Incidence and Risk Factors of Postoperative De Novo Voiding Dysfunction following Midurethral Sling Procedures

Incidence and Risk Factors of Postoperative De Novo Voiding Dysfunction following Midurethral Sling Procedures Hoon Ah Jang, Jae Hyun Bae, Jeong Gu Lee From the Department of Urology, College of Medicine, Korea University, Seoul, Korea Purpose: To compare the incidence of postoperative de novo voiding dysfunction and to identify the risk factors affecting the development of de novo voiding dysfunction after various midurethral sling (MUS) procedures for female stress urinary incontinence (SUI). Materials and Methods: Women with SUI underwent MUS by various procedures [tension-free vaginal tape (TVT R ), tension-free vaginal tape obturator (TVTO R ), tension-free obturator tape (TOT R ), or TVT-secure R ]. Cases were reviewed retrospectively with follow-up of at least 6 months. The subjects were divided into 2 groups according to the presence of postoperative de novo voiding dysfunction. De novo voiding dysfunction was defined as a low maximal uroflow rate (Qmax<15 ml/s) or a large post-voided residual urine volume (PVR>100 ml) observed at 6 months postoperatively. Clinical and urodynamic parameters were compared between the voiding dysfunction (Group I) and normal voiding (Group II) groups according to MUS procedure. Results: Of the 625 subjects, 163 (26%) patients showed evidence of de novo voiding dysfunction (Group I). Of these 163 subjects, 12 (7.3%) patients complained of voiding symptoms. There was no difference in the incidence of de novo voiding dysfunction according to MUS procedure. Multivariate analysis showed Qmax to be the only independent risk factor for de novo voiding dysfunction. Conclusions: This study confirmed the considerable incidence of postoperative de novo voiding dysfunction, which is, however, mostly asymptomatic. As preoperative Qmax decreased, the chance of postoperative de novo voiding dysfunction increased. Identification of risk factors of voiding dysfunction in women undergoing MUS may help in planning for better follow-up and early detection of possibly inherent late complications of voiding dysfunction. (Korean J Urol 2009;50:762-766) Key Words: Urinary bladder, Complications Korean Journal of Urology Vol. 50 No. 8: 762-766, August 2009 DOI: 10.4111/kju.2009.50.8.762 Received:April 15, 2009 Accepted:July 22, 2009 Correspondence to: Jeong Gu Lee Department of Urology, Korea University Anam Hospital, 126-1, 5-ga, Anam-dong, Sungbuk-gu, Seoul 136-705, Korea TEL: 02-920-5683 FAX: 02-928-7864 E-mail: jeongkl@kumc.or.kr C The Korean Urological Association, 2009 INTRODUCTION The midurethral sling (MUS) procedure became one of the standard minimally invasive procedures used to treat stress urinary incontinence (SUI) since tension-free vaginal tape (TVT R ) was first described in 1996 by Ulmsten. 1-4 Shortly thereafter, a different method of tape insertion was described, in which the tape passes through the obturator foramen (transobturator tape, or TOT R ). Several variations of this method have been introduced to reduce complications such as bladder perforation. 5 In MUS, the sling provides dynamic kinking of the urethra when abdominal pressures increase but not at the resting phase. Thus, theoretically, MUS does not cause voiding dysfunction such as weak stream, urinary hesitancy, and straining voiding in itself. However, voiding dysfunction such as a decreased maximal uroflow rate (Qmax) or increased post-voided residual urine volume (PVR) has been reported after the MUS operation. 3,6 762

Hoon Ah Jang, et al:incidence and Risk Factors of Postop. Voiding Dysfunction following MUS 763 Although a standard definition of female voiding dysfunction is controversial, 7 Qmax, PVR, and voiding time are used as criteria for voiding dysfunction. 3,8,9 The incidence of voiding dysfunction after MUS has been reported to be between 4% and 55% and it may affect the patient s well-being and quality of life (QoL), consequently decreasing patient satisfaction with the procedure. 2,3,10 Postoperative voiding dysfunction can be self-limiting if urinary symptoms do not exist and the PVR is adequate. 1,11 However, in some severe cases, unavoidable removal or relaxation of the mesh has been reported. 12,13 The incidence and risk factors of de novo voiding dysfunction after the MUS procedure in patients with normal voiding function preoperatively have yet to be evaluated. The aim of the present study was therefore to evaluate the incidence and risk factors of de novo voiding dysfunction after the MUS procedure and to compare these according to type of MUS device. MATERIALS AND METHODS Between 2004 and 2008, the medical records of patients who underwent MUS for treatment of SUI utilizing various procedures (TVT R, TVTO R, TOT R, and TVT-secure R ) with at least 6 months of follow-up were reviewed retrospectively. To exclude preoperative voiding difficulties overlapping the criteria of de novo voiding dysfunction, patients with preoperative Qmax less than 15 ml/s or PVR>100 ml were excluded. Patients who showed an obstructive pattern on preoperative uroflowmetry or who had postoperative retention were also excluded from the study. Voiding dysfunction after MUS was defined when more than one of the following was observed: 1) de novo postoperative voiding symptoms (such as frequency, weak stream, voiding difficulty, and residual sensation), 2) obstructive pattern on uroflowmetry, 3) postoperative Qmax<15 ml/s, 4) residual urine volume>100 ml. The study population was divided into 2 groups, one with postoperative de novo voiding dysfunction (group 1) and the other with normal voiding after MUS (group 2). The criterion of Qmax<15 ml/s as a cutoff value for voiding dysfunction was based on the female voiding dysfunction guideline published by the Korean Continence Society. 14 Preoperative evaluation of all patients included age, history taking, physical examination, body mass index (BMI), parity, voiding diary, Bristol female lower urinary tract symptom (LUTS) questionnaire (BF-LUTS), and urodynamic studies including Qmax, PVR, and detrusor pressure at the maximum flow rate (Pdetmax). Preoperative SUI symptoms were classified by Stamey grade. 15 Postoperative evaluation was done at 3 and 6 months after the MUS procedure. All patients were followed up with voiding symptom history, physical examination, uroflowmetry, voiding diary, and a validated questionnaire to assess the patient s perception of the results of and satisfaction with the surgery. Cure of SUI was defined as complete dry and improvement as still urine leakage but no treatment required or patient satisfied with the results of the operation. Cure and improvement were regarded as successful treatment of SUI. Independent-sample t-tests and Pearson's chi-square test were used to test the statistical significance of differences between patients with and without postoperative voiding dysfunction. Logistic regression analysis was used to explore the risk factors of postoperative Qmax decrease. Statistical significance was considered at p<0.05. RESULTS A total of 631 patients underwent the MUS procedure during this period. Among them, 4 patients with a preoperative Qmax <15 ml/s and 2 patients with postoperative urinary retention were excluded. The analysis was therefore based on 625 patients. Bladder perforation occurred in 2 patients, which was treated with urethral catheterization. The urethral catheter was removed after confirmation of no urine leakage on a cystogram after 1 week. The mean age of the study population was 51.6 (range, 31-96) years and parity was 2.5 (range, 0-9). The mean duration of follow-up was 7.4±3.6 (range, 6-9) months. Of the 625 patients, 204 had grade I, 405 had grade II, and 16 had grade III SUI. Coexistent cystocele and rectocele were observed in 310 and 37 patients, respectively. The mean Valsalva leak point pressure (VLPP) was 62.7±29.1 cmh 2O. Postoperatively, 474 (76.1%) patients were cured and 133 (21.2%) were improved. There were no statistically significant differences in surgical outcomes according to symptom grade (Stamey grade), cystocele, VLPP, previous pelvic operation, concomitant vaginal operations, or

764 Korean Journal of Urology vol. 50, 762-766, August 2009 Table 1. Comparisons of demographic data between the postoperative voiding dysfunction group (Group 1) and the normal voiding group (Group 2) Total patients Group 1 Group 2 p-value No. of patients 625 163 462 Age (years) 51.6±9.4 51.2±9.3 53.1±9.9 0.124 a Body mass index 25.1±3.2 25.1±3.2 25.2±3.4 0.810 a Diabetes mellitus (+) 34 (5.4%) 8 (7.5%) 26 (5.0%) 0.829 b Parity (number of birth) 2.5±1.6 2.5±1.1 2.6±1.2 0.639 b Stamey sx grade (I/II/III) 204/405/16 38/64/5 166/341/11 0.843 b Cystocele (I/II/III/IV) 207/79/19/5 36/22/5/2 171/57/14/3 0.721 b Rectocele 37 9 28 0.562 b Surgical methods TVT TVTO TOT TVT-secure Preoperative Qmax (ml/sec) Voided volme (ml) Postvoid, residual (ml) Pdetmax (mmhg) 245 128 115 131 21.3±11.7 249.0±129.2 30.3±34.9 21.7±14.4 25.2±10.2 268.5±132.9 20.7±43.7 20.5±12.2 <0.001 a 0.172 a 0.922 a 0.416 a Delta Qmax (ml/sec) 11.79±6.65 4.9±6.55 <0.001 a,c TVT: tension-free vaginal tape, TVTO: tension-free vaginal tape obturator, TOT: tension-free obturator tape, Qmax: maximal uroflow rate, Delta Qmax: postoperative Qmax-preoperative Qmax, a : independent-sample t-test, b : Pearson's chi-square test, c : paired t-test 52 32 21 23 193 96 94 108 0.294 different kinds of tape devices. Postoperative voiding dysfunction was observed in 156 patients, in whom only 12 patients presented with obvious voiding symptoms. Of the 12 patients with voiding symptoms, 3 complained of weak stream, 2 of residual urinary sensations, and 7 of frequency. Of these 12, 5 patients has a Qmax<15 ml/s or PVR>100 ml. All 3 with weak stream had a Qmax <15 ml/s with PVR>100 ml. Two patients with residual urinary sensation had a Qmax<15 ml/s. Among the 18 patients with PVR>100 ml, 7 patients had PVR>200 ml, requiring intermittent catheterization. One of them presented with a large amount (308 ml) of PVR and was treated with postvoid catheterization without symptom improvement; therefore, the tape was released at 5 months after the MUS procedure. Meanwhile, 132 patients in whom postoperative Qmax decreased to <15 ml/s showed no voiding symptoms, and among these, only 9 patients presented with residual urine volume over 100 ml. In the comparative analysis of preoperative parameters between the normal voiding group (group 2) and the voiding dysfunction group (group 1) postoperatively, preoperative Qmax was significantly lower in group 1 than in group 2 (p= 0.294; 21.3±11.7 ml/s in group 1 and 25.2±10.2 ml/s in group 2, respectively) (Table 1). The other variables such as surgical methods, age, BMI, parity, DM, cystocele, and urodynamic variables did not differ significantly between groups. The mean change in Qmax (postoperative Qmax-preoperative Qmax) was significantly greater in group 1 than in group 2. To explore the risk factors for postoperative de novo voiding dysfunction, multiple logistic regression was performed and preoperative Qmax was found to be the only risk factor. As the preoperative Qmax increased by 1 ml/s, the risk of postoperative voiding dysfunction decreased by a factor of 0.95 (Table 2). The other variables such as age, BMI, and parity did not show statistical differences in the multiple regression analysis. DISCUSSION MUS is the single most common surgical modality for the treatment of SUI, with good results and few complications. In MUS, the sling provides dynamic kinking of the urethra when abdominal pressures increase, while maintaining stability at the resting phase, consequently preventing urinary incontinence. 16

Hoon Ah Jang, et al:incidence and Risk Factors of Postop. Voiding Dysfunction following MUS 765 Table 2. Analysis of risk factors for postoperative voiding dysfunction after midurethral sling OR 95% CI p-value a Age 1.012 50.90-52.37 0.518 Height 1.107 15.21-16.06 0.582 Weight 0.901 60.90-62.11 0.700 Body mass index 0.803 24.89-25.40 0.754 Parity 0.987 2.33-2.50 0.831 Diabetes mellitus 0.908 0.601 Symptom duration 0.998 49.57-59.26 0.321 Cystocele 1 2 3 4 Symptom grade 1 2 3 Preoperative Qmax (ml/sec) Postvoid, residual (ml) Pdetmax (mmhg) 0.776 1.454 0.862 1.103 0.091 0.546 0.95 1.00 0.985 23.73-25.0 17.48-24.11 21.45-22.72 0.814 1.459 0.834 0.993 0.688 0.650 <0.001 1.000 0.985 OR: odds ratio, CI: confidence interval, Qmax: maximal uroflow rate, a : logistic regression analysis Thus, theoretically, MUS doesn t cause voiding dysfunction including weak stream, urinary hesitancy, or straining voiding. Clinical risk may not be significant in the case of decreased Qmax after MUS if the patient does not have voiding symptoms and has an acceptable PVR. However, considering the possible long-term consequences on the bladder and upper urinary tract, even if patients do not present voiding symptoms, a decrease in Qmax should be carefully monitored. The incidence of voiding dysfunction after the MUS procedure has been reported to be from 4% to 55%. 2,3,10 Also, changes in the postoperative emptying phase, such as a decrease of Qmax, obstructive pattern on uroflowmetry, and increase of PVR have been reported. 7,17,18 It is commonly agreed that MUS compresses the midurethra, thus affecting voiding during the emptying phase. Our study showed the cure and improvement rate of SUI to be 76.1% and 21.4%, respectively, which is similar to the results of other studies. 19,20 In our study, postoperative evaluation was performed at least 6 months after the MUS procedure. Qmax was significantly decreased postoperatively, but the voided volume and PVR showed no significant changes. Boustead and Singh 6 reported a decrease in Qmax from 30-35 ml/s to 20-25 ml/s after the TVT procedure. Sander et al 18 also reported decreased Qmax, increased PVR, and obstructive pattern of uroflow after TVT. But less than half of those patients showed symptoms of voiding dysfunction postoperatively. In our study, a low Qmax preoperatively was shown as a risk factor of de novo postoperative voiding dysfunction, whereas the individual decreased range of Qmax after the MUS procedure was greater in the de novo voiding dysfunction group than in the normal voiding group. Saline et al 3 reported that 20% of patients presented with decreased Qmax of less than 15 ml/s and risk factors for decreased Qmax were age and preoperative low Qmax, which was comparable to our results. Taken together, the above results indicate that a low preoperative Qmax is a risk factor for postoperative presence of voiding dysfunction. Decrease of Qmax postoperatively may also occur in patients with low Pdetmax or bladder outlet obstruction. However, in our study, there was no difference in the preoperative Pdetmax between groups, suggesting that the postoperative decrease of Qmax was not affected by preoperative low Pdetmax or bladder outlet obstruction. On the other hand, Wang et al 17 defined voiding dysfunction as PVR above 100 ml and low preoperative Qmax and reported that postoperative urinary infection was one of the risk factors of postoperative voiding dysfunction. In our study, only a small portion of the patients with objective de novo voiding dysfunction (Qmax<15 ml/s or PVR >100 ml) were symptomatic. These findings indicated that the significant changes in objective clinical parameters such as Qmax or PVR did not overlap with the symptoms the patients felt, indicating the necessity to identify patients with potential postoperative voiding dysfunction by regular uroflowmetry and PVR measurement, especially in high-risk groups. According to other reports on the incidence of postoperative de novo voiding dysfunction according to MUS procedure, Daneshgari et al 21 found no differences according to the method of inserting the tape. Latthe et al 22 also reported the same conclusion, with findings similar to ours. The method used to insert the tape did not seem to affect the development of postoperative voiding dysfunction. To summarize, our findings indicate that with a lower preoperative Qmax, the incidence of postoperative voiding dysfunction became higher. In women with low preoperative Qmax, a longer-term, regular follow-up should be recommended to minimize the possible adverse consequences caused

766 Korean Journal of Urology vol. 50, 762-766, August 2009 by de novo voiding dysfunction. CONCLUSIONS In our study, a considerable rate of postoperative de novo voiding dysfunction, although mostly asymptomatic, did exist. Preoperative peak flow rate was regarded as the only risk factor for postoperative de novo voiding dysfunction. There were no differences in the incidence according to method of MUS. In patients with low preoperative Qmax, the MUS procedure should be performed carefully, considering the potential for postoperative de novo voiding dysfunction. REFERENCES 1. Ulmsten U, Henriksson L, Johnson P, Varhos G. An ambulatory surgical procedure under local anesthesia for treatment of female urinary incontinence. Int Urogynecol J Pelvic Floor Dysfunct 1996;7:81-5 2. Novara G, Galfano A, Boscolo-Berto R, Secco S, Cavalleri S, Ficarra V, et al. Complication rates of tension-free midurethral slings in the treatment of female stress urinary incontinence: a systematic review and meta-analysis of randomized controlled trials comparing tension-free midurethral tapes to other surgical procedures and different devices. Eur Urol 2008;53: 288-308 3. Salin A, Conquy S, Elie C, Touboul C, Parra J, Zerbib M, et al. Identification of risk factors for voiding dysfunction following TVT placement. Eur Urol 2007;51:782-7 4. Kim NS, Bae JH, Lee JG. Long-term follow-up of the tension-free vaginal tape (TVT) procedure for treating female stress urinary incontinence. Korean J Urol 2006;47:729-33 5. Koh JS, Kim HS, Kim HW, Lee YS, Kim SI, Lee KS, et al. Comparison of secondary procedures for recurrent stress urinary incontinence after a transobturator tape procedure: shortening of the tape versus tension-free vaginal tape redo. Korean J Urol 2007;48:1149-54 6. Boustead GB, Singh S. Outcome of TVT sling procedure in a single UK institution. BJU Int 2000;86(Suppl 3):77 7. Olujide LO, O'Sullivan SM. Female voiding dysfunction. Best Pract Res Clin Obstet Gynaecol 2005;19:807-28 8. Hong B, Park S, Kim HS, Choo MS. Factors predictive of urinary retention after a tension-free vaginal tape procedure for female stress urinary incontinence. J Urol 2003;170:852-6 9. Sokol AI, Jelovsek JE, Walters MD, Paraiso MF, Barber MD. Incidence and predictors of prolonged urinary retention after TVT with and without concurrent prolapse surgery. Am J Obstet Gynecol 2005;192:1537-43 10. Kuuva N, Nilsson CG. A nationwide analysis of complications associated with the tension-free vaginal tape (TVT) procedure. Acta Obstet Gynecol Scand 2002;81:72-7 11. 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 Gynaecol 1999;106: 345-50 12. Klutke C, Siegel S, Carlin B, Paszkiewicz E, Kirkemo A, Klutke J. Urinary retention after tension-free vaginal tape procedure: incidence and treatment. Urology 2001;58:697-701 13. Meschia M, Pifarotti P, Bernasconi F, Guercio E, Maffiolini M, Magatti F, et al. Tension-free vaginal tape: analysis of outcomes and complications in 404 stress incontinent women. Int Urogynecol J Pelvic Floor Dysfunct 2001;12(Suppl 2): S24-7 14. Lee JG, Choo MS, Lee KS, Yoo TK, Seo JT, Kim JC. Female voiding dysfunction treatment guideline. Female voiding dysfunction treatment guideline 2008. 2008;13 15. Stamey TA. Endoscopic suspension of the vesical neck for urinary incontinence in females. Report on 203 consecutive patients. Ann Surg 1980;192:465-71 16. Choi H, Lee JG. Preoperative factors affecting postoperative voiding difficulty after tension-free vaginal tape (TVT) operation. Korean J Urol 2004;45:982-7 17. Wang KH, Wang KH, Neimark M, Davila GW. Voiding dysfunction following TVT procedure. Int Urogynecol J Pelvic Floor Dysfunct 2002;13:353-7 18. Sander P, Moller LM, Rudnicki PM, Lose G. Does the tension-free vaginal tape procedure affect the voiding phase? Pressure-flow studies before and 1 year after surgery. BJU Int 2002;89:694-8 19. Richter HE, Norman AM, Burgio KL, Goode PS, Wright KC, Benton J, et al. Tension-free vaginal tape: a prospective subjective and objective outcome analysis. Int Urogynecol J Pelvic Floor Dysfunct 2005;16:109-13 20. Andonian S, Chen T, St-Denis B, Corcos J. Randomized clinical trial comparing suprapubic arch sling (SPARC) and tension-free vaginal tape (TVT): one-year results. Eur Urol 2005;47:537-41 21. Daneshgari F, Kong W, Swartz M. Complications of mid urethral slings: important outcomes for future clinical trials. J Urol 2008;180:1890-7 22. Latthe PM, Foon R, Toozs-Hobson P. Transobturator and retropubic tape procedures in stress urinary incontinence: a systematic review and meta-analysis of effectiveness and complications. BJOG 2007;114:522-31