Outcomes of Artificial Urinary Sphincter Implantation in Patients with Detrusor Underactivity and Postprostatectomy Incontinence Kyu Hun Han1, Joon Chul Kim1, Woong Jin Bae2, Jin Bong Choi1, Jun Sung Koh1, Kang Jun Cho1* Purpose: There is insufficient evidence for postoperative outcomes of artificial urinary sphincter (AUS) implan- tation for postprostatectomy incontinence (PPI) with detrusor underactivity (DU). Thus, we assessed the impact of preoperative DU on the outcomes of AUS implantation for PPI. Materials and Methods: Medical records of men who underwent AUS implantation for PPI were reviewed. Patients who had bladder outlet obstruction surgery before radical prostatectomy or AUS-related complications that required revision of AUS within three months were excluded. Patients were divided into two groups based on the preoperative urodynamic study including pressure flow study, a DU group, and a non-DU group. DU was defined as a bladder contractility index less than 100. The primary outcome was postoperative postvoid residual urine volume (PVR). The secondary outcomes included maximum flow rate (Qmax), postoperative satisfaction, and international prostate symptom score (IPSS). Results: A total of 78 patients with PPI were assessed. The DU group consisted of 55 patients (70.5%) and the non- DU group comprised 23 patients (29.5%). Qmax was lower in the DU group than in the non-DU group and PVR was higher in the DU group as per a urodynamic study before AUS implantation. There was no significant differ- ence in postoperative PVR between the two groups, although the Qmax after AUS implantation was significantly lower in the DU group. While the DU group showed significant improvements in Qmax, PVR, IPSS total score, IPSS storage subscore, and IPSS quality of life (QoL) score after AUS implantation, the non-DU group showed postoperative improvement in IPSS QoL score. Conclusion: There was no clinically significant impact of preoperative DU on the outcome of AUS implantation for PPI; thus, surgery can be safely performed in patients with PPI and DU. Keywords: artificial urinary sphincter; underactive bladder; urinary stress incontinence INTRODUCTION Radical prostatectomy may improve bladder func-tion by resolving bladder outlet obstruction (BOO), which is one of the main pathophysiologies of male lower urinary tract dysfunction. However, radical prostatectomy may worsen lower urinary tract symp- toms (LUTS) owing to changes in the neural circuit of the lower urinary tract, including the urethral sphincter. (1) Radical prostatectomy can cause urethral sphincter deficiency and detrusor function changes such as detru- sor underactivity (DU) or detrusor overactivity (DO).(2) Postprostatectomy incontinence (PPI) is known to have a significant impact on patients’ quality of life (QoL). It is most severe in the first two months post-surgery, but improves over time.(3) Unfortunately, some patients only recover partially, which influences their QoL and self-esteem. Surgical management of PPI can be offered to patients who still have incontinence after one year of conservative treatment. One retrospective analysis showed that approximately 3.3% of PPI cases received 1Department of Urology, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 2Department of Urology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. *Correspondence: Department of Urology, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 327 Sosa-ro, Bucheon-si, Gyeonggi-do 14647, Republic of Korea. Telephone: +82-32-340-7730; E-mail: gift99@catholic.ac.kr. Received August 2022 & Accepted March 2023 anti-incontinence surgery within two years after prosta- tectomy.(4) A variety of methods and devices are avail- able for patients undergoing anti-incontinence surgery, including bulking agents, male slings, and artificial uri- nary sphincters (AUS). AUS has been the gold standard for surgical intervention in PPI, as the literature shows high satisfaction and success rates.(5-7) The prevalence of DU after radical prostatectomy has been reported in 14%-51% of patients, and PPI with DU was observed in 44% of patients after radical prostatec- tomy.(8-10) One important concern that may arise after bladder outlet procedures for PPI in patients with DU is the possible aggravation of voiding problems, such as urinary retention. A previous study reported that a male sling for PPI did not affect residual urine volume and can be safely used in men who have DU but void normally.(11) However, a single report is not sufficient to represent the results of all bladder outlet procedures for PPI with DU, and male slings are sometimes con- sidered a contraindication for patients with DU because of possible urinary retention.(12) AUS implantation has RECONSTRUCTIVE SURGERY Urology Journal/Vol 20 No. 4/ July-August 2023/ pp.234-239. [DOI:10.22037/uj.v20i.7403] generally been performed for such patients in clinical practice, but there is a lack of sufficient evidence on postoperative outcomes. As urethral catheterization for urinary retention after AUS implantation is associated with device survival and urethral erosion, it is important to ensure that AUS can be safely used in patients with DU.(13) Here, we compared the outcomes of AUS for PPI be- tween patients with and without DU patients. This study aimed to determine whether AUS can be applied in patients with and without DU without postoperative complications related to voiding function. MATERIALS AND METHODS A retrospective review was conducted in patients with PPI who underwent AUS implantation from January 2010 to December 2019 and were followed up for longer than three months post-surgery. The patients’ preop- erative urodynamic study (UDS) results, including a pressure-flow study, were reviewed. Exclusion criteria included patients who had bladder outlet obstruction surgery before radical prostatectomy or AUS-related complications that required revision of the device with- in three months of implantation. AUS implantation was performed by one of the two experienced urologists (JCK and WJB). The AMS800TM (American Medical System, Inc., Minnetonka, MN, USA) urinary control system was implanted through a perineal or penoscro- tal incision. All patients received single bulbar urethral cuffs (3.5-4.5 cm), had a balloon reservoir placed in the right lower quadrant of the preperitoneal space through a separate lower abdominal incision and had a pump in the scrotum. The cuff size was determined by measur- ing the periurethral circumference with a cuff sizer en- closed in the AMS800 kit after careful dissection of the urethra. The implanted cuff was tested under urethros- copy before closing the wound to ensure that the urethra was open and closed with adequate pressure from the cuff. The device was activated six weeks after implanta- tion. This study was approved by the ethics committee and the institutional review board of our center. (HIRB- 20211221-016) Preoperative evaluation included age, body mass in- dex, International Prostate Symptom Score (IPSS), and UDS results. UDS was performed in accordance with the Good Urodynamic Practice standards recommend- ed by the International Continence Society (ICS).(14) Investigated postoperative results were maximum flow rate (Qmax), postvoid residual urine volume (PVR), IPSS, stress urinary incontinence (SUI) status, and pa- tient satisfaction. These factors were evaluated three months after AUS implantation. The enrolled patients were divided into two groups, DU and non-DU groups, based on preoperative urodynamics. DU was defined as a bladder contractility index (BCI) less than 100.(15) Surgical method of AUS implantation was the same for every patient, regardless of which group the patient was allocated. Preoperative factors and postoperative results were compared between the two groups. The primary outcome was postoperative PVR. Secondary outcomes included postoperative treatment satisfaction, SUI sta- tus, changes in Qmax, changes in IPSS, and compli- cations. Subjective patient outcomes were defined as follows: ‘cured’ was defined as one or less pad per day for use in social situations, ‘improved’ was defined as more than a 50% decrease in frequency and amount of urine leakage, and all other outcomes were regarded as ‘failed’. Treatment satisfaction was analyzed according to patient responses as ‘satisfied’, ‘neutral’, and ‘dis- satisfied’. Numerical variables are reported as means with stand- ard errors of the mean. Nominal variables are expressed as counts and percentages. The variables were statisti- Variables Total (N = 78) DU group (N = 55) Non-DU group (N = 23) P-value Age, year 70.2 ± 0.8 69.6 ± 0.9 71.7 ± 1.3 .212 BMI, kg/m2 24.4 ± 0.3 24.1 ± 0.3 24.7 ± 0.5 .298 History of radiation 24 (30.8) 19 (34.5) 5 (21.7) .297 Diabetes 15 (19.2) 12 (21.8) 3 (13.0) .532 Hypertension 44 (56.4) 32 (58.2) 12 (52.2) .803 Medication on anticholinergics 41 (52.6) 29 (52.7) 12 (52.2) .964 IPSS total 16.9 ± 1.8 17.5 ± 2.2 15.8 ± 2.9 .658 IPSS storage subscore 8.5 ± 0.8 8.8 ± 0.9 7.8 ± 1.3 .539 IPSS voiding subscore 8.5 ± 1.1 8.7 ± 1.4 8.0 ± 1.9 .782 IPSS QoL score 4.6 ± 0.2 4.7 ± 0.3 4.2 ± 0.4 .335 Urodynamic parameters Qmax, mL/s 12.2 ± 0.9 8.6 ± 0.5 20.8 ± 1.6 < .001* Voided volume, mL 242.1 ± 12.9 224.5 ± 16.3 283.7 ± 18.1 .036* PVR, mL 49.8 ± 10.6 66.9 ± 14.4 9.9 ± 4.2 < .001* Maximum cystometric capacity, mL 293.4 ± 11.7 295.4 ± 14.9 288.7 ± 18.1 .798 VLPP, cmH2O 83.4 ± 3.5 81.5 ± 4.4 87.9 ± 5.7 .412 Compliance 1.000 < 20 mL/cmH2O 8 (10.3) 6 (10.9) 2 (8.7) ≥ 20 mL/cmH2O 70 (89.7) 49 (89.1) 21 (91.3) PdetQmax, cmH 2 O 18.5 ± 2.1 17.7 ± 1.9 20.4 ± 5.4 .637 BCI 79.5 ± 4.1 60.7 ± 2.7 124.2 ± 5.1 < .001* MUCP, cmH2O 38.4 ± 2.9 39.0 ± 3.4 37.1 ± 5.9 .765 BOO index 7.8 ± 1.8 7.4 ± 1.5 8.6 ± 4.9 .277 Detrusor overactivity 8 (10.2) 7 (12.7) 1 (4.3) .097 Table 1. Baseline clinical characteristics and urodynamic parameters of enrolled patients Data are presented as mean ± standard error of mean or number (%) Abbreviations: DU, detrusor underactivity; BMI, body mass index; IPSS, International Prostate Symptom Score; QoL, quality of life; Qmax, maximal flow rate; PVR, post-void residual; MUCP, maximal urethral closure pressure; PdetQmax, detrusor pressure at maximal flow; BOO, bladder outlet obstruction; BCI, bladder contractility index; VLPP, Valsalva leak point pressure * Statistically significant. Outcomes of AUS in detrusor underactivity and postprostatectomy incontinence-Han et al. Vol 20 No 4 July-August 2023 235 Recunstructive Surgery 236 cally compared using the Student’s t-test, paired t-test, Mann-Whitney U test, or Wilcoxon's signed-rank test for continuous variables and the chi-square or Fisher's exact tests for categorical variables. Statistical analyses were performed using IBM SPSS Statistics for Win- dows (version 20.0; IBM Corp., Armonk, NY, USA). A P-value of < .05 was considered significant. The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately in- vestigated and resolved. This study was performed in accordance with the Declaration of Helsinki (as revised in 2013) and the Ethical Guidelines for Clinical Studies. The study protocol was reviewed and approved by the institutional review board of The Catholic University of Korea Bucheon St. Mary’s Hospital (approval No. HIRB-20211221-016), and individual consent for this retrospective analysis was waived. RESULTS Of the 93 patients who underwent AUS for PPI in our center, 78 were included in the analysis. The DU and non-DU groups consisted of 55 (70.5%) and 23 (29.5%) patients, respectively. The mean follow-up period was 41.2 months. Table 1 shows the baseline clinical char- acteristics and preoperative urodynamic results of the two groups. Qmax was lower in the DU group than in the non-DU group (P < .001), while PVR was higher in the DU group than in the non-DU group (P < .001) in the urodynamic study before AUS implantation. The preoperative BCI was significantly lower in the DU group than in the non-DU group (P < .001). There was no significant difference in postoperative PVR between the DU group and non-DU group (18.7 ± 3.8 versus 18.9 ± 3.4, P = .986). Although Qmax after AUS implantation was significantly lower in the DU group (18.2 ± 1.5 versus 27.6 ± 2.6, P = .002), the subjective cure rates were 58.2% in the DU group and 52.2% in the non-DU group (P = .887) and the satisfac- tion rates were 60% in the DU group and 56.5% in the non-DU group (P = .662) (Table 2). In total patients, the IPSS total score (16.9 ± 1.8 to 12.2 ± 1.3, P = .022) and QoL score (4.6 ± 0.2 to 2.6 ± 0.2, P < .001) were significantly lower postoperatively than the baseline scores. However, postoperative IPSS scores did not differ between the two groups (Figure 1). While the DU group showed significant improvements in Qmax, PVR, IPSS total score, IPSS storage subscore, and IPSS Total (N = 78) DU group (N = 55) Non-DU group (N = 23) P-value Postoperative SUI status .887 Cured 44 (56.4) 32 (58.2) 12 (52.2) Improved 31 (39.7) 21 (38.2) 10 (43.5) Failed 3 (3.8) 2 (3.6) 1 (4.3) Satisfaction .662 Satisfied 46 (58.9) 33 (60.0) 13 (56.5) Neutral 28 (35.9) 19 (34.5) 9 (39.1) Dissatisfied 4 (5.1) 3 (5.5) 1 (4.4) Table 2. Treatment outcomes between DU group and non-DU group Data are presented as number (%) Abbreviations: DU, detrusor underactivity; SUI, stress urinary incontinence. Figure 1. Comparison of postoperative IPSS between DU and non-DU group. IPSS, International Prostate Symptom Score; DU, detrusor underactivity; QoL, quality of life. Outcomes of AUS in detrusor underactivity and postprostatectomy incontinence-Han et al. QoL score after AUS implantation, the non-DU group showed postoperative improvement in IPSS QoL score (Figure 2). One patient in the DU group required clean intermit- tent catheterization for temporary poor post-obstructive voiding. None of the patients in the non-DU group re- quired catheterization. Urethral stricture or erosion oc- curred in five patients: four in the DU group and one in the non-DU group (P = 1.000). Mechanical dysfunction occurred in a total of two patients, one in each group (P = .505). DISCUSSION Our study showed that voiding function after AUS im- plantation did not differ significantly regardless of the presence of DU before surgery. Postoperative Qmax was significantly lower in patients with DU than in those without non-DU; however, this did not lead to significant differences in postoperative PVR and satis- faction rates between the two groups. Voiding or storage function outcomes of AUS implan- tation for urinary incontinence with concomitant lower urinary tract dysfunction after prostatectomy have been reported since AUS has been used for the management of PPI. Mild bladder dysfunctions, such as small blad- der capacity, low compliance, and non-neurogenic blad- der overactivity, can sometimes be improved after AUS implantation, and they are not considered contrain- dications to AUS implantation for PPI.(16) There have been reported to depend on whether a patient voided by straining with minimal detrusor contraction, which can reflect decreased detrusor contractility during the void- ing phase after prostatectomy. Those reports showed that about 30%-50% of PPI patients voided by strain- ing, and this voiding pattern did not negatively affect the results of AUS implantation. There were no differ- ences in PVR and pad usage compared with those in patients with normal detrusor voiding patterns.(17,18) At present, there have been only a few studies on the influence of the cuff on urethral closure pressure in the deactivation or open state of the device. Bentellis et al. reported no significant difference between the preoper- ative maximum urethral closure pressure (MUCP) and postoperative MUCP in the open-state cuff.(19) We can infer that AUS implantation itself does not negatively influence voiding function, which is well supported by our results showing improved and no difference in postoperative PVR in the DU and non-DU groups, respectively. Queissert et al. suggested that small cuff size (3.5 cm) is a risk factor for urethral erosion.(20) This would make surgeons consider complications related to the cuff itself if patients have lower urinary tract dys- function before the insertion of an AUS. Further studies are needed to elucidate the influence of the cuff on the urethra and associated voiding function. One of the main mechanisms of DU after radical pros- tatectomy is detrusor denervation due to pelvic nerve injury during dissection of structures around the semi- nal vesicles.(21,22) Severe neurological changes or accu- mulation of neurological damage during radical pros- tatectomy can cause urinary retention; however, in our study, the average PVR in the DU group before AUS implantation was approximately 67 mL. This was not to the extent that urethral catheterization was required, although the average PVR in the DU group was higher than that of the non-DU group. Previous studies also showed that PVR before AUS implantation was less Figure 2. Changes in urodynamic parameters and IPSS after AUS implantation in DU and non-DU group. Qmax, maximum flow rate; PVR, postvoid residual; IPSS, International Prostate Symptom Score; QoL, quality of life ; DU, detrusor underactivity. * Statistically significant. Outcomes of AUS in detrusor underactivity and postprostatectomy incontinence-Han et al. Vol 20 No 4 July-August 2023 237 than 150 mL, even when voiding functions were im- paired in patients with PPI.(11,17) In the case of PPI, even if bladder function is significantly degraded, a consid- erable amount of urine can leak out through a weakened urethral sphincter before voiding. Voiding efficiency appears to be preserved by Valsalva voiding or abdom- inal straining. Therefore, PVR measured before AUS implantation may not be used to evaluate the severity of DU. In all patients, the subjective cure and satisfaction rates were 56% and 60%, respectively, with significant im- provement in the postoperative IPSS total score and QoL score in this study. The presence of DU did not affect postoperative outcomes. Lai et al. also demon- strated that preoperative voiding dysfunction did not negatively affect incontinence outcomes after AUS implantation.(23) A possible reason why DU did not af- fect the subjective cure rate is that the cuff was selected and applied according to consistent criteria during AUS surgery, regardless of the presence of DU. Additional- ly, there was no negative effect on storage symptoms such as increased DO after surgery. We believe that DU did not affect satisfaction after surgery because there was no significant difference in PVR between the two groups. The Qmax in each group improved after AUS implantation, although there was a difference in Qmax between the groups. Sphincteric incompetence has been suggested to be an important cause of PPI, and constant incontinence may lead to bladder dysfunction.(16,21,24) AUS not only pre- vents urine leakage but also stabilizes the urethra and bladder. Functional recovery of the bladder may have led to improvements in Qmax and PVR in patients with DU. This study has several limitations. First, the retrospec- tive and nonrandomized nature of our study should be noted. Second, there is currently no consensus on a standardized urodynamic methodology to diagnose DU with SUI. The main concept underlying DU is voiding dysfunction of the bladder due to low detrusor pressure. Urologists have used surrogate measurements from UDS to quantitatively evaluate detrusor functions, such as Qmax, detrusor pressure at the time of Qmax (PdetQmax), and BCI.(25) Jura and Comiter suggested using isometric detrusor contraction pressure (Piso) as a more appropriate measurement of detrusor con- tractility in patients with PPI due to intrinsic sphincter deficiency, since conventional PdetQmax can be un- derestimated in such patients.(26) However, as there is insufficient data on Piso, it seems too understudied to be used in practice. BCI has been devised to assess the bladder function of males in ‘standard’ situations, i.e., males with prostate cancer. Unfortunately, we do not have urodynamic data of patients before prostatectomy, therefore we do not know whether the patients had DU or not in the ‘standard’ situation. However, vesicoure- thral anastomosis after prostatectomy involves surgical techniques to reduce incontinence. Comparing BCI among postprostatectomy patients may have a role in assessing bladder function and predicting the outcomes of AUS implantation. Moreover, because we did not perform UDS after AUS implantation, we could not accurately evaluate the change in DU after AUS. In reality, it is not easy to recommend invasive UDS to patients unless there is a serious change in the LUTS after AUS implantation. In addition, objective evaluations, such as postopera- tive voiding diaries or pad tests for incontinence, were also insufficient. However, the purpose of this study was to evaluate whether DU negatively affects voiding symptoms after AUS implantation by investigating the representative parameters: Qmax, PVR, and patients’ voiding symptom questionnaire. CONCLUSIONS DU is relatively common in post-radical prostatectomy patients, and preoperative urodynamic data show dif- ferences in some parameters, such as Qmax and PVR, between DU and non-DU patients. However, the post- operative results suggest that AUS implantation could be safely recommended for PPI patients with DU with- out concerns about urinary retention or voiding dys- function. CONFLICT OF INTERESTS The authors have no conflicts of interest to declare. DATA AVAILABILITY STATEMENT The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. REFERENCES 1. Mitsui T, Tanaka H, Harabayashi T, et al. Changes in urodynamics and lower urinary tract symptoms after radical prostatectomy: implications of preoperative detrusor contractility. Low Urin Tract Symptoms. 2012;4:82-6. 2. Lee H, Kim KB, Lee S, et al. Urodynamic assessment of bladder and urethral function among men with lower urinary tract symptoms after radical prostatectomy: A comparison between men with and without urinary incontinence. Korean J Urol. 2015;56:803-10. 3. Sanda MG, Dunn RL, Michalski J, et al. Quality of life and satisfaction with outcome among prostate-cancer survivors. N Engl J Med. 2008;358:1250-61. 4. Kim JH, Jeong IG, Khandwala YS, Hernandez-Boussard T, Brooks JD, Chung BI. Prevalence of postprostatectomy incontinence requiring anti-incontinence surgery after radical prostatectomy for prostate cancer: a retrospective population-based analysis. Int Neurourol J. 2021;25:263-70. 5. Linder BJ, Rivera ME, Ziegelmann MJ, Elliott DS. Long-term outcomes following artificial urinary sphincter placement: an analysis of 1082 cases at Mayo Clinic. Urology. 2015;86:602-7. 6. Leon P, Chartier-Kastler E, Roupret M, Ambrogi V, Mozer P, Phe V. Long-term functional outcomes after artificial urinary sphincter implantation in men with stress urinary incontinence. BJU Int. 2015;115:951- 7. 7. O'Connor RC, Lyon MB, Guralnick ML, Bales GT. Long-term follow-up of single versus double cuff artificial urinary sphincter Outcomes of AUS in detrusor underactivity and postprostatectomy incontinence-Han et al. Recunstructive Surgery 238 insertion for the treatment of severe postprostatectomy stress urinary incontinence. Urology. 2008;71:90-3. 8. Walker NF, Canagasingham A, Van Diepen D, et al. Lower urinary tract functional assessment of men undergoing radical prostatectomy: correlation of preoperative clinical and urodynamic parameters. Int Neurourol J. 2021;25:157-63. 9. Chung DE, Dillon B, Kurta J, Maschino A, Cronin A, Sandhu JS. Detrusor underactivity is prevalent after radical prostatectomy: A urodynamic study including risk factors. Can Urol Assoc J. 2013;7:E33-7. 10. Giannantoni A, Mearini E, Zucchi A, et al. Bladder and urethral sphincter function after radical retropubic prostatectomy: a prospective long-term study. Eur Urol. 2008;54:657-64. 11. Han JS, Brucker BM, Demirtas A, Fong E, Nitti VW. Treatment of post-prostatectomy incontinence with male slings in patients with impaired detrusor contractility on urodynamics and/or who perform Valsalva voiding. J Urol. 2011;186:1370-5. 12. Hennessey DB, Hoag N, Gani J. Impact of bladder dysfunction in the management of post radical prostatectomy stress urinary incontinence-a review. Transl Androl Urol. 2017;6:S103-s11. 13. Linder BJ, Piotrowski JT, Ziegelmann MJ, Rivera ME, Rangel LJ, Elliott DS. Perioperative complications following artificial urinary sphincter placement. J Urol. 2015;194:716-20. 14. Drake MJ, Doumouchtsis SK, Hashim H, Gammie A. Fundamentals of urodynamic practice, based on International Continence Society good urodynamic practices recommendations. Neurourol Urodyn. 2018;37:S50-s60. 15. Abrams P. Bladder outlet obstruction index, bladder contractility index and bladder voiding efficiency: three simple indices to define bladder voiding function. BJU Int. 1999;84:14-5. 16. Afraa TA, Campeau L, Mahfouz W, Corcos J. Urodynamic parameters evolution after artificial urinary sphincter implantation for post-radical prostatectomy incontinence with concomitant bladder dysfunction. Can J Urol. 2011;18:5695-8. 17. Gomha MA, Boone TB. Voiding patterns in patients with post-prostatectomy incontinence: urodynamic and demographic analysis. J Urol. 2003;169:1766-9. 18. Lai HH, Hsu EI, Teh BS, Butler EB, Boone TB. 13 years of experience with artificial urinary sphincter implantation at Baylor College of Medicine. J Urol. 2007;177:1021- 5. 19. Bentellis I, El-Akri M, Hascoet J, et al. Determinants and prognostic value of post- operative maximum urethral closure pressure after artificial urinary sphincter in men. World J Urol. 2020;38:1303-9. 20. Queissert F, Huesch T, Kretschmer A, et al. Artificial urinary sphincter cuff size predicts outcome in male patients treated for stress incontinence: results of a large central european multicenter cohort study. Int Neurourol J. 2019;23:219-25. 21. Chao R, Mayo ME. Incontinence after radical prostatectomy: detrusor or sphincter causes. J Urol. 1995;154:16-8. 22. Hollabaugh RS, Jr., Dmochowski RR, Kneib TG, Steiner MS. Preservation of putative continence nerves during radical retropubic prostatectomy leads to more rapid return of urinary continence. Urology. 1998;51:960-7. 23. Lai HH, Hsu EI, Boone TB. Urodynamic testing in evaluation of postradical prostatectomy incontinence before artificial urinary sphincter implantation. Urology. 2009;73:1264-9. 24. Winters JC, Appell RA, Rackley RR. Urodynamic findings in postprostatectomy incontinence. Neurourol Urodyn. 1998;17:493-8. 25. Osman NI, Chapple CR, Abrams P, et al. Detrusor underactivity and the underactive bladder: a new clinical entity? A review of current terminology, definitions, epidemiology, aetiology, and diagnosis. Eur Urol. 2014;65:389-98. 26. Jura YH, Comiter CV. Urodynamics for postprostatectomy incontinence: when are they helpful and how do we use them? Urol Clin North Am. 2014;41:419-27, viii. Outcomes of AUS in detrusor underactivity and postprostatectomy incontinence-Han et al. Vol 20 No 4 July-August 2023 239