1158072 research-article20232023 TAU0010.1177/17562872231158072Therapeutic Advances in UrologyV Gauhar, CA Chai Therapeutic Advances in Urology Original Research RIRS with disposable or reusable scopes: Ther Adv Urol 2023, Vol. 15: 1–10 does it make a difference? Results from the DOI: 10.1177/ https://doi.org/10.1177/17562872231158072 https://doi.org/10.1177/17562872231158072 17562872231158072 multicenter FLEXOR study © The Author(s), 2023. Article reuse guidelines: sagepub.com/journals- permissions Vineet Gauhar, Chu Ann Chai, Ben H Chew, Abhishek Singh, Daniele Castellani, Thomas Tailly, Esteban Emiliani, William Ong Lay Keat, Deepak Ragoori, Mohamed Amine Lakmichi, Jeremy Yuen-Chun Teoh, Olivier Traxer and Bhaskar Kumar Somani Correspondence to: Bhaskar Kumar Somani Department of Urology, Abstract University Hospital Southampton NHS Introduction: With several single-use ureteroscopes now available, our aim was to analyze Foundation Trust, and compare data obtained globally from high-volume centers using both disposable and Southampton SO16 6YD, UK reusable flexible ureteroscopes and see if indeed in real-world practice either scope has a bhaskarsomani@yahoo. com distinct advantage. Vineet Gauhar Methods: Retrospective analysis was performed on the FLEXOR registry, which was created Department of Urology, Ng Teng Fong General as a TOWER group (Team of Worldwide Endourological Researchers, research wing of the Hospital, Singapore Endourological Society) endeavor. Patients who underwent retrograde intrarenal surgery Chu Ann Chai (RIRS) for renal stones from January 2018 to August 2021 were enrolled from 20 centers Urology Unit, Department of Surgery, University of globally. A total of 6663 patients whose data were available for analysis were divided into Malaya, Kuala Lumpur, Malaysia Group 1 (Reusable scopes, 4808 patients) versus Group 2 (Disposable scopes, 1855 patients). Ben H Chew Results: The age and gender distribution were similar in both groups. The mean stone Department of Urology, University of British size was 11.8 mm and 9.6 mm in Groups 2 and 1, respectively (p < 0.001). Group 2 had more Columbia, Vancouver, BC, patients with >2 cm stones, lower pole stones and of higher Hounsfield unit. Thulium fiber Canada Abhishek Singh laser (TFL) was used more in Group 2 (p < 0.001). Patients in Group 2 had a slightly higher Muljibhai Patel Urological stone-free rate (SFR) (78.22%) and a lower number of residual fragments (RFs) compared Hospital, Nadiad, India with Group 1 (p < 0.001). The need for further treatments for RF and overall complications was Daniele Castellani Urology Unit, Azienda comparable between groups. On multivariate analysis, overall complications were more likely Ospedaliero-Universitaria delle Marche, Università to occur in elderly patients, larger stone size, lower pole stones, and were also more when Politecnica delle Marche, using disposable scopes with longer operative time. RFs were significantly higher (p < 0.001) Ancona, Italy. Thomas Tailly for lower pole, larger, harder, multiple stones and in elderly. Department of Urology, Conclusion: Our real-world practice observations suggest that urologists choose disposable University Hospital of Ghent, Ghent, Belgium scopes for bigger, lower pole, and harder stones, and it does indeed help in improving the Esteban Emiliani single-stage SFR if used correctly, with the appropriate lasers and lasing techniques in expert Urology Department, Fundación Puigvert, hands. Universidad Autónoma de Barcelona, Barcelona, Spain Keywords: disposable, kidney calculi, laser, RIRS, ureteroscopy William Ong Lay Keat Department of Urology, Penang General Hospital, Received: 12 December 2022; revised manuscript accepted: 31 January 2023. Penang, Malaysia Deepak Ragoori Asian Institute of Nephrourology, Introduction is considered suitable for RIRS and instrument Hyderabad, India Mohamed Amine Lakmichi Retrograde intrarenal surgery (RIRS) has estab- and lithotripsy advancements help push the upper Department of Urology, lished itself in mainstream guidelines1–3 as a safe limit of stone volume that can be managed with University Hospital Mohammed the VIth of alternative to percutaneous nephrolithotomy RIRS and as technology changes its periodically Marrakesh, Marrakesh, (PCNL) in managing renal stones.4 A 2 cm cut-off reviewed by the guidelines committee as well.5 Morocco journals.sagepub.com/home/tau 1 Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). Therapeutic Advances in Urology Volume 15 Jeremy Yuen-Chun Teoh Typically, urologists use reusable or disposable TOWER group (Team of Worldwide Endouro­ S.H. Ho Urology Centre, Department of Surgery, scopes for RIRS. The likelihood of scope dam- logical Researchers, research wing of the Faculty of Medicine, The age increases with higher stone volume and Endourological Society) endeavor. A total of Chinese University of Hong Kong, Shatin, Hong Kong stone numbers, which happens due to a reduc- 6669 patients who underwent RIRS for renal Olivier Traxer tion in tip deflection6 or working channel dam- stones from January 2018 to August 2021 were Department of Urology, AP-HP, Tenon Hospital, age.7 Needless to say, the high repair and enrolled from 20 centers globally, and only expert Sorbonne University, procurement costs strains resources and is dis- consultants who had performed more than 500 Paris, France ruptive to practice. Hence, disposable scopes RIRS cases using both disposable and reusable may be the ideal replacement or compliment scopes were invited to contribute cases. reusable scopes. Using a disposable scope each time provides advantages of getting a brand new A total of 6663 patients whose data were available sterile scope with perfect digital vision and for analysis were divided into Group 1 (Reusable excellent bi-directional deflection and ergonom- scopes) versus Group 2 (Disposable scopes). ically much lighter than fiberoptic or digital Decision to use a reusable or disposable scope scopes and absence of sterilization procedures and the brand of the scope was totally at the dis- with no hospital infections.8 Furthermore, cretion of the surgeon based on availability and newer disposable scopes have smaller calibers preference. and sturdier shafts and tips with much better active and passive deflection that allows access Only adult patients (⩾18 years old), with normal to all parts of the renal collecting system safely calyceal anatomy, were enrolled. Patients with and with no risk of scope damage due to maneu- ureteric stones, anomalous kidneys, bilateral verability.9 Finally, disposable scopes aid in pro- renal stones, and planned endoscopic combined viding training to residents without the worry of intrarenal surgery (ECIRS) were excluded from expensive repair in case of an accidental scope this study. Clinically significant residual frag- damage.10 Many small single-center studies ments (CSRFs) defined as single fragments have reported that disposable scopes fare better >2 mm or multiple fragments of any size requir- than reusable scope with regard to stone-free ing further treatments were assessed as per local rate (SFR) and infectious complications.11 practice with kidney, ureter, and bladder (KUB) Moreover, the quality and effectiveness of steri- X-rays and ultrasound or computed tomography lization of the reusable RIRS scopes is con- scan. stantly being questioned and several studies have addressed this.12 As this was a retrospective data entry and as prac- tices vary globally based on available resources, Since the successful launch of Lithovue disposa- no strict criteria on how to choose which scopes ble scope in 2016, several scopes have flooded the or which brands were applicable. market with each claiming better features and aimed at overcoming the shortcomings of reusa- bles.11 Our aim is to analyze data obtained glob- Statistical analyses ally from high-volume centers using both Baseline characteristics of the patients, presenting disposable and reusable scopes and see if indeed complaint, stone size, multiplicity, location, and in real-world practice either scope has a distinct perioperative characteristics, were analyzed. advantage minimizing the residual fragments Categorical variables are reported as absolute (RFs) post lithotripsy, and complications specifi- numbers and percentages, while continuous vari- cally fever and sepsis rates post-operatively, when ables are reported as mean and standard devia- used with different lasers and adjunct when tack- tion (SD). Kolmogorov–Smirnov test was used to ling calculi in specific locations, size, and check data distribution for normality and data on numbers. demographics, Hounsfield unit (HU), greatest transverse diameter, single versus multiple, loca- tion, type of lasers, intraoperative, postoperative Methods complications, and surgical time assessed. These characteristics between the two groups were ana- Study population and design lyzed using Pearson’s chi-square test and t-test. Retrospective analysis was performed on the Outcomes of surgery including length of hospital FLEXOR registry, which was created as a stays, presence of CSRF, and complications from 2 journals.sagepub.com/home/tau V Gauhar, CA Chai et al. surgery were analyzed using Pearson’s chi-square scopes, 79% were fibreoptic and 29% were digi- test and t-test as well. tal scopes. A multivariate logistic regression (MV) analysis Mean hospital stay was longer in Group 1 (3.96 was performed to predict the likelihood of over- versus 2.52 days) (Table 3). Patients in Group 2 all complications and RF. The covariates being had a slightly higher SFR (78.22%) and a lower analyzed were age, sex, recurrence stone, stone number of RFs compared with Group 1 (1210 size, multiple stones, lower pole (LP) stone, and versus 404, p < 0.001). pre-stenting. All statistical analyses were done using the IBM SPSS statistics, version 26 (IBM There can be considerable interobserver hetero- Corp, Armonk, NY). We considered two-tailed geneity in reporting RF using multiple modalities p-value less than 0.05 to be statistically and as a computed tomography (CT) scan is significant. more sensitive to reporting RF. When this was strictly applied overall, the number of RF reported were only 12.31% from 24.22%, an almost 50% Results reduction. Furthermore, RF in the reusable/ Patients’ demographics are shown in Table 1. Group 1 was reported significantly lower (11.21% Patients (n = 6663) were divided into two groups. versus 15.15%, p < 0.001) (Table 3). This reiter- A total of 4808 patients were in Group 1 while ates that imaging modality has a very big influ- 1855 patients underwent RIRS in Group 2. The ence on RF assessment post endoscopic age and gender distribution were similar in both intervention. The need for further treatments for groups with majority of patients aged 41–65 years RF and overall complications was comparable old. Disposable scopes were more commonly between both groups. used among Asian patients (74.61% versus 25.39%). On multivariate analysis (Table 4), overall com- plications were more likely to occur in elderly Statistically significantly (p < 0.001) higher num- patients, larger stone size, lower pole stones, and ber of symptomatic patients for pain (3064 versus were also more when using disposable scopes 1111), fever (524 versus 127), elevated creatinine with longer operative time. RFs were significantly (476 versus 136), positive pre-op culture (2156 higher (p < 0.001) for LP, larger, harder, multiple versus 230) and with multiple stones (2029 versus stones and in elderly. Disposable scopes were not 699) were seen in Group 1. associated with higher RF. Looking at the stone characteristics (Table 1), the mean stone size of patients in Group 2 (11.84 mm) Discussion was bigger than that in Group 1 (9.62 mm) Significant differences in physical and optical (p < 0.001). A subgroup analysis also showed properties of single-use or reusable flexible ure- Group 2 had more patients with stone larger than terorenoscopes exist, which have a variable 2 cm (201, p < 0.001), lower pole stones (47.06% influence on surgical efficacy during RIRS.13 versus 43.03%) and of higher Hounsfield Unit RIRS is an accepted safe intervention,14 and (1005.48 versus 967.58). advancement in size, optics, and lithotripsy adjuncts have put RIRS on center stage in mini- With regard to perioperative findings (Table 2), mally invasive intervention for renal stones up mean operating time was longer in Group 2 to 2 cm as a less invasive alternative to PCNL.4 (78.37 min versus 57.67 min, p < 0.001). Almost To date, the FLEXOR study by the TOWER half of the patients in both groups had preopera- group is the largest real-world registry reporting tive stenting, and majority of patients in Group on the outcome of RIRS exclusively for renal 2 utilized ureteral access sheath (UAS) during stones only using disposable and reusable surgery (99.62%). Significantly higher number scopes with different lasers from 20 centers of patients in Group 1 had laser lithotripsy with worldwide. Holmium lasers, especially using MOSES (8.74% versus 5.12%, p < 0.001). Thulium fiber Bozzini et al. reported a very high overall SFR of laser (TFL) was used more in Group 2 (53.69% 90% versus 86.6% in their prospective analysis of versus 26.85%, p < 0.001). In the reusable 180 patients undergoing RIRS with disposable journals.sagepub.com/home/tau 3 Therapeutic Advances in Urology Volume 15 Table 1. Patient demographics and stone characteristics. Overall Reusable Disposable p-value Group 1 Group 2 Patients characteristics No. of patients (%) 6663 (100) 4808 (72.1) 1855 (27.8) Missing data 6 Age (mean ± SD) 49.35 (15.59) 49.52 (16.06) 48.93 (14.29) <0.001   <40 (%) 2107 (31.62) 1525 (31.72) 582 (31.37) <0.001   41–65 (%) 3492 (52.41) 2465 (51.27) 1027 (55.36) <0.001   66–75 (%) 731 (10.97) 540 (11.23) 191 (10.30) <0.001   >76 (%) 331 (4.97) 278 (5.78) 53 (2.86) <0.001 Sex Male (%) 4403 (6608) 3168 (65.89) 1235 (66.58) 0.308 Female (%) 2260 (33.92) 1640 (34.11) 620 (33.42) 0.308 Asian (%) 4222 (63.36) 2838 (59.03) 1384 (74.61) <0.001 Non-Asian (%) 2441 (36.64) 1970 (40.97) 471 (25.39) <0.001 Presentation First time stone former (%) 5035 (75.57) 3631 (75.52) 1404 (75.69) 0.899 Hematuria (%) 325 (4.88) 241 (5.01) 84 (4.53) 0.038 Pain (%) 4175 (62.66) 3064 (63.73) 1111 (59.89) 0.001 Elevated creatinine (%) 612 (9.19) 476 (9.90) 136 (7.33) <0.001 Fever (%) 651 (9.77) 524 (10.90) 127 (6.85) <0.001 Positive urine C&S (%) 2386 (35.81) 2156 (44.84) 230 (12.40) <0.001 Stone characteristics Size (mean ± SD) 10.21 (7.25) 9.62 (6.61) 11.84 (8.59) <0.001 Stone <2 cm (%) 6271 (94.12) 4617 (96.02) 1654 (89.16) <0.001 Stone >2 cm (%) 392 (5.88) 191 (3.97) 201 (10.84) <0.001 Presence of multiple stones (%) 2728 (40.94) 2029 (42.20) 699 (37.68) <0.001 Lower pole stone (%) 2942 (44.15) 2069 (43.03) 873 (47.06) <0.001 Hounsfield unit (mean ± SD) 978.87 (333.13) 967.58 (332.14) 1005.48 (334.07) 0.001 SD, standard deviation. 4 journals.sagepub.com/home/tau V Gauhar, CA Chai et al. Table 2. Perioperative findings of the groups. Perioperative findings Overall Group 1 Group 2 p-value Reusable Disposable Imaging used (%) 4808 (72.1) 1855 (27.9) Fiberoptic (%) 3426 (71%) Digital (%) 382 (29%) 1855 (100%) Operating time (min) (mean ± SD) 62.46(44.57) 57.67 (43.84) 78.37 (43.29) <0.001 Preop stenting 3110 (46.68) 2216 (46.09) 894 (48.19) <0.001 UAS used (%) 6209 (93.19) 4361 (90.70) 1848 (99.62) <0.001 No UAS used (%) 454 (6.81) 447 (9.30) 7 (0.38) <0.001 Holmium laser (%) 4874 (73.15) 4023 (83.67) 851 (45.88) <0.001 Holmium laser < 30 W 2173 (32.61) 1445 (30.05) 728 (39.25) <0.001 Holmium laser > 30 W 2701 (40.54) 2268 (47.17) 433 (23.34) <0.001 Moses laser (%) 515 (7.73) 420 (8.74) 95 (5.12) <0.001 Thulium laser (%) 1789 (26.85) 793 (16.49) 996 (53.69) <0.001 SD, standard deviation; UAS, ureteral access sheath. Table 3. Perioperative outcomes of the groups. Overall Group 1 Group 2 p-value Reusable Disposable Hospital stays (mean ± SD) 3.62 (3.47) 3.96 (3.54) 2.52 (2.99) <0.001 Stone-free rate (%) 75.78 74.83 78.22 <0.001 Stone-free rate (%) based on CT only 87.69 88.79 84.85 <0.001 (n = 820) Residual fragments (%) 1614 (24.22) 1210 (25.17) 404 (21.78) <0.001 Residual fragments (%) based on CT 820 (12.31) 539 (11.21) 281 (15.15) <0.001 Re-intervention for RF (%) 742 (11.14) 485 (10.09) 257 (13.85) ESWL (%) 257 (3.86) 148 (3.08) 109 (5.88) 0.784 RIRS (%) 400 (6.00) 286 (5.95) 114 (6.15) 0.926 PCNL (%) 64 (0.96) 39 (0.81) 25 (1.35) 0.133 ECIRS (%) 21 (0.32) 12 (0.25) 9 (0.49) 0.290 Observation (%) 872 (13.09) 725 (15.08) 147 (7.92) <0.001 Overall complications (%) 609 (9.14) 407 (8.47) 202 (10.89) <0.001 (Continued) journals.sagepub.com/home/tau 5 Therapeutic Advances in Urology Volume 15 Table 3. (Continued) Overall Group 1 Group 2 p-value Reusable Disposable Grade I  Fever – within first 24 h needing 407 (6.11) 270 (5.62) 137 (7.39) <0.001 antibiotics (%) Grade II Sepsis (sepsis not needing ICU) (%) 84 (1.26) 51 (1.06) 33 (1.78) <0.001 Grade IV Ureteric injury (%) 118 (1.77) 86 (1.79) 32 (1.73) 0.002 Ureteric injury (needing reimplantation) 0 0 0 CT, computed tomography; ECIRS, endoscopic combined intrarenal surgery; ESWL, extracorporeal shock wave lithotripsy; ICU, intensive care unit; PCNL, percutaneous nephrolithotomy; RF, residual fragment; RIRS, retrograde intrarenal surgery; SD, standard deviation. Table 4. Multivariate logistic regression analysis of incidence of overall and reusable scopes and recommended using dis- complications and residual stone fragments (SF). posable scopes as they had significantly lesser complications and shorter hospital stay. In our OR (95% CI) p value registry, all centers used both reusable and dis- Overall complications posable scopes. We reported a better operative outcome in Group 2 patients, with higher SFR Age (years) 0.982 (0.974–0.991) <0.001 and lower incidence of RF (21.78% versus Sex 0.838 (0.643–1.093) 0.193 25.17%) despite the fact that Group 2 had bigger, harder (higher HU), and higher number of stones Stone size (mm) 1.039 (1.019–1.060) <0.001 in lower pole and larger number of stones >2 cm as well.11 Possibly, we can infer that in such situ- Multiple stones 0.412 (0.307–0.553) <0.001 ations and locations, surgeons want to maximize Lower pole stone 1.908 (1.471–2.475) having good vision/deflection and flow character- <0.001 istics which is exactly what a new disposable Disposable scope 2.136 (1.596–2.857) <0.001 scope offer upon each use8,9 and hence could account for the good outcomes and higher utiliza- Hounsfield unit 0.999 (0.998–0.999) 0.002 tion of disposable scopes. Operation time 1.007 (1.003–1.011) 0.001 This was cited by other studies and in particular it Residual stone fragments has been observed that as lower pole stones are the most significant risk factor for flexible ureter- Age (years) 1.015 (1.009–1.020) <0.001 oscope damage, single-use ureteroscopes could Sex 0.991 (0.832–1.181) 0.920 be preferentially used in anatomically difficult cases where a greater degree of deflection is Stone size (mm) 1.028 (1.017–1.040) <0.001 needed and the probability of the instrument Multiple stones 1.171 (1.025–1.339) 0.021 damage is higher.4,15 Lower pole stone 1.853 (1.557–2.204) <0.001 An unquestionable advantage of adding disposa- ble scopes to one armamentarium is that it can Disposable scope 0.905 (0.741–1.104) 0.323 help preserve a reusable scope’s longevity.6 Hounsfield unit 1.000 (0.999–1.000) 0.006 Kramolowsky et al.16 reported that on average a fiberoptic reusable scope needs repair/mainte- Operation time 1.008 (1.006–1.010) <0.001 nance after 21 uses, while upkeep of digital scopes CI, confidence interval; OR, odds ratio. ranges from 10 to 21 uses. Besides that, Ozimek et al.17 reported that infundibulo-pelvic angle of 6 journals.sagepub.com/home/tau V Gauhar, CA Chai et al. 60° or less translate to exaggerated deflection complication and occurred in both groups, and which is a risk factor for scope damage. A com- sepsis rates were only marginally more in Group mon recommendation to preserve scope longevity 2. Group 1 patients might have had lesser infec- is to displace the lower pole stone to a better loca- tive complications as a larger number received tion for easier lithotripsy.6 However, often the preoperative antibiotics following a positive pre- stone size and Pelvicalyceal system (PCS) anat- operative urine culture (Table 1). This was also omy is not favorable for some. Hence, in situ reported by Corrales et al. in their meta-analysis lasering with a thin laser fiber may be the best way and several other studies have identified older to tackle the stone and here disposable scopes patient age, patient comorbidities, renal abnor- have proven to be equal, if not better, than their malities, altered kidney function, pregnancy, his- more expensive reusable counterparts.18,19 In our tory of UTI, infectious stone disease, inadequate study, in situ dusting was the preferred means of antibiotic coverage, stone size, lower pole stones lithotripsy in Group 2, with lesser fragmentation and operative times, and intrarenal pressures and extraction than Group 1. (IRP), among several other factors as independ- ent contributing factors for septic complications FLEXOR had patients enrolled where RIRS was after RIRS.27–32 However, they did not recom- done in normal PCS only using both types of mend using a disposable scope to actually mini- scope. However, disposable scopes completely mize the risk of infective complications and hence negate the element of wear and tear and mainte- it remains debatable if disposable scope is indeed nance all together. Perhaps that’s why they are an independent risk factor for infective complica- the preferred choice by most surgeons when tions. In the overall cohort, an UAS was used in anticipating complex RIRS surgery20 and also in 99.62% of patients (Table 2), which might have anomalous kidneys. García Rojo et al.21 reported contributed to minimizing the risk of high IRP as that in 249 cases with renal anomalies (60.1%), a a significant attributing factor for post-op major disposable scope was used, and the global trend sepsis.28 was toward using smaller and disposable scopes. Female gender is also a well-established risk fac- Literature has mixed reports on the outcome with tor for infectious complications following some studies showing no significance difference22 RIRS.29,30 This was, however, not noted in our and some like Bozzini et al.11 reporting better out- study, with an equal gender distribution seen in comes with disposable scopes. Mazzucchi et al.23 both groups. In the Multivariate analysis (MVA) explained that a reduced deflection and an of our study, apart from type of scopes, the other impaired vision of a heavily used scope could con- significant contributing factors to overall compli- tribute to poorer SFR outcome for RIRS. SFR is cations were stone size, lower pole stones, and dependent on multiple factors, including stone operative times only. Reasonably, increased oper- volume, expertise, lasers used, and stone loca- ating time requires the use of a larger amount of tion.24 Our multivariate analysis reflected that irrigation volume when compared with shorter disposable scopes may contribute to minimizing procedures, and a higher stone burden would also RF and help improve the single-stage SFR. The necessitate more operative time, and this could Reducing Operative Complications from Kidney provide more nidus for infection.31 Yet these Stones (ROCKS) collaborative reported that in complications were not life threatening and tran- 1817 ureteroscopy procedures, 2.4% of patients sient and did not increase the hospitalization time were hospitalized secondary to infectious compli- with Group 2 having a significantly shorter hospi- cations.25 The Clinical Research Office of the tal stay. Endourology Society (CROES) evaluated 11,885 patients undergoing ureteroscopy (both semirigid The aforementioned findings indicate that per- and flexible for renal and ureteric stones) and haps earmarking the type of scope itself as an reported that postoperative fever occurred in independent risk factor for complications needs 1.8% of patients with 1.0% of patients developing further evaluation. Disposable scopes have been a urinary tract infection (UTI) and 0.3% of favored over reusables to minimize time, costs of patients becoming septic.26 In the MV analysis of sterilization, and proposed as a better alternative our study, disposable scope was associated with to minimize infective complications if reusables higher overall complications. However, when we are not sterilized well.9,32 Our study does not sup- analyze the implications closely, transient fever port this finding as similar profiles of infective needing only antibiotics was the most common complications were noted in both groups. Hence, journals.sagepub.com/home/tau 7 Therapeutic Advances in Urology Volume 15 we would suggest advocating or advertising the of RIRS as a modality will continue to increase use of a disposable scope to minimize infective world over,34–37 a new disposable scope each time complications, and if sterilization protocols are may just be the correct answer. safely followed, there is no reason that reusables should be considered inferior. Conclusion Our real-world practice observations suggest Limitation and strengths that urologists choose disposable scopes for big- The FLEXOR registry is likely the largest real- ger, lower pole, and harder stones, and it does world multinational multicenter study, but being indeed help in improving the single-stage SFR if a retrospective study, we were limited by our abil- used correctly with the appropriate lasers and ity to determine the clinical criteria on how a sur- lasing techniques in expert hands. We need geon decides on type, brand, and size of scope more information to make a resolute conclusion used. We lack the information on how many that the scope itself is an independent risk factor patients had infective stones aka stones in an for complications. With regard to costing, the infected system33 as well as preoperative stent urologists need to independently decide in their dwelling time and antibiotic protocols to provide ability to integrate disposable scope in their a detailed insight on cause and management of practice for the aforementioned study findings, sepsis. This further limits any subset analysis in based on the nuances of their respective health the patients who had sepsis. systems. Besides, from being a retrospective study, the main limitation of our study is the absence of Declarations cost analysis between the two cohorts. Being a global multi-center study across multiple health Ethics approval and consent to participate systems, a cost-analysis is not possible as pro- The study was approved by the ethics board of curement, price of scopes, and insurance dis- the Asian Institute of Nephrology and Urology, bursement vary across different geographical Hyderabad, India (#AINU 08/2022). Each insti- locations and various health centers. Yet this was tution obtained its own ethics board approval a study which had patients managed in a real- before contributing and provided anonymized world setting and helps shine light on global data. All patients provided signed informed con- practice patterns and preferences, as well as the sent to gather their anonymized data. bearing that has on surgical outcomes. We believe these data help urologists and industry partners Consent for publication to consider how best they can use this informa- Written informed consent for publication was tion to improve scope technology for maximum provided by the participants. operative outcomes in a single-stage RIRS espe- cially when dealing with bigger, harder stones in Author contributions different parts of the kidney. This also indirectly Vineet Gauhar: Conceptualization; Data cura- helps in providing data for better preoperative tion; Formal analysis; Writing – original draft. costing based on stone and patient clinical Chu Ann Chai: Writing – review & editing. parameters and to provide proof of concept to hospital management systems on why single-use Ben H Chew: Writing – review & editing. consumables should be integrated into daily Abhishek Singh: Writing – review & editing. RIRS practice. Daniele Castellani: Writing – review & editing. Having a good vision, excellent instrumentation Thomas Tailly: Writing – review & editing. with good flexibility, irrigation with and without instrument in the working channel, and a good Esteban Emiliani: Writing – review & editing. deflection to reach the desired calyx for proper William Ong Lay Keat: Writing – review & stone access is integral for minimizing the risk of editing. PCS injury, reducing the operative time, and yet Deepak Ragoori: Writing – review & editing. ensuring adequate stone disintegration with laser, all of which improves outcomes and minimizes Mohamed Amine Lakmichi: Writing – review preventable complications. Perhaps as the utility & editing. 8 journals.sagepub.com/home/tau V Gauhar, CA Chai et al. Jeremy Yuen-Chun Teoh: Writing – review & 6. Hosny K, Clark J and Srirangam SJ. Handling editing. and protecting your flexible ureteroscope: how to maximise scope usage. Transl Androl Urol 2019; Olivier Traxer: Writing – review & editing. 8(Suppl. 4): S426–S435. Bhaskar Kumar Somani: Writing – review & 7. Canales BK, Gleason JM, Hicks N, et al. editing. Independent analysis of Olympus flexible ureteroscope repairs. Urology 2007; 70: 11–15. Acknowledgements 8. Moore B, Proietti S, Giusti G, et al. Single-use None. ureteroscopes. Urol Clin North Am 2019; 46: 165–174. Funding 9. Scotland KB, Chan JYH and Chew BH. Single- The authors received no financial support for the use flexible ureteroscopes: how do they compare research, authorship, and/or publication of this with reusable ureteroscopes? J Endourol 2019; 33: article. 71–78. Competing interests 10. Ventimiglia E, Somani BK and Traxer O. The authors declared no potential conflicts of Flexible ureteroscopy: reuse? Or is single use the new direction? Curr Opin Urol 2020; 30: 113– interest with respect to the research, authorship, 119. and/or publication of this article. 11. Bozzini G, Filippi B, Alriyalat S, et al. Disposable Availability of data and materials versus reusable ureteroscopes: a prospective Due to the possibility of compromising the pri- multicenter randomized comparison. Res Rep Urol vacy of research participants, the data supporting 2021; 13: 63–71. this study are not publicly available. However, 12. Ofstead CL, Heymann OL, Quick MR, et al. they can be obtained from the corresponding The effectiveness of sterilization for flexible author B.K.S. at bhaskarsomani@yahoo.com ureteroscopes: a real-world study. Am J Infect upon reasonable request. Control 2017; 45: 888–895. 13. Deininger S, Haberstock L, Kruck S, et al. ORCID iD Single-use versus reusable ureterorenoscopes for Bhaskar Kumar Somani https://orcid.org/ retrograde intrarenal surgery (RIRS): systematic 0000-0002-6248-6478 comparative analysis of physical and optical properties in three different devices. World J Urol 2018; 36: 2059–2063. References 14. Sanguedolce F, Bozzini G, Chew B, et al. The 1. Turk C, Petřík A, Sarica K, et al. EAU guidelines evolving role of retrograde intrarenal surgery in on interventional treatment for urolithiasis. Eur the treatment of urolithiasis. Eur Urol Focus 2017; Urol 2016; 69: 475–482. 3: 46–55. 2. Assimos D, Krambeck A, Miller NL, et al. 15. Dale J, Kaplan AG, Radvak D, et al. Evaluation Surgical management of stones: American of a novel single-use flexible ureteroscope. J Urological Association/Endourological Society Endourol 2021; 35: 903–907. Guideline, PART I. J Urol 2016; 196: 1153– 16. Kramolowsky E, McDowell Z, Moore B, et al. 1160. Cost analysis of flexible ureteroscope repairs: 3. Taguchi K, Cho SY, Ng AC, et al. The evaluation of 655 procedures in a community- Urological Association of Asia clinical guideline based practice. J Endourol 2016; 30: 254–256. for urinary stone disease. Int J Urol 2019; 26: 17. Ozimek T, Cordes J, Wiessmeyer JR, et al. Steep 688–709. infundibulopelvic angle as a new risk factor for 4. Zhu M, Wang X, Shi Z, et al. Comparison flexible ureteroscope damage and complicated between retrograde intrarenal surgery and postoperative course. J Endourol 2018; 32: percutaneous nephrolithotripsy in the 597–602. management of renal stones: a meta-analysis. Exp 18. Eisel M, Strittmatter F, Ströbl S, et al. Ther Med 2019; 18: 1366–1374. Comparative investigation of reusable and 5. Quhal F and Seitz C. Guideline of the guidelines: single-use flexible endoscopes for urological urolithiasis. Curr Opin Urol 2021; 31: 125–129. interventions. Sci Rep 2020; 10: 5701. journals.sagepub.com/home/tau 9 Therapeutic Advances in Urology Volume 15 19. Patil A, Agrawal S, Singh A, et al. A single-center 28. Loftus C, Byrne M and Monga M. High pressure prospective comparative study of two single- endoscopic irrigation: impact on renal histology. use flexible ureteroscopes: LithoVue (Boston Int Braz J Urol 2021; 47: 350–356. Scientific, USA) and Uscope PU3022a (Zhuhai 29. Sun J, Xu J and OuYang J. Risk factors of Pusen, China). J Endourol 2021; 35: 274–278. infectious complications following ureteroscopy: 20. Dresner SL, Iremashvili V, Best SL, et al. a systematic review and meta-analysis. Urol Int Influence of lower pole infundibulopelvic angle 2020; 104: 113–124. on success of retrograde flexible ureteroscopy and 30. Chugh S, Pietropaolo A, Montanari E, et al. laser lithotripsy for the treatment of renal stones. Predictors of urinary infections and urosepsis J Endourol 2020; 34: 655–660. after ureteroscopy for stone disease: a systematic 21. García Rojo E, Teoh JY, Castellani D, et al. Real- review from EAU Section of Urolithiasis world global outcomes of retrograde intrarenal (EULIS). Curr Urol Rep 2020; 21: 16. surgery in anomalous kidneys: a high volume 31. Kim JW, Lee YJ, Chung J-W, et al. Clinical international multicenter study. Urology 2022; characteristics of postoperative febrile urinary 159: 41–47. tract infections after ureteroscopic lithotripsy. 22. Qi S, Yang E, Bao J, et al. Single-use versus Investig Clin Urol 2018; 59: 335–341. reusable digital flexible ureteroscopes for the treatment of renal calculi: a prospective 32. Corrales M, Sierra A, Doizi S, et al. Risk of sepsis multicenter randomized controlled trial. in retrograde intrarenal surgery: a systematic J Endourol 2020; 34: 18–24. review of the literature. Eur Urol Open Sci 2022; 44: 84–91. 23. Mazzucchi E, Marchini GS, Gabrigna Berto FC, et al. Single-use flexible ureteroscopes: update and 33. Khusid JA, Hordines JC, Sadiq AS, et al. perspective in developing countries. A narrative Prevention and management of infectious review. Int Braz J Urol 2022; 48: 456–467. complications of retrograde intrarenal surgery. Front Surg 2021; 8: 718583. 24. Zeng G, Zhao Z, Mazzon G, et al. European Association of Urology Section of Urolithiasis 34. Meng C, Peng L, Li J, et al. Comparison between and International Alliance of Urolithiasis joint single-use flexible ureteroscope and reusable consensus on retrograde intrarenal surgery for the flexible ureteroscope for upper urinary calculi: a management of renal stones. Eur Urol Focus 2022; systematic review and meta-analysis. Front Surg 8: 1461–1468. 2021; 8: 691170. 25. Cole A, Telang J, Kim T-K, et al. Infection- 35. Doizi S and Traxer O. Flexible ureteroscopy: related hospitalization following ureteroscopic technique, tips and tricks. Urolithiasis 2018; 46: stone treatment: results from a surgical 47–58. collaborative. BMC Urol 2020; 20: 176. 36. Wright AE, Rukin NJ and Somani BK. 26. de la Rosette J, Denstedt J, Geavlete P, et al. Ureteroscopy and stones: current status and The clinical research office of the endourological future expectations. World J Nephrol 2014; 3: society ureteroscopy global study: indications, 243–248. complications, and outcomes in 11,885 patients. 37. Dragos LB, Somani BK, Sener ET, et al. Which J Endourol 2014; 28: 131–139. Visit SAGE journals online flexible ureteroscopes (digital vs. fiber-optic) can journals.sagepub.com/ 27. De Coninck V, Keller EX, Rodríguez-Monsalve M, easily reach the difficult lower pole calices and have home/tau et al. Systematic review of ureteral access sheaths: better end-tip deflection: in vitro study on K-Box. A SAGE journals facts and myths. BJU Int 2018; 122: 959–969. PETRA evaluation. J Endourol 2017; 31: 630–637. 10 journals.sagepub.com/home/tau