Sonographic Evaluation of Anatomic Results After the Pubovaginal Sling Procedure for Stress Urinary Incontinence

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1 Article Sonographic Evaluation of Anatomic Results After the Pubovaginal Sling Procedure for Stress Urinary Incontinence Hann-Chorng Kuo, MD Objective. To investigate the anatomic changes after the pubovaginal sling procedure in women with stress urinary incontinence by transrectal sonography. Methods. This study enrolled 56 women with varying types of stress urinary incontinence who were treated with the pubovaginal sling procedure using self-fashioned polypropylene mesh. The suburethral sling was fixed without tension and was placed at the position between the bladder neck and the proximal urethra. The patients were investigated preoperatively and postoperatively by transrectal sonography of the bladder and urethra. Results. At a median follow-up of 24 months (range, 6 39 months), 48 patients (85.7%) were cured, 6 (10.7%) had improved, and 2 (3.6%) had treatment failures. Transrectal sonography revealed a wellsuspended bladder neck and proximal urethra in all patients who were cured. As measured by changes of the axis of the pubovesical ligament, the position of the bladder neck was elevated by a mean of 29.6 ± 21.5 in the resting condition and 47.4 ± 27.7 in the straining condition. An incompetent bladder neck and proximal urethra were noted in 8 patients who had stress urinary incontinence after surgery. The incidence of opening of the bladder neck was 84.6% in 13 patients with de novo urgency or urge incontinence, whereas only 2 (4.7%) of 43 patients who did not have postoperative urgency had opening of the neck (P =.000). Conclusion. Transrectal sonography provides useful information about anatomic changes after the pubovaginal sling procedure. Bladder neck incompetence after surgery was closely related to postoperative urgency or urge incontinence. Key words: transrectal sonography; stress incontinence; urethral anatomy. Abbreviations ISD, intrinsic sphincteric deficiency; SUI, stress urinary incontinence; VLPP, Valsalva leak point pressure Received November 28, 2000, from the Department of Urology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan, Republic of China. Revision requested February 27, Revised manuscript accepted for publication March 26, This study was supported by a grant from the National Science Council of the Republic of China (NSC B ). Address correspondence and reprint requests to Hann-Chorng Kuo, MD, Department of Urology, Buddhist Tzu Chi General Hospital, 707, Section 3, Chung Yang Road, Hualien, Taiwan, Republic of China. The pubovaginal sling procedure is a wellestablished surgical procedure for all types of female stress urinary incontinence (SUI). This procedure provides an excellent success rate and minimal surgical morbidity. 1 3 However, a few patients might have persistent SUI, and some have de novo urgency or urge incontinence after surgery. 4 6 Among the patients with surgical failure, bladder outlet obstruction is the most common cause of failure, especially in patients who have an acontractile bladder due to previous radical hysterectomy or large cystocele. 7 9 In patients with increased urethral resistance after the pubovaginal sling procedure, de novo urgency or urge incontinence might develop. 10, by the American Institute of Ultrasound in Medicine J Ultrasound Med 20: , /01/$3.50

2 Anatomic Results After the Pubovaginal Sling Procedure A video urodynamic study is a useful investigative tool for assessing lower urinary tract function after the pubovaginal sling procedure, 12 but transrectal sonography of the bladder and urethra provides an excellent window for viewing the anatomic changes of the urethra and the position of the bladder neck after surgery. 13 This study was conducted to investigate the anatomic findings on transrectal sonography of the lower urinary tract after the pubovaginal sling procedure. Materials and Methods From July 1997 to June 2000, 56 consecutive women with various types of SUI who were treated with the pubovaginal sling procedure were investigated preoperatively and postoperatively by transrectal sonography of the bladder and urethra. All patients were routinely investigated by a video urodynamic study, and types of SUI were classified according to Valsalva leak point pressures (VLPPs). Type 2 SUI was diagnosed if the VLPP was greater than 90 cm H 2 O. Type 3 SUI was diagnosed if the VLPP was less than 60 cm H 2 O. A combination of types 2 and 3 SUI was diagnosed if the VLPP was 60 to 90 cm H 2 O. 4,14 Hypermobility of the bladder base was classified as no hypermobility, mild hypermobility (bladder neck descent of <2 cm on exertion), moderate hypermobility (>2 cm descent), and cystocele during the video urodynamic study. The degrees of cystocele were defined according to the classification of 5 stages of pelvic organ support. 15 Patients who had previously undergone radical hysterectomy or who had a nonfunctioning urethra or noncontractile detrusor were not excluded from the study. The surgical procedure of the pubovaginal sling has been published previously. 16 The sling was created by cutting a piece of cm polypropylene mesh (Ethicon Company, Edinburgh, Scotland) into 15 strips, each measuring 30 2 cm. The slings were prepared in advance for treatment of SUI. For the patients with type 3 SUI or without bladder base hypermobility, the sling was suspended without further tension. For those with type 2 SUI or with bladder base hypermobility, the sling was suspended with sufficient tension to restore the bladder neck to the retropubic position. Concomitant vaginal hysterectomy was performed in the patient who had uterine prolapse, and anterior colporrhaphy was performed in those patients with cystocele of grade 3 or higher before placement of the pubovaginal sling. The patients were investigated preoperatively and postoperatively by transrectal sonography of the bladder and urethra. The transrectal sonography was performed by a senior technician who did not know the postoperative conditions of the examinees, and the interpreter was blinded to the postoperative symptoms of the patients. During transrectal sonography, the patients were examined in the standing position with legs 1 ft apart and facing the monitor, and the examiner was sitting behind them. A 7-MHz multiplanar transrectal probe (model 8551; Brüel & Kjær, Nærum, Denmark) was used to investigate the bladder neck and urethra in the sagittal and transverse planes. At first, the bladder and urethra were scanned thoroughly for detection of any lower urinary tract lesions. The scanning plane was turned to the sagittal view, and the urethral axis was identified. In the sagittal view, the urethral lumen and surrounding smooth and striated muscles could be found by identifying the bladder neck and tracing to the urethral lumen at the midline (Fig. 1). In a competent urethra, the urethral lumen appeared to be a condensed line; however, in an incompetent urethra, the urethra appeared to have 2 lines representing the opening lumen (Fig. 2). Next, the scanning plane was turned to the transverse view at the midurethra, and the cross section of the urethra was investigated. The position of the bladder neck was measured with a reference marker at the lower margin of the symphysis pubis. The angle of the axis of the pubovesical ligament (connection between the symphysis pubis and the bladder neck) to the transverse axis of the reference marker was considered to be the bladder neck position (Fig. 1). During abdominal straining, the changes in the axis of the pubovesical ligament and sling position were recorded. The measurements of transrectal sonographic findings have been described in previous reports. 17,18 The width of the sling was measured in the sagittal section of the midline of the urethral axis. The distance between the sling and the bladder neck was measured along the urethral axis in the sagittal section. The distance between the sling and the urethra was measured in the transverse section of the midurethra as illustrated in Figure 1. These sonographic parameters were compared in all patients between the time before surgery and the third postoperative month. 740 J Ultrasound Med 20: , 2001

3 Kuo In the patients who had persistent SUI and the patients who had de novo urgency or urge incontinence, the sonographic findings of the urethra were compared with those in the patients who were cured and free of urgency. The sonographic features were focused on the location of the sling, bladder neck incompetence during the straining condition, and urethral incompetence during resting and straining conditions. Figure 1. Transrectal sonography of the bladder and urethra after the pubovaginal sling procedure using a polypropylene mesh. A, In the sagittal section, the sling was placed at the proximal suburethral region, and the bladder neck was well suspended and competent. The width of the sling (W) and the distance between the sling and the bladder neck could be measured (D). The bladder neck position was measured by the angle of the pubovesical ligament (PVL Angle). B, In the transverse section, the midurethra was supported by the sling, and there was adequate thickness of the endopelvic fascia between the urethra and the sling (T, between the dashed lines) so that the urethra was not directly compressed by the sling. A B J Ultrasound Med 20: ,

4 Anatomic Results After the Pubovaginal Sling Procedure A B Figure 2. Transvaginal urethrolysis was performed in a patient with an acontractile detrusor and ISD who had dysuria after the sling procedure. A, Posturethrolysis sonography, sagittal section. The urethra became incompetent during straining, although the bladder neck remained well suspended. B, Posturethrolysis sonography, transverse section. An incompetent urethra was clearly visible, whereas the underlying sling (between the bottom arrows) remained in place. Statistical analysis was performed with the Student paired t test for the paired urodynamic and sonographic parameters. The Mann- Whitney rank sum test was used to compare the sonographic findings among the patients with different types of SUI. P <.05 was considered statistically significant. Results The mean age was 60.3 ± 11.2 years (range, years), and mean parity was 3.5 ± 2.3 (range, 2 7). There were 5 women who had had radical hysterectomy for cervical malignancy, 17 women who had had previous abdominal total hysterectomy for benign uterine lesions, and 3 women who had had previous anti-incontinence surgery. According to the preoperative assessment, 28 patients had type 2 SUI, 11 had a combination of types 2 and 3 SUI, and 17 had type 3 SUI. Grade 3 cystocele was found in 3 patients, and uterine prolapse was noted in 1 patient. At a median follow-up of 24 months (range, 6 39 months), complete continence was reported by 48 patients (85.7%), mild SUI without the need for pad protection was reported in 6 patients (10.7%), and persistent SUI was reported in 2 patients (3.6%). The postoperative results and symptoms are listed in Table 1. Postoperatively, persistent urge incontinence was found in 3 patients, de novo urge incontinence was found in 5, and de novo urgency without incontinence was found in 5. Two patients with type 2 SUI had persistent SUI 1 month after surgery, and video urodynamic studies revealed the existence of an intrinsic sphincteric deficiency (ISD). A second polypropylene sling was applied distal to the first one, and that cured their SUI. The total success rate was 96.3% at the final visit, including the 2 patients who underwent the second sling procedure during the first postoperative month. Transrectal sonography of the bladder and urethra revealed a well-suspended bladder neck and proximal urethra in all patients who were cured. There was an endopelvic fascia space between the sling and the urethra, and the urethral lumen was closed during resting and straining conditions (Fig. 1A). By the third postoperative month, the mean sling width was 12.5 ± 3.5 mm (range, mm). As measured by changes of the axis of the pubovesical ligament, the postoperative bladder neck position was elevated by a mean of 29.6 ± 21.5 in the resting condition (57.3 ± 27.1 at baseline versus postoperatively; P =.000) and 47.4 ± 27.7 in the straining condition (75.1 ± 39.5 at baseline versus 27.7 ± 7.9 postoperatively; P =.000). In the transverse section, the thickness of the endopelvic fascia 742 J Ultrasound Med 20: , 2001

5 Kuo between the sling and the urethra was thicker in the patients with type 2 SUI than in those with type 3 SUI (5.3 ± 1.5 versus 3.3 ± 1.3 mm; P =.001). In the sagittal section, the sling was located at the level of the bladder neck and proximal urethra (Fig. 1A). The mean distance from bladder neck to sling was 3.3 ± 2.7 mm (range, mm). No remarkable urethral kinking was found while performing Valsalva s maneuver or vigorous coughs. There was no significant movement of the bladder neck on exertion. The sonographic measurements in different types of SUI are listed in Table 2. There were no differences in the sonographic measurements among the patients with the 3 types of SUI except the endopelvic fascia thickness between the patients with type 2 and type 3 SUI. When the patients who had had previous hysterectomy or anti-incontinence surgery were compared with those who had not, there was also no significant difference in the postoperative sonographic measurements. In the 2 patients who had persistent moderate SUI after urethrolysis, sonography showed a remarkable incompetent bladder neck and proximal urethra (Fig. 2). There was a hypoechoic space between urethral mucosa during straining, indicating an incompetent bladder outlet. However, the bladder base remained elevated with little mobility during coughs, indicating that the bladder base was well suspended. In the 6 patients who had mild SUI after the sling procedure, postoperative transrectal sonography showed an incompetent bladder neck and proximal urethra on both sagittal and transverse scans (Fig. 3). In video urodynamic studies, the mean leak point pressure in these 6 patients was 105 ± 27.5 cm H 2 O (range, cm H 2 O), which was significantly higher than that of the baseline (mean, 55.4 ± 13.7 cm H 2 O; P =.000). In the 13 patients with postoperative urgency (n = 5) and urge incontinence (n = 8), 5 with a combination of types 2 and 3 SUI and 6 patients with type 3 SUI had an open bladder neck during abdominal straining (Fig. 4). The incidence of opening of the bladder neck was 84.6% in these patients with urgency or urge incontinence. However, in the 43 patients who did not have postoperative urgency or urge incontinence, only 2 patients (4.7%) had an open bladder neck; the difference was highly significant (P =.000). Table 1. Results of the Pubovaginal Sling Procedure in Patients With SUI Results, n (%) Postoperative Status No. of Patients Cured, 48 (85.7) Complete continence 43 on exertion De novo urgency 5 without incontinence Mild stress Mild stress incontinence 6 incontinence, 6 (10.7) (<50% of preoperative symptoms) Persistent urge incontinence 2 De novo urge incontinence 4 Persistent stress Moderate stress incontinence 2 incontinence, 2 (3.6) (>50% of preoperative symptoms) Persistent urge incontinence 1 De novo urge incontinence 1 Discussion The results of this study show that the transrectal sonographic findings after the pubovaginal sling procedure can correlate well with postoperative functional results. An open bladder neck after the pubovaginal sling procedure may result in persistent urgency or de novo detrusor instability. An open bladder neck was found in 84.6% of patients who had postoperative urgency or urge incontinence, whereas it was found in only 4.7% of patients who had been cured and were free of urgency. In the patients who had a persistent open bladder neck after the pubovaginal sling procedure, the sling was located below the urethra but not the bladder neck so that the bladder neck was not adequately supported and closed. Table 2. Changes in Sonographic Parameters After the Pubovaginal Sling Procedure in 3 Types of Stress Incontinence Type 2/3 Sonographic Type 2 SUI Combination SUI Type 3 SUI Parameter (n = 28) (n = 11) (n = 17) P Postoperative BN 29.3 ± ± ± 12.7 >.05 position (angle of PVL axis), Changes of BN 1.5 ± ± ± 1.5 >.05 position on straining, Sling width, mm 12.3 ± ± ± 2.3 >.05 Distance between 3.5 ± ± ± 2.9 >.05 sling and BN, mm Endopelvic fascia 5.3 ± ± ± 1.3 <.001 thickness, mm type 2 vs 3 BN indicates bladder neck; and PVL, pubovesical ligament. J Ultrasound Med 20: ,

6 Anatomic Results After the Pubovaginal Sling Procedure A Figure 3. A, Incompetent urethra clearly shown in a patient who had mild stress incontinence after the pubovaginal sling procedure. B, Competent urethra after surgery, shown for comparison. In the incompetent urethra, there was a space between the urethral mucosa, and the distance between the urethra and sling (between the 2 dashed lines) was large, indicating that the urethra was not adequately compressed. In the competent urethra, the urethral lumen was condensed without a remarkable space between the urethral mucosa. B Figure 4. A, Preoperative bladder neck incompetence and urethral hypermobility. B, Incompetent bladder neck after the pubovaginal sling procedure in a patient who had postoperative urgency with a full bladder. A B 744 J Ultrasound Med 20: , 2001

7 Kuo Transrectal sonography of the bladder and urethra provides a clear anatomic window to lower urinary tract dysfunction in SUI and frequencyurgency syndrome. 13,18 Previous studies have shown that the cross-sectional area decreased in patients with SUI compared with that in women without SUI. The thickness of the urethropelvic ligament also decreased in women with SUI. 13 Although frequency-urgency syndrome may have several causes responsible for patients symptoms, an incompetent bladder neck has been found to be associated with hypermobility of the bladder neck in both asymptomatic women and women with frequency-urgency syndrome. 18 The pubovaginal sling procedure using either autologous fascia or synthetic material has gained popularity in recent years to treat all types of SUI. 1 5,19,20 However, the incidence of de novo detrusor instability remains a problem to be solved. In the classic pubovaginal sling procedure, Chaikin et al 3 and Cross et al 4 addressed the idea that the sling should be tied with minimal tension at the bladder neck to prevent iatrogenic bladder outlet obstruction. 3,4 Recently, a tensionfree vaginal tape was developed that was placed at the midurethra without tension. That procedure has had a high success rate and low surgical morbidity and has been widely accepted as the treatment of choice for SUI My procedure has adopted the working effects of the classic pubovaginal sling and tension-free vaginal tape. With fixation of the 4 corners at either side of the bladder neck, the bladder neck and proximal urethra can be suspended to a high retropubic position without direct compression of the urethra proper. A fairly thick endopelvic fascia between the sling and urethra can act as a buffer to prevent bladder outlet obstruction after surgery. The good surgical results confirmed this cushion effect, but some patients with ISD might have persistent mild SUI after surgery because of inadequate urethral compression. With the use of transrectal sonography of the bladder and urethra, the anatomic changes after the pubovaginal sling procedure as well as the location of the suburethral sling could be clearly seen. An incompetent bladder neck and urethra were associated with persistent mild SUI. An incompetent bladder neck after surgery was associated with postoperative urgency or urge incontinence, whereas a closed bladder neck was not. A second sling at the distal urethra could cure the ISD that was not completely corrected by the first sling at the proximal urethra. A thicker endopelvic fascia between the sling and the urethra could prevent bladder outlet obstruction after the pubovaginal sling procedure. These sonographic findings are valuable in evaluation of postoperative lower urinary tract dysfunction in women with SUI. Moreover, the rationale has been to suspend the bladder neck adequately in patients who have been found to have an open bladder neck and detrusor instability preoperatively. During the pubovaginal sling procedure, a surgeon can apply the pubovaginal sling more precisely beneath the open bladder neck and can close the bladder neck adequately to prevent postoperative urgency or urge incontinence. Postoperatively, when an incompetent urethra is found to be associated with persistent stress incontinence by transrectal sonography, a second pubovaginal sling can be applied to the urethra to cure the incontinence. Although an incompetent bladder neck may appear in nulliparous women without SUI, 24 the presence of an incompetent bladder neck has been found to be associated with higher bladder neck hypermobility in women with frequencyurgency syndrome and asymptomatic women. 18 Defects in the extrinsic continence mechanism may affect both bladder neck closure and urethral stability. Through the urethral detrusor facilitative reflex, an open bladder neck might induce unstable detrusor contraction or urge sensation during the straining condition. 25 If the bladder neck can be closed concomitantly during the pubovaginal sling procedure, the postoperative urgency or urge incontinence might disappear, as observed previously in patients with mixed incontinence who underwent colposuspension. 26 In some women with a nonfunctioning urethra and an acontractile detrusor, the sling cannot be tied very tightly, and the position of the bladder neck has to be elevated to a certain degree. In these patients, an incompletely closed bladder neck and urethra may result in residual mild SUI. When transrectal sonography is performed during the straining condition, urine will fill in the urethra and the urethral lumen will become visible. When a second sling is placed at the distal urethra, SUI can be cured, but an incompetent proximal urethra might still exist. Transrectal sonography is a useful tool for investigating the incompetent urethra after the pubovaginal sling procedure and provides anatomic evidence for a further surgical correction. J Ultrasound Med 20: ,

8 Anatomic Results After the Pubovaginal Sling Procedure Conclusions Anatomic assessment of SUI before undertaking corrective surgery is essential. Understanding the anatomic defects of urethral muscles and the extrinsic continence mechanism makes it possible to choose a precise surgical procedure. When an incompetent urethra is shown on transrectal sonography before surgery, a sling of adequate tension at the urethra may be necessary to achieve a competent urethra after surgery. Leaving an incompetent bladder neck might result in postoperative urgency or urge incontinence, whereas leaving an incompetent urethra might result in inadequate correction of SUI. However, the detrusor contractility should also be considered; in patients with very low detrusor contractility, the tension of the sling must be a little lower than that in women who have normal detrusor contractility. A video urodynamic study provides functional information about the bladder and urethra, whereas sonography provides anatomic information. These 2 investigative tools are of equal importance for a successful surgical result. References 1. Morgan TO, Westney OL, McGuire EJ. Pubovaginal sling: 4-year outcome analysis and quality of life assessment. J Urol 2000; 163: Hassouna M, Ghoniem GM. Long-term outcome and quality of life after modified pubovaginal sling for intrinsic sphincteric deficiency. Urology 1999; 53: Chaikin DC, Blaivas JG, Rosenthal JE, et al. Results of pubovaginal sling for stress incontinence: a prospective comparison of 4 instruments for outcome analysis. J Urol 1999; 162: Cross CA, Cespedes RD, McGuire EJ. Our experience with pubovaginal slings in patients with stress urinary incontinence. J Urol 1998; 159: Zaragoza MR. Expanded indications for the pubovaginal sling: treatment of type 2 or 3 stress incontinence. J Urol 1996; 156: Kelly MJ, Zimmern PE, Leach GE. Complications of bladder neck suspension procedure. Urol Clin North Am 1991; 18: Hilton P. A clinical and urodynamic study comparing the Stamey bladder neck suspension and suburethral sling procedure in the treatment of genuine stress incontinence. Br J Obstet Gynecol 1989; 96: Lose G, Jorgensen L, Mortensen SO, et al. Voiding difficulties after colposuspension. Obstet Gynecol 1987; 69: Walter S, Olesen KP, Hald T, et al. Urodynamic evaluation after vaginal repair and colposuspension. Br J Urol 1982; 81: Fulford SC, Flynn R, Barrington J, et al. An assessment of the surgical outcome and urodynamic effects of the pubovaginal sling for stress incontinence and the associated urge syndrome. J Urol 1999; 162: Klutke JJ, Klutke CG, Bergman J, et al. Urodynamic changes in voiding after anti-incontinence surgery: an insight into the mechanism of cure. Urology 1999; 54: Kuo HC. Videourodynamic results after pubovaginal sling procedure for stress urinary incontinence. Urology 1999; 54: Kuo HC. Transrectal sonography of the female urethra in incontinence and frequency-urgency syndrome. J Ultrasound Med 1996; 15: McGuire EJ, Fitzpatrick CC, Wan J, et al. Clinical assessment of urethral sphincter function. J Urol 1993; 150: Bump RC, Mattiasson A, Bo K, et al. The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction. Am J Obstet Gynecol 1996; 175: Kuo HC. Comparison of the surgical results of pubovaginal sling procedure using rectus fascia or polypropylene mesh. J Urol 2001; 165: Kuo HC, Chang SC, Hsu T. Application of transrectal sonography in the diagnosis and treatment of female stress urinary incontinence. Eur Urol 1994; 26: Kuo HC. Transrectal sonographic investigation of urethral and paraurethral structures in women with stress urinary incontinence. J Ultrasound Med 1998; 17: J Ultrasound Med 20: , 2001

9 Kuo 19. Chin YK, Stanton SL. A follow-up of Silastic sling for genuine stress incontinence. Br J Obstet Gynecol 1995; 102: Hom D, Desautel MG, Lumerman JH, et al. Pubovaginal sling using polypropylene mesh and vesica bone anchors. Urology 1998; 51: Olsson I, Kroon U. A three-year postoperative evaluation of tension-free vaginal tape. Gynecol Obstet Invest 1999; 48: Ulmsten U, Johnson P, Rezapour M. A three-year follow-up of tension free vaginal tape for surgical treatment of female stress urinary incontinence. Br J Obstet Gynecol 1999; 106: Ulmsten U, Falconer C, Johnson P, et al. A multicenter study of tension-free vaginal tape (TVT) for surgical treatment of stress urinary incontinence. Int Urogynecol J Pelvic Floor Dysfunct 1998; 9: Chapple CR, Helm CW, Blease S, et al. Asymptomatic bladder neck incompetence in nulliparous females. Br J Urol 1989; 64: Hindmarsk JR, Gosling PT, Deane AM. Bladder instability. Is the primary defect in the urethra? Br J Urol 1983; 55: Langer R, Ron-El R, Bukovsky I, et al. Colposuspension in patients with combined stress incontinence and detrusor instability. Eur Urol 1988; 14: J Ultrasound Med 20: ,