住院时间和住院费用均相似,差异均无统计学意义(P均＞0.05).术后随访率100%,平均随访时间14.5个月.TVT组治愈率88.6%(31/35),略高于TVT-O组[85.3%(29/34)],但两组间比较,差异无统计学意义(P＞0.05).吊带侵蚀发生率TVT组为5.7%(2/35),高于TVT-O组[2.9%(1/34)];耻骨上、腹股沟或大腿内侧酸痛发生率TVT组为5.7%(2/35),低于TVT-O组[14.7%(5/34)],但差异均无统计学意义(P均＞0.05).两组间手术前后UDI-6和ⅡQ-7问卷各项目评分及总体评分分别比较,差异均无统计学意义(P均＞0.05).两组内手术后UDI-6问卷(除梗阻项目)和ⅡQ-7问卷各项目评分及总体评分较手术前均明显降低,差异均有统计学意义(P均＜0.01),UDI-6问卷中梗阻项目评分,两组内手术前后比较,差异无统计学意义(P＞0.05).结论 TVT-O路径较TVT路径手术时间短,术后短期随访结果显示,两种手术路径均可有效治疗重度压力性尿失禁、改善患者生活质量且不增加尿道梗阻风险,但长期疗效有待进一步随访观察.     

Computer-assisted virtual urethral pressure profile in the assessment of female genuine stress incontinence.

OBJECTIVE: To compare computer-assisted virtual urethral pressure profile changes between women with and without genuine stress incontinence. METHODS: A full urogynecologic assessment including conventional urodynamic measurements and a clinical stress test were carried out. Computer-assisted virtual urethral pressure profile uses conventional urethral pressure profile measurements during stress, with the only change being that withdrawal of the catheter is stopped at distinct points along the whole urethra while the patient coughs. Cough-related changes of maximal urethral closure pressure, functional urethral length, and area under the urethral closure pressure curve were determined. RESULTS: Sixty-one women were enrolled in our study: 30 symptom-free women (group A) were continent, and genuine stress incontinence was present in 31 patients (group B) complaining of urinary loss. Significant differences between group A and group B women were found for all parameters of computer-assisted virtual urethral pressure profile including maximal urethral closure pressure (91.59 +/- 39.00 versus 20.70 +/- 22.61 cm H(2)O; P <.001), functional urethral length (31.81 +/- 9.02 versus 10.83 +/- 10.76 mm; P <.001), and the area under the urethral closure pressure curve (2036 +/- 1025.29 versus 253 +/- 206.69 cm H(2)O x mm; P <.001). CONCLUSION: Computer-assisted virtual urethral pressure profile is a new application of urethral pressure profile measurements during stress. Our data show significant differences between continent women and patients with genuine stress incontinence. Further studies are needed to assess the potential of computer-assisted virtual urethral pressure profile for diagnosing genuine stress incontinence.     

Influence of catheterisation on the results of sonographic urethrocystography in patients with genuine stress incontinence

Using introital sonography as an alternative to lateral chain urethrocystography during urodynamic studies, a prospective investigation was carried out in 47 patients with lower urinary tract complaints, to determine the correlation of sonographic assessment with and without bladder catheterisation. The apparent location of the bladder neck in relation to the pubic symphysis and measurements of the posterior urethrovesical angle at rest and during straining during cystometry with and without intravesical urodynamic pressure transducers were determined. In 22 (46.8%) patients the bladder neck at rest was below the lower edge of the symphysis. This finding was not influenced by the presence of a catheter. Correlation coefficients (r) for posterior urethrovesical angles at rest and during straining measured with and without catheters were 0.95 (95% confidence limits 0.92–0.98;P<0.01) and 0.98 (95% confidence limits 0.96–0.99;P<0.01), respectively. The coefficients of determination (r ²) at rest and during straining were 0.92 and 0.95, respectively. Sonography with and without cystometry equipment in place gave similar results.     

Comparison of transobturator tape (TOT) and tension-free vaginal tape (TVT) using perineal ultrasound

OBJECTIVE: Using perineal ultrasound in two groups of patients having either TVT or TOT procedure to know if TOT is sufficiently oblique and if the large dissection in TOT procedure might be responsible for migration of the tape. PATIENTS AND METHODS: Thirty-two patients, 16 TVT and 16 TOT, had a sonography. The tape is visualised in the sagittal and frontal planes at rest, maximum holding and valsalva straining. The angle between the two limbs of the tape is measured as well as the distance tape-bladder neck and the width of the tape. RESULTS: The aspect of the tape at rest is like a V, in both groups. During straining, the urethra is flattened on the tape which becomes round. During maximum retaining, the V closes by traction on the limbs. The mean angle under the urethra at rest is 109.9 degrees. In the TVT group it is 101.6 degrees versus 118.1 degrees in the TOT group. This difference is statistically significant (P=0.001). The width of the tape is 6.7 mm (2.4-10.3). The distance tape-bladder neck is 14.8 mm (8.2-25.7), 14.6 mm for the TVT group and 15.6 mm for the TOT group, the mean urethral length being 33.1 mm. DISCUSSION AND CONCLUSION: The angle of TOT is more open. It remains sufficiently oblique and allows the tape to be put with light tension if needed in low-pressure urethra. In spite of larger urethrovaginal dissection in TOT, the tape does not migrate close to the bladder neck and remains at mid-urethra.