RIRS with FV-UAS vs. ESWL for the management of 1–2-cm lower pole renal calculi in obese patients: a prospective study

RIRS with FV-UAS vs. ESWL for the management of 1–2-cm lower pole renal calculi in obese patients: a prospective study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article RIRS with FV-UAS vs. ESWL for the management of 1–2-cm lower pole renal calculi in obese patients: a prospective study Si-cong Zhang, Qing Wang, Jie Wu, Yun-Peng Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4730673/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective To evaluate the efficacy and safety of retrograde intrarenal surgery (RIRS) combined with fexible vacuum-assisted ureteral access sheath (FV-UAS) versus extracorporeal shock wave lithotripsy (ESWL) for the management of 1–2 cm lower pole renal calculi (LPC) in obese patients. Patients and methods This prospective, randomized study included 149 obese patients with 1-2 cm LPC. Patients were allocated into two groups: 76 patients underwent RIRS with FV-UAS, and 73 patients received ESWL.The parameters assessed included stone-free rate (SFR), retreatment rate, complications, operative time, and pain intensity measured by the Visual Analog Scale (VAS).Stone-free status was defined as the absence of stones on computed tomography or residual fragments smaller than 4 mm at 4 weeks post-procedure. Results The baseline characteristics of the two groups were comparable.The SFR was significantly higher in the RIRS group, reaching 86.8%, compared to 63.0% in the ESWL group (P = 0.034). Furthermore, the retreatment rate was significantly lower in the RIRS group, at 5.2%, versus 24.7% in the ESWL group (P < 0.001). The average operative time for RIRS was notably longer, at 65.3 ± 6.4 minutes, compared to 25.3 ± 7.8 minutes for ESWL (P < 0.001). The complication rates were 9.2% for the RIRS group and 6.8% for the ESWL group, with no statistically significant difference (P = 0.326). All complications were classified as Grade I or II according to the modified Clavien classification system. No significant differences were observed between the two groups regarding pain VAS scores and the composition of the stones. Conclusions RIRS with FV-UAS demonstrated superior efficacy, evidenced by a higher SFR and reduced retreatment rates compared to ESWL, despite a longer operative duration. Both treatment modalities showed comparable safety profiles. RIRS with FV-UAS emerges as a viable, effective, and reproducible intervention for managing 1-2 cm LPC in obese patients, providing significant clinical advantages. Health sciences/Diseases Health sciences/Urology Lower pole renal calculi Obesity Flexible ureteroscopy Extracorporeal shock wave lithotripsy Combination therapy Figures Figure 1 Figure 2 Introduction The World Health Organization defines obesity as having a body mass index (BMI) of 30 kg/m 2 or higher [ 1 ]. This condition represents a major global health issue, given its increasing prevalence and the numerous comorbidities linked to it, such as kidney stone disease (KSD).The management of kidney stones in obese patients presents unique challenges due to anatomical and physiological differences[ 2 ], which can impact the efficacy and safety of various treatment modalities. Lower pole renal calculi (LPC), a common type of kidney stone, are particularly challenging to treat due to their location within the kidney[ 3 ].ESWL and RIRS are frequently utilized minimally invasive methods for managing renal calculi [ 4 ].ESWL uses shock waves to break stones into smaller fragments[ 5 ], allowing them to be passed naturally. However, its effectiveness can be limited in obese patients due to the increased distance between the skin and the stone, and the lower effectiveness in treating LPC[ 6 ]. On the other hand, RIRS[ 7 ] involves the use of a flexible ureteroscope to directly visualize and fragment the stones, which can be more effective but also more technically demanding and time-consuming. Recent technological advancements, such as the flexible vacuum-assisted ureteral access sheath (FV-UAS), aim to enhance the outcomes of RIRS by aiding in the efficient removal of stone fragments and mitigating intrarenal pressure[ 8 ]. Despite these advancements, there is a paucity of comparative data on the efficacy and safety of RIRS with FV-UAS versus ESWL specifically in obese patients with LPC.In spite of these technological progressions, comprehensive comparative studies evaluating the effectiveness and safety of RIRS with FV-UAS versus ESWL in obese patients with LPC remain markedly insufficient. This study aims to evaluate and compare the efficacy and safety of RIRS combined with FV-UAS and ESWL for the management of 1–2 cm LPC in obese patients. By assessing key outcomes such as stone-free rate (SFR), retreatment rate, complications, operative time, and pain VAS score, this study seeks to provide insights into the most effective treatment approach for this patient population. Materials and methods Inclusion and Exclusion Criteria Inclusion criteria:1. Adult patients aged between 18 and 65 years; 2. Presence of lower pole renal calculi with a size ranging from 1 to 2 cm;3. Body mass index (BMI) exceeding 30 kg/m²;4.Normal renal function and anatomy of the renal tract. Exclusion criteria: 1. Uncontrollable urinary tract infections (UTI);2. Severe cardiovascular diseases, end-stage renal failure, or severe coagulation disorders;3.Pregnancy or presence of bilateral kidney stones;4. Prior history of ipsilateral extracorporeal shock wave lithotripsy (ESWL) or retrograde intrarenal surgery (RIRS). Randomization After patients completed informed consent forms, research workers at our center used a computer-generated random number coding table to allocate eligible patients. The sealed envelope held the random assignment. Participants and Preoperative preparation The study included 149 patients, 76 in the RIRS group and 73 in the ESWL group, based on power analysis performed to estimate the sample size(Fig. 1 ).Prior to the initiation of treatment, all participants underwent a thorough pre-treatment evaluation, which included the collection of demographic data, a detailed medical history, physical examination, routine laboratory investigations, and radiological assessments. Non-contrast computed tomography (CT) scans were employed to ascertain the characteristics of the renal calculi, with the stone size being defined by the maximum diameter of the calculi. ESWL and RIRS techniques An electromagnetic lithotripter (Dornier Lithotriptor S, Dornier MedTech GmbH, Germering, Germany) was utilized for all extracorporeal shock wave lithotripsy (ESWL) procedures, chosen for its proven effectiveness in renal calculi fragmentation. Energy levels for the shock waves were precisely controlled within a range of 12–14 kV. Each ESWL session involved the administration of up to 3000 shock waves, delivered at a frequency of 60–90 shocks per minute, until complete fragmentation of the renal calculi was achieved.Following each ESWL session, patients were scheduled for a follow-up evaluation one week later. This assessment included kidney, ureter, and bladder (KUB) radiographs as well as renal ultrasonography to evaluate the extent of stone fragmentation and detect any potential renal obstruction. In cases where stone fragmentation was deemed insufficient, additional ESWL sessions were performed. A maximum of three ESWL sessions were permitted per patient. If three sessions failed to achieve adequate stone breakage, patients were transitioned to alternative treatment modalities. The procedure for the FV-UAS group commenced with the administration of general anesthesia and positioning of patients in the lithotomy position to facilitate retrograde endoscopic access.Initial access to the ureter was achieved via the introduction of a Zebra guidewire using a rigid ureteroscope. Over this guidewire, an 11/13 Fr FV-UAS (36 cm for females, 46 cm for males) was advanced.A flexible ureteroscope was then utilized to identify renal calculi. The FV-UAS was then directed to the target calculus under fURS visualization, and stone fragmentation was performed using a 200 µm holmium laser fiber set at 0.4–0.6 J and a frequency of 30–40 Hz. Central negative pressure suction (85–90 cmH2O) ensured balanced fluid dynamics and clear visibility.Continuous suction of stone fragments was facilitated through the repeated insertion and withdrawal of the fURS, maintaining an irrigation flow rate of 80 mL/min. Upon concluding the fragmentation, the collecting system was reassessed for residual stone fragments, and both the FV-UAS and fURS were carefully withdrawn while monitoring for ureteral injuries(Fig. 2 ). A 6 Fr double-J stent was placed in each patient to maintain ureteral patency. In instances of severe ureteral stenosis or distortion, balloon dilation was attempted; if unsuccessful, a double-J stent was implanted to promote gradual ureteral dilation. Postoperative Evaluation The primary outcome measure was the stone-free rate (SFR), defined as the absence of detectable stones on imaging studies post-treatment. Secondary outcomes included the retreatment rate, incidence of complications, operative time, and pain assessment using the visual analog scale (VAS). Statistical analysis SPSS v.22.0 for Windows (IBM Corp., Armonk, NY, USA) was used for statistical analysis. Demographic characteristics, duration of follow-up, and clinical outcomes were compared between the two groups using the independent samples t-test; other clinical characteristics were compared between the two groups using the chi-square test. p < 0.05 was considered a significant difference. Results The study enrolled 160 eligible patients who were randomized into two groups: 80 patients in the RIRS group and 80 patients in the ESWL group. During the treatment and follow-up phase, 11 patients withdrew, resulting in 149 patients being analyzed for the primary outcome (Fig. 1 ). The demographic and clinical characteristics of the two groups were comparable, with no statistically significant differences observed(Table 1 ). Specifically, there were no notable differences in age, gender, and BMI. Additionally, the groups were matched in terms of medical history, including hypertension and diabetes, as well as stone burden, Hounsfield units, skin-to-stone distance, lower pole anatomy, stone location, and preoperative urine culture results(all P > 0.05). Table 1 Demographic and clinical characteristics Variables, mean ± SD or n (%) RIRS group(n = 76) ESWL group(n = 73) P BMI (kg/m 2 ) 32.7 ± 1.5 32.8 ± 1.4 0.640 Age(year) 49.2 ± 8.6 48.7 ± 9.0 0.730 Gender Male 30 (39.5%) 28 (38.4%) - Female 46 (60.5%) 45 (61.6%) 0.890 Hypertension history 10 (13.2%) 12 (16.4%) 0.475 Diabetes history 9 (14.5%) 10 (13.7%) 0.520 Mean stone size(mm) 15.4 ± 3.2 16.1 ± 3.4 0.275 Stone burden (mm 2 ) 231.5 ± 49.0 228.3 ± 48.7 0.693 Hounsfield units 980.45 ± 150.32 960.38 ± 145.27 0.310 Skin-to-stone distance(mm) 110.5 ± 14.9 110.9 ± 13.7 0.725 Lower-pole anatomy Infundibular-pelvic angle 49.5 ± 2.8 50.2 ± 3.1 0.320 Infundibular length (mm) 22.3 ± 2.1 23.1 ± 1.8 0.325 Infundibular width (mm) 5.8 ± 1.5 5.6 ± 1.3 0.680 Stone position Left side 31 (40.7%) 29 (39.7%) - Right side 45 (59.3%) 44 (60.3%) 0.290 Urine culture(positive) 6 (11.3%) 5 (8.6%) 0.365 BMI body mass index, SD standard deviation ,* P < 0.05, **P < 0.01 Table 2 summarizes the treatment and post-treatment data. The stone-free rate in the RIRS group was significantly higher compared to the ESWL group [86.8% vs. 63.0% (P = 0.034)]. The ESWL group exhibited a significantly higher retreatment rate due to the necessity for multiple sessions in 24.7% of patients (P < 0.001). Additionally, the mean operation time was notably longer in the RIRS group compared to the ESWL group (65.3 ± 6.4 vs. 25.3 ± 7.8 minutes, P < 0.001). The mean pain scores between the two groups were similar (4.1 ± 0.5 vs. 3.8 ± 0.4, P = 0.054). Postoperative complications were assessed using the modified Clavien classification system, revealing no significant difference in overall complication rates between the RIRS and ESWL groups (P > 0.05). Similarly, stone composition did not differ significantly between the two groups (P > 0.05). Table 2 Clinical outcomes and complications Variables, mean ± SD or n (%) RIRS group(n = 76) ESWL group(n = 73) P Operative time (min) 65.3 ± 6.4 25.3 ± 7.8 P < 0.001 Pain VAS score (range 1–10) 4.1 ± 0.5 3.8 ± 0.4 0.054 Total SFR at 4th week 66 (86.8) 46(63.0) 0.034 Retreatment rate 4(5.2) 18(24.7) P < 0.001 Complications 7(9.2) 5(6.8) 0.326 Modified Clavien classification Grade I 4 (5.3) 4 (5.4) - Grade II 3 (3.9) 1 (1.3) - Stone Analysis Uric acid 20 (26.3) 21 (28.8) 0.703 Calcium oxalate 42 (55.3) 39 (53.4) 0.845 Carboapatite 14 (18.4) 13 (17.8) 0.981 P < 0.05 is considered statistically significant; SD standard deviation, SFR stone-free rates Discussion Numerous cohort studies have substantiated that individuals classified as obese exhibit an elevated risk of developing kidney stone disease (KSD) [ 9 , 10 ]. The National Health and Nutrition Examination Survey (NHANES), a cross-sectional study, corroborated a higher prevalence of KSD among obese individuals compared to those of normal weight [ 11 , 12 ]. According to the European Association of Urology (EAU) guidelines, shock wave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL), and flexible ureteroscopy (fURS) are established standard therapeutic approaches for the management of renal calculi [ 13 ]. SWL operates by employing high-energy acoustic waves to externally fragment stone, thereby facilitating their expulsion through the urinary tract. Despite demonstrating lower stone-free rates (SFR) and necessitating higher retreatment rates, SWL remains a favored intervention due to its noninvasive nature and high acceptance among healthcare professionals and patients alike[ 14 ]. However, the success rate of SWL is significantly reduced in obese patients[ 15 ]. This attention in success rate is primarily attributed to factors such as increased skin to stone distance, which enhances shock wave absorption, composites in stone localization, and the radiolucency of urate stones, all of which affect the effective targeting of the shock wave beam.Additionally, an elevated BMI is associated with a heightened probability of residual stone fragments post SWL, compared to achieving a stone free status [ 16 ]. This association was further corroborated by Mezentsev, who documented a stone free rate of 73% in obese patients [ 17 ].A BMI exceeding 30 kg/m 2 is also correlated with an elevated risk of renal hematoma [ 18 ], potentially attributable to the inappropriate utilization of high-energy shock waves. Currently, a variety of minimally invasive techniques have demonstrated efficacy in managing LPC measuring between 10 to 20 mm. The feasibility of RIRS has been significantly augmented by ongoing advancements in flexible ureteroscopes (fURS), laser technology, and ureteral access sheaths. FURS is a minimally invasive endoscopic procedure that employs lasers to fragment kidney stones located within the urinary tract[ 19 ], theoretically circumventing the influence of obesity. Contemporary complication rates associated with fURS are approximately 9%, with severe complications (Clavien grade > III) comprising less than 1% [ 20 ]. In general, factors such as stone size, stone location, obesity, and the infundibulopelvic angle[ 21 ] affect the stone-free rate of stones. Intrarenal pressure (IRP) has consistently posed a significant challenge in RIRS[ 22 ]. While decreasing the fluid irrigation flow rate can help manage IRP, it often results in suboptimal intraoperative visualization. The FV-UAS[ 23 ] offers a solution by passively bending with the fURS to traverse the ureteropelvic junction (UPJ) and access the renal pelvis and calices.The FV-UAS facilitates free drainage of irrigation from the kidney, thereby improving vision and preventing potentially harmful elevations in IRP. According to the in vitro findings of Chen Y et al. [ 24 ], we calibrated the fluid irrigation flow rate to 80 mL/min and the negative pressure to 85–90 cmH 2 O, thereby maintaining IRP below 10 cmH 2 O. This configuration ensures the renal pelvis remains in a semi-saturated state, enhancing both visualization and procedural efficiency. Consequently, we have adopted a novel combination technique, integrating fURS with FV-UAS, to further enhance the treatment outcomes for LPC measuring 10–20 mm. This approach mitigates the risks traditionally associated with percutaneous renal surgery, including bleeding, pleural and visceral injuries, and urine leakage, while simultaneously providing a high SFR. In our study, the primary outcomes demonstrated a significantly higher SFR and a lower retreatment rate following RIRS, without a corresponding increase in complications when compared to the ESWL. Several factors elucidate these findings.Firstly, RIRS presents distinct advantages over ESWL, particularly due to the capability of laser energy in RIRS to fragment stones irrespective of their chemical composition or density. Furthermore, the FV-UAS in RIRS ensures direct entry into the target calculi. The suction generated by negative pressure through the FV-UAS enhances the removal of stone fragments, thereby improving the efficiency of the procedure.Conversely, the efficacy of ESWL is contingent upon several variables including patient obesity, stone density, chemical composition, and the skin-to-stone distance [ 25 , 26 ]. Notably, the SFR in RIRS is predominantly influenced by stone size, as indicated by Grasso and Ficazzola [ 27 ], who reported SFR of 82%, 71%, and 65% for stone sizes 2 cm respectively. However, the incidence of complications was higher after RIRS than after ESWL, reflecting the more invasive nature of RIRS. Nonetheless, this difference was not statistically significant, and the severity of complications, as classified by the modified Clavien system, remained comparable between both groups.All complications were manageable with medical treatment. There was no significant difference in pain perception among patients, although RIRS required a significantly longer surgical time compared to ESWL.These findings highlight the superior efficacy and effectiveness of RIRS in achieving higher stone-free rates and reducing the necessity for retreatment when compared to ESWL.This is achieved despite the longer procedural duration and similar complication profiles. This study does have some limitations that warrant acknowledgment. Firstly, the patient cohort consists solely of individuals with primary or secondary obesity, with no inclusion of cases of morbid obesity (BMI > 40 kg/m 2) . This constrains the applicability of our results to the wider population, particularly to individuals with more severe obesity.Secondly, the follow-up period was relatively short, which could potentially influence the long-term assessment of outcomes such as recurrence rates and long-term complications. A longer follow-up period would provide a more comprehensive understanding of the durability of the stone-free state and the overall effectiveness of the procedures.Thirdly, this was a single-center study characterized by a small sample size. The restricted number of participants may diminish the statistical power of the research and hinder the detection of subtle differences between the groups. Additionally, single-center data may not be representative of broader clinical practices and outcomes in different settings. Conclusion The study provides valuable insights into the comparative efficacy and safety of RIRS and ESWL, highlighting the superior stone-free rates and reduced retreatment rates associated with RIRS, alongside a comparable complication profile. Nevertheless, further research involving larger, multi-center cohorts with extended follow-up periods is necessary to validate these findings and to better understand the long-term benefits and risks associated with these treatment methods. Declarations Author contributions S-cZ: Writing – review & editing, Conceptualization. QW: Writing – original draft, Data curation. JW: Writing – Formal analysis. Y-pL: Writing – review & editing, Conceptualization. Funding This work was supported by the National Natural Science Foundation of China [82370781]. Data availability statement The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors. Conflict of interest All authors declare that they have no conflict of interest. Ethical approval This investigation is a prospective, controlled, single-center trial conducted from January 2021 to October 2023 at the Department of Urology, Affiliated Jiangning Hospital of Nanjing Medical University. The protocol for this trial has been accepted by the Chinese Clinical Trial Registry on 05/02/2020 (approval number: ChiCTR2200056402). All procedures performed in studies involving human participants were in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent The patients/participants provided their written informed consent to participate in this study. Corresponding author :Yun-Peng Li , E-mail: [email protected] . Department of Urology, Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing 211100, China. Author contributions S-cZ: Writing – review & editing, Conceptualization. QW: Writing – original draft, Data curation. JW: Writing – Formal analysis. Y-pL: Writing – review & editing, Conceptualization. Funding This work was supported by the National Natural Science Foundation of China [82370781]. Conflict of interest All authors declare that they have no conflict of interest. Data availability statement The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors. References Gallagher, Emily Jane et al. “The metabolic syndrome–from insulin resistance to obesity and diabetes.” The Medical clinics of North America vol. 95,5 (2011): 855–73. Sarica, Kemal. “Obesity and stones.” Current opinion in urology vol. 29,1 (2019): 27–32. Donaldson, James F et al. “Systematic review and meta-analysis of the clinical effectiveness of shock wave lithotripsy, retrograde intrarenal surgery, and percutaneous nephrolithotomy for lower-pole renal stones.” European urology vol. 67,4 (2015): 612–6. 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Ostergar, Adam et al. “Intrarenal Pressure with Vacuum-Assisted Ureteral Access Sheaths Using an In Situ Cadaveric Porcine Model.” Journal of endourology vol. 37,3 (2023): 353–357. Chen, Yujun et al. “Novel Flexible Vacuum-Assisted Ureteral Access Sheath Can Actively Control Intrarenal Pressure and Obtain a Complete Stone-Free Status.” Journal of endourology vol. 36,9 (2022): 1143–1148. Owen, Kevin et al. “Role of Noncontrast Computed Tomography Parameters in Predicting the Outcome of Extracorporeal Shock Wave Lithotripsy for Upper Urinary Stones Cases: A Meta-analysis.” Academic radiology, S1076-6332(23)00556-1. 18 Nov. 2023. El-Nahas, Ahmed R et al. “A prospective multivariate analysis of factors predicting stone disintegration by extracorporeal shock wave lithotripsy: the value of high-resolution noncontrast computed tomography.” European urology vol. 51,6 (2007): 1688-93; discussion 1693-4. Grasso, M, and M Ficazzola. “Retrograde ureteropyeloscopy for lower pole caliceal calculi.” The Journal of urology vol. 162,6 (1999): 1904–8. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4730673","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":338480454,"identity":"6fbd4568-9a69-4146-9f64-d377f3f74551","order_by":0,"name":"Si-cong Zhang","email":"","orcid":"","institution":"The Second Affiliated Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Si-cong","middleName":"","lastName":"Zhang","suffix":""},{"id":338480459,"identity":"ba58271b-429a-4311-937f-68b750918732","order_by":1,"name":"Qing Wang","email":"","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Qing","middleName":"","lastName":"Wang","suffix":""},{"id":338480465,"identity":"fcbf7878-b772-4bee-8b15-8461251dc10d","order_by":2,"name":"Jie Wu","email":"","orcid":"","institution":"Nanjing First Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Wu","suffix":""},{"id":338480467,"identity":"eec33ff6-7c8c-4efa-9ea6-ce0d65ac1d05","order_by":3,"name":"Yun-Peng Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAx0lEQVRIiWNgGAWjYBACfvbmgw8SeCSY2dgbiNQi2XMs2eCBjAU7H88BIrUY3Mgxk3xgU8EvJ5FArJYDaQkSCTkS0mySjzfeYKixiSbssAOHDxgknJEwZpNOK7ZgOJaW20BIC9/BtoSExB6JZDbpHDMJxobDhLUwHOYxOJD4T6K+TfIMkVoEjvEYNoADWYKHSC2SPWzJDGAtPEC/JBDjF375x8d//uCpY5ZvP7zxxocaGyL8ggQMiI4aJC2k6hgFo2AUjIKRAQCy/jwAUZyFWwAAAABJRU5ErkJggg==","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":true,"prefix":"","firstName":"Yun-Peng","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2024-07-12 13:38:35","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4730673/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4730673/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":63313557,"identity":"eae771e6-2e35-43c1-8868-7c1734198d5d","added_by":"auto","created_at":"2024-08-26 20:57:09","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":309767,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4730673/v1/ddc7fc95736b767eaa78f7dd.jpg"},{"id":63313558,"identity":"c16800ce-754f-41b6-bcf0-96edb9dd567f","added_by":"auto","created_at":"2024-08-26 20:57:10","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":132049,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4730673/v1/ff7e7c2bdd16792fc5e6fa11.jpg"},{"id":68843173,"identity":"0c12bdc3-45d0-4ff4-991f-d3aacb063461","added_by":"auto","created_at":"2024-11-12 15:24:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":893272,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4730673/v1/76df112e-ffc9-4b24-9238-acc70e71748c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"RIRS with FV-UAS vs. ESWL for the management of 1–2-cm lower pole renal calculi in obese patients: a prospective study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe World Health Organization defines obesity as having a body mass index (BMI) of 30 kg/m\u003csup\u003e2\u003c/sup\u003e or higher [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. This condition represents a major global health issue, given its increasing prevalence and the numerous comorbidities linked to it, such as kidney stone disease (KSD).The management of kidney stones in obese patients presents unique challenges due to anatomical and physiological differences[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], which can impact the efficacy and safety of various treatment modalities.\u003c/p\u003e \u003cp\u003eLower pole renal calculi (LPC), a common type of kidney stone, are particularly challenging to treat due to their location within the kidney[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].ESWL and RIRS are frequently utilized minimally invasive methods for managing renal calculi [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].ESWL uses shock waves to break stones into smaller fragments[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], allowing them to be passed naturally. However, its effectiveness can be limited in obese patients due to the increased distance between the skin and the stone, and the lower effectiveness in treating LPC[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. On the other hand, RIRS[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] involves the use of a flexible ureteroscope to directly visualize and fragment the stones, which can be more effective but also more technically demanding and time-consuming.\u003c/p\u003e \u003cp\u003eRecent technological advancements, such as the flexible vacuum-assisted ureteral access sheath (FV-UAS), aim to enhance the outcomes of RIRS by aiding in the efficient removal of stone fragments and mitigating intrarenal pressure[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Despite these advancements, there is a paucity of comparative data on the efficacy and safety of RIRS with FV-UAS versus ESWL specifically in obese patients with LPC.In spite of these technological progressions, comprehensive comparative studies evaluating the effectiveness and safety of RIRS with FV-UAS versus ESWL in obese patients with LPC remain markedly insufficient.\u003c/p\u003e \u003cp\u003eThis study aims to evaluate and compare the efficacy and safety of RIRS combined with FV-UAS and ESWL for the management of 1\u0026ndash;2 cm LPC in obese patients. By assessing key outcomes such as stone-free rate (SFR), retreatment rate, complications, operative time, and pain VAS score, this study seeks to provide insights into the most effective treatment approach for this patient population.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eInclusion and Exclusion Criteria\u003c/h2\u003e \u003cp\u003eInclusion criteria:1. Adult patients aged between 18 and 65 years; 2. Presence of lower pole renal calculi with a size ranging from 1 to 2 cm;3. Body mass index (BMI) exceeding 30 kg/m\u0026sup2;;4.Normal renal function and anatomy of the renal tract.\u003c/p\u003e \u003cp\u003eExclusion criteria: 1. Uncontrollable urinary tract infections (UTI);2. Severe cardiovascular diseases, end-stage renal failure, or severe coagulation disorders;3.Pregnancy or presence of bilateral kidney stones;4. Prior history of ipsilateral extracorporeal shock wave lithotripsy (ESWL) or retrograde intrarenal surgery (RIRS).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eRandomization\u003c/h2\u003e \u003cp\u003eAfter patients completed informed consent forms, research workers at our center used a computer-generated random number coding table to allocate eligible patients. The sealed envelope held the random assignment.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eParticipants and Preoperative preparation\u003c/h2\u003e \u003cp\u003eThe study included 149 patients, 76 in the RIRS group and 73 in the ESWL group, based on power analysis performed to estimate the sample size(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).Prior to the initiation of treatment, all participants underwent a thorough pre-treatment evaluation, which included the collection of demographic data, a detailed medical history, physical examination, routine laboratory investigations, and radiological assessments. Non-contrast computed tomography (CT) scans were employed to ascertain the characteristics of the renal calculi, with the stone size being defined by the maximum diameter of the calculi.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eESWL and RIRS techniques\u003c/h2\u003e \u003cp\u003eAn electromagnetic lithotripter (Dornier Lithotriptor S, Dornier MedTech GmbH, Germering, Germany) was utilized for all extracorporeal shock wave lithotripsy (ESWL) procedures, chosen for its proven effectiveness in renal calculi fragmentation. Energy levels for the shock waves were precisely controlled within a range of 12\u0026ndash;14 kV. Each ESWL session involved the administration of up to 3000 shock waves, delivered at a frequency of 60\u0026ndash;90 shocks per minute, until complete fragmentation of the renal calculi was achieved.Following each ESWL session, patients were scheduled for a follow-up evaluation one week later. This assessment included kidney, ureter, and bladder (KUB) radiographs as well as renal ultrasonography to evaluate the extent of stone fragmentation and detect any potential renal obstruction. In cases where stone fragmentation was deemed insufficient, additional ESWL sessions were performed. A maximum of three ESWL sessions were permitted per patient. If three sessions failed to achieve adequate stone breakage, patients were transitioned to alternative treatment modalities.\u003c/p\u003e \u003cp\u003eThe procedure for the FV-UAS group commenced with the administration of general anesthesia and positioning of patients in the lithotomy position to facilitate retrograde endoscopic access.Initial access to the ureter was achieved via the introduction of a Zebra guidewire using a rigid ureteroscope. Over this guidewire, an 11/13 Fr FV-UAS (36 cm for females, 46 cm for males) was advanced.A flexible ureteroscope was then utilized to identify renal calculi. The FV-UAS was then directed to the target calculus under fURS visualization, and stone fragmentation was performed using a 200 \u0026micro;m holmium laser fiber set at 0.4\u0026ndash;0.6 J and a frequency of 30\u0026ndash;40 Hz. Central negative pressure suction (85\u0026ndash;90 cmH2O) ensured balanced fluid dynamics and clear visibility.Continuous suction of stone fragments was facilitated through the repeated insertion and withdrawal of the fURS, maintaining an irrigation flow rate of 80 mL/min. Upon concluding the fragmentation, the collecting system was reassessed for residual stone fragments, and both the FV-UAS and fURS were carefully withdrawn while monitoring for ureteral injuries(Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). A 6 Fr double-J stent was placed in each patient to maintain ureteral patency. In instances of severe ureteral stenosis or distortion, balloon dilation was attempted; if unsuccessful, a double-J stent was implanted to promote gradual ureteral dilation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative Evaluation\u003c/h2\u003e \u003cp\u003eThe primary outcome measure was the stone-free rate (SFR), defined as the absence of detectable stones on imaging studies post-treatment. Secondary outcomes included the retreatment rate, incidence of complications, operative time, and pain assessment using the visual analog scale (VAS).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eSPSS v.22.0 for Windows (IBM Corp., Armonk, NY, USA) was used for statistical analysis. Demographic characteristics, duration of follow-up, and clinical outcomes were compared between the two groups using the independent samples t-test; other clinical characteristics were compared between the two groups using the chi-square test. p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered a significant difference.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe study enrolled 160 eligible patients who were randomized into two groups: 80 patients in the RIRS group and 80 patients in the ESWL group. During the treatment and follow-up phase, 11 patients withdrew, resulting in 149 patients being analyzed for the primary outcome (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe demographic and clinical characteristics of the two groups were comparable, with no statistically significant differences observed(Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Specifically, there were no notable differences in age, gender, and BMI. Additionally, the groups were matched in terms of medical history, including hypertension and diabetes, as well as stone burden, Hounsfield units, skin-to-stone distance, lower pole anatomy, stone location, and preoperative urine culture results(all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic and clinical characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRIRS group(n\u0026thinsp;=\u0026thinsp;76)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eESWL group(n\u0026thinsp;=\u0026thinsp;73)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.640\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge(year)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48.7\u0026thinsp;\u0026plusmn;\u0026thinsp;9.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.730\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30 (39.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28 (38.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46 (60.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45 (61.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.890\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHypertension history\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (13.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (16.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.475\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes history\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (14.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10 (13.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.520\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean stone size(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.275\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStone burden (mm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e231.5\u0026thinsp;\u0026plusmn;\u0026thinsp;49.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e228.3\u0026thinsp;\u0026plusmn;\u0026thinsp;48.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.693\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHounsfield units\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e980.45\u0026thinsp;\u0026plusmn;\u0026thinsp;150.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e960.38\u0026thinsp;\u0026plusmn;\u0026thinsp;145.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.310\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSkin-to-stone distance(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e110.5\u0026thinsp;\u0026plusmn;\u0026thinsp;14.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e110.9\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.725\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLower-pole anatomy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfundibular-pelvic angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.320\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfundibular length (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.325\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfundibular width (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.680\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStone position\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeft side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31 (40.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29 (39.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e45 (59.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44 (60.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.290\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUrine culture(positive)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (11.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (8.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.365\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eBMI body mass index, SD standard deviation ,* P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, **P\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e summarizes the treatment and post-treatment data. The stone-free rate in the RIRS group was significantly higher compared to the ESWL group [86.8% vs. 63.0% (P\u0026thinsp;=\u0026thinsp;0.034)]. The ESWL group exhibited a significantly higher retreatment rate due to the necessity for multiple sessions in 24.7% of patients (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Additionally, the mean operation time was notably longer in the RIRS group compared to the ESWL group (65.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4 vs. 25.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8 minutes, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The mean pain scores between the two groups were similar (4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 vs. 3.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4, P\u0026thinsp;=\u0026thinsp;0.054). Postoperative complications were assessed using the modified Clavien classification system, revealing no significant difference in overall complication rates between the RIRS and ESWL groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Similarly, stone composition did not differ significantly between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical outcomes and complications\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRIRS group(n\u0026thinsp;=\u0026thinsp;76)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eESWL group(n\u0026thinsp;=\u0026thinsp;73)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOperative time (min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePain VAS score (range 1\u0026ndash;10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.054\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal SFR at 4th week\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66 (86.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46(63.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.034\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRetreatment rate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4(5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18(24.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7(9.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5(6.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.326\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModified Clavien classification\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade I\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (5.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (5.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (3.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStone Analysis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUric acid\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20 (26.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21 (28.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.703\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalcium oxalate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42 (55.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39 (53.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.845\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarboapatite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (18.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13 (17.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.981\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;0.05 is considered statistically significant; SD standard deviation, SFR stone-free rates\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eNumerous cohort studies have substantiated that individuals classified as obese exhibit an elevated risk of developing kidney stone disease (KSD) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The National Health and Nutrition Examination Survey (NHANES), a cross-sectional study, corroborated a higher prevalence of KSD among obese individuals compared to those of normal weight [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. According to the European Association of Urology (EAU) guidelines, shock wave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL), and flexible ureteroscopy (fURS) are established standard therapeutic approaches for the management of renal calculi [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. SWL operates by employing high-energy acoustic waves to externally fragment stone, thereby facilitating their expulsion through the urinary tract. Despite demonstrating lower stone-free rates (SFR) and necessitating higher retreatment rates, SWL remains a favored intervention due to its noninvasive nature and high acceptance among healthcare professionals and patients alike[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, the success rate of SWL is significantly reduced in obese patients[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This attention in success rate is primarily attributed to factors such as increased skin to stone distance, which enhances shock wave absorption, composites in stone localization, and the radiolucency of urate stones, all of which affect the effective targeting of the shock wave beam.Additionally, an elevated BMI is associated with a heightened probability of residual stone fragments post SWL, compared to achieving a stone free status [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This association was further corroborated by Mezentsev, who documented a stone free rate of 73% in obese patients [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].A BMI exceeding 30 kg/m\u003csup\u003e2\u003c/sup\u003e is also correlated with an elevated risk of renal hematoma [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], potentially attributable to the inappropriate utilization of high-energy shock waves.\u003c/p\u003e \u003cp\u003eCurrently, a variety of minimally invasive techniques have demonstrated efficacy in managing LPC measuring between 10 to 20 mm. The feasibility of RIRS has been significantly augmented by ongoing advancements in flexible ureteroscopes (fURS), laser technology, and ureteral access sheaths. FURS is a minimally invasive endoscopic procedure that employs lasers to fragment kidney stones located within the urinary tract[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], theoretically circumventing the influence of obesity. Contemporary complication rates associated with fURS are approximately 9%, with severe complications (Clavien grade\u0026thinsp;\u0026gt;\u0026thinsp;III) comprising less than 1% [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn general, factors such as stone size, stone location, obesity, and the infundibulopelvic angle[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] affect the stone-free rate of stones. Intrarenal pressure (IRP) has consistently posed a significant challenge in RIRS[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. While decreasing the fluid irrigation flow rate can help manage IRP, it often results in suboptimal intraoperative visualization. The FV-UAS[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] offers a solution by passively bending with the fURS to traverse the ureteropelvic junction (UPJ) and access the renal pelvis and calices.The FV-UAS facilitates free drainage of irrigation from the kidney, thereby improving vision and preventing potentially harmful elevations in IRP. According to the in vitro findings of Chen Y et al. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], we calibrated the fluid irrigation flow rate to 80 mL/min and the negative pressure to 85\u0026ndash;90 cmH\u003csub\u003e2\u003c/sub\u003eO, thereby maintaining IRP below 10 cmH\u003csub\u003e2\u003c/sub\u003eO. This configuration ensures the renal pelvis remains in a semi-saturated state, enhancing both visualization and procedural efficiency. Consequently, we have adopted a novel combination technique, integrating fURS with FV-UAS, to further enhance the treatment outcomes for LPC measuring 10\u0026ndash;20 mm. This approach mitigates the risks traditionally associated with percutaneous renal surgery, including bleeding, pleural and visceral injuries, and urine leakage, while simultaneously providing a high SFR.\u003c/p\u003e \u003cp\u003eIn our study, the primary outcomes demonstrated a significantly higher SFR and a lower retreatment rate following RIRS, without a corresponding increase in complications when compared to the ESWL. Several factors elucidate these findings.Firstly, RIRS presents distinct advantages over ESWL, particularly due to the capability of laser energy in RIRS to fragment stones irrespective of their chemical composition or density. Furthermore, the FV-UAS in RIRS ensures direct entry into the target calculi. The suction generated by negative pressure through the FV-UAS enhances the removal of stone fragments, thereby improving the efficiency of the procedure.Conversely, the efficacy of ESWL is contingent upon several variables including patient obesity, stone density, chemical composition, and the skin-to-stone distance [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Notably, the SFR in RIRS is predominantly influenced by stone size, as indicated by Grasso and Ficazzola [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], who reported SFR of 82%, 71%, and 65% for stone sizes\u0026thinsp;\u0026lt;\u0026thinsp;1 cm, 1\u0026ndash;2 cm, and \u0026gt;\u0026thinsp;2 cm respectively.\u003c/p\u003e \u003cp\u003eHowever, the incidence of complications was higher after RIRS than after ESWL, reflecting the more invasive nature of RIRS. Nonetheless, this difference was not statistically significant, and the severity of complications, as classified by the modified Clavien system, remained comparable between both groups.All complications were manageable with medical treatment. There was no significant difference in pain perception among patients, although RIRS required a significantly longer surgical time compared to ESWL.These findings highlight the superior efficacy and effectiveness of RIRS in achieving higher stone-free rates and reducing the necessity for retreatment when compared to ESWL.This is achieved despite the longer procedural duration and similar complication profiles.\u003c/p\u003e \u003cp\u003eThis study does have some limitations that warrant acknowledgment. Firstly, the patient cohort consists solely of individuals with primary or secondary obesity, with no inclusion of cases of morbid obesity (BMI\u0026thinsp;\u0026gt;\u0026thinsp;40 kg/m\u003csup\u003e2)\u003c/sup\u003e. This constrains the applicability of our results to the wider population, particularly to individuals with more severe obesity.Secondly, the follow-up period was relatively short, which could potentially influence the long-term assessment of outcomes such as recurrence rates and long-term complications. A longer follow-up period would provide a more comprehensive understanding of the durability of the stone-free state and the overall effectiveness of the procedures.Thirdly, this was a single-center study characterized by a small sample size. The restricted number of participants may diminish the statistical power of the research and hinder the detection of subtle differences between the groups. Additionally, single-center data may not be representative of broader clinical practices and outcomes in different settings.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe study provides valuable insights into the comparative efficacy and safety of RIRS and ESWL, highlighting the superior stone-free rates and reduced retreatment rates associated with RIRS, alongside a comparable complication profile. Nevertheless, further research involving larger, multi-center cohorts with extended follow-up periods is necessary to validate these findings and to better understand the long-term benefits and risks associated with these treatment methods.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eS-cZ: Writing \u0026ndash; review \u0026amp; editing, Conceptualization. QW: Writing \u0026ndash; original draft, Data curation. JW: Writing \u0026ndash; Formal analysis. Y-pL: Writing \u0026ndash; review \u0026amp; editing, Conceptualization.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Natural Science Foundation of China [82370781].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u0026nbsp;\u003c/strong\u003eAll authors declare that they have no conflict of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e This investigation is a prospective, controlled, single-center trial conducted from January 2021 to October 2023 at the Department of Urology, Affiliated Jiangning Hospital of Nanjing Medical University. The protocol for this trial has been accepted by the Chinese Clinical Trial Registry on 05/02/2020 (approval number: ChiCTR2200056402). All procedures performed in studies involving human participants were in accordance with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent\u0026nbsp;\u003c/strong\u003eThe patients/participants provided their written informed consent to participate in this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author\u003c/strong\u003e:Yun-Peng Li , E-mail:[email protected]. Department of Urology, Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing 211100, China.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eS-cZ: Writing \u0026ndash; review \u0026amp; editing, Conceptualization. QW: Writing \u0026ndash; original draft, Data curation. JW: Writing \u0026ndash; Formal analysis. Y-pL: Writing \u0026ndash; review \u0026amp; editing, Conceptualization.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Natural Science Foundation of China [82370781].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u0026nbsp;\u003c/strong\u003eAll authors declare that they have no conflict of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGallagher, Emily Jane et al. \u0026ldquo;The metabolic syndrome\u0026ndash;from insulin resistance to obesity and diabetes.\u0026rdquo; The Medical clinics of North America vol. 95,5 (2011): 855\u0026ndash;73.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSarica, Kemal. \u0026ldquo;Obesity and stones.\u0026rdquo; Current opinion in urology vol. 29,1 (2019): 27\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDonaldson, James F et al. \u0026ldquo;Systematic review and meta-analysis of the clinical effectiveness of shock wave lithotripsy, retrograde intrarenal surgery, and percutaneous nephrolithotomy for lower-pole renal stones.\u0026rdquo; European urology vol. 67,4 (2015): 612\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSrisubat, Attasit et al. \u0026ldquo;Extracorporeal shock wave lithotripsy (ESWL) versus percutaneous nephrolithotomy (PCNL) or retrograde intrarenal surgery (RIRS) for kidney stones.\u0026rdquo; The Cochrane database of systematic reviews,11 CD007044. 24 Nov. 2014.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKachkoul, R et al. \u0026ldquo;Urolithiasis: History, epidemiology, aetiologic factors and management.\u0026rdquo; The Malaysian journal of pathology vol. 45,3 (2023): 333\u0026ndash;352.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlmeras, C et al. \u0026ldquo;2022 Recommendations of the AFU Lithiasis Committee: Extracorporeal shock wave lithotripsy (ESWL).\u0026rdquo; Progres en urologie: journal de l'Association francaise d'urologie et de la Societe francaise d'urologie vol. 33,14 (2023): 812\u0026ndash;824.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eT\u0026uuml;rk, Christian et al. \u0026ldquo;EAU Guidelines on Interventional Treatment for Urolithiasis.\u0026rdquo; European urology vol. 69,3 (2016): 475\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, Du-Jian et al. \u0026ldquo;RIRS with FV-UAS vs. MPCNL for 2-3-cm upper urinary tract stones: a prospective study.\u0026rdquo; Urolithiasis vol. 52,1 31. 10 Feb. 2024.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAune, Dagfinn et al. \u0026ldquo;Body fatness, diabetes, physical activity and risk of kidney stones: a systematic review and meta-analysis of cohort studies.\u0026rdquo; European journal of epidemiology vol. 33,11 (2018): 1033\u0026ndash;1047.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHess, Bernhard. \u0026ldquo;Metabolic syndrome, obesity and kidney stones.\u0026rdquo; Arab journal of urology vol. 10,3 (2012): 258\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbufaraj, Mohammad et al. \u0026ldquo;Prevalence and Trends in Kidney Stone Among Adults in the USA: Analyses of National Health and Nutrition Examination Survey 2007\u0026ndash;2018 Data.\u0026rdquo; European urology focus vol. 7,6 (2021): 1468\u0026ndash;1475.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDomingos, Fernando, and Adelaide Serra. \u0026ldquo;Nephrolithiasis is associated with an increased prevalence of cardiovascular disease.\u0026rdquo; Nephrology, dialysis, transplantation: official publication of the European Dialysis and Transplant Association - European Renal Association vol. 26,3 (2011): 864\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGeraghty, Robert M et al. \u0026ldquo;Best Practice in Interventional Management of Urolithiasis: An Update from the European Association of Urology Guidelines Panel for Urolithiasis 2022.\u0026rdquo; European urology focus vol. 9,1 (2023): 199\u0026ndash;208.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKelly, Claire et al. \u0026ldquo;Nephrolithiasis in the Obese Patient.\u0026rdquo; Current urology reports vol. 20,7 36. 18 May. 2019.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDede, Onur et al. \u0026ldquo;Does morbid obesity influence the success and complication rates of extracorporeal shockwave lithotripsy for upper ureteral stones?.\u0026rdquo; Turkish journal of urology vol. 41,1 (2015): 20\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKroczak, Tadeusz et al. \u0026ldquo;Shockwave lithotripsy: techniques for improving outcomes.\u0026rdquo; World journal of urology vol. 35,9 (2017): 1341\u0026ndash;1346.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMezentsev, V A. \u0026ldquo;Extracorporeal shock wave lithotripsy in the treatment of renal pelvicalyceal stones in morbidly obese patients.\u0026rdquo; International braz j urol: official journal of the Brazilian Society of Urology vol. 31,2 (2005): 105\u0026ndash;10.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee, Shaun Wen-Huey et al. \u0026ldquo;Comparative effectiveness and safety of various treatment procedures for lower pole renal calculi: a systematic review and network meta-analysis.\u0026rdquo; BJU international vol. 116,2 (2015): 252\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDoizi, Steeve, and Olivier Traxer. \u0026ldquo;Flexible ureteroscopy: technique, tips and tricks.\u0026rdquo; Urolithiasis vol. 46,1 (2018): 47\u0026ndash;58.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrad\u0026egrave;re, Benjamin et al. \u0026ldquo;Evaluation of Guidelines for Surgical Management of Urolithiasis.\u0026rdquo; The Journal of urology vol. 199,5 (2018): 1267\u0026ndash;1271.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGeavlete, Bogdan et al. \u0026ldquo;Unfavorable factors in accessing the pelvicalyceal system during retrograde flexible ureteroscopy (fURS).\u0026rdquo; Journal of medicine and life vol. 16,3 (2023): 372\u0026ndash;380.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTokas, Theodoros et al. \u0026ldquo;Pressure matters: intrarenal pressures during normal and pathological conditions, and impact of increased values to renal physiology.\u0026rdquo; World journal of urology vol. 37,1 (2019): 125\u0026ndash;131.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOstergar, Adam et al. \u0026ldquo;Intrarenal Pressure with Vacuum-Assisted Ureteral Access Sheaths Using an In Situ Cadaveric Porcine Model.\u0026rdquo; Journal of endourology vol. 37,3 (2023): 353\u0026ndash;357.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen, Yujun et al. \u0026ldquo;Novel Flexible Vacuum-Assisted Ureteral Access Sheath Can Actively Control Intrarenal Pressure and Obtain a Complete Stone-Free Status.\u0026rdquo; Journal of endourology vol. 36,9 (2022): 1143\u0026ndash;1148.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOwen, Kevin et al. \u0026ldquo;Role of Noncontrast Computed Tomography Parameters in Predicting the Outcome of Extracorporeal Shock Wave Lithotripsy for Upper Urinary Stones Cases: A Meta-analysis.\u0026rdquo; Academic radiology, S1076-6332(23)00556-1. 18 Nov. 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEl-Nahas, Ahmed R et al. \u0026ldquo;A prospective multivariate analysis of factors predicting stone disintegration by extracorporeal shock wave lithotripsy: the value of high-resolution noncontrast computed tomography.\u0026rdquo; European urology vol. 51,6 (2007): 1688-93; discussion 1693-4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGrasso, M, and M Ficazzola. \u0026ldquo;Retrograde ureteropyeloscopy for lower pole caliceal calculi.\u0026rdquo; The Journal of urology vol. 162,6 (1999): 1904\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Lower pole renal calculi, Obesity, Flexible ureteroscopy, Extracorporeal shock wave lithotripsy, Combination therapy","lastPublishedDoi":"10.21203/rs.3.rs-4730673/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4730673/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo evaluate the efficacy and safety of retrograde intrarenal surgery (RIRS) combined with fexible vacuum-assisted ureteral access sheath (FV-UAS) versus extracorporeal shock wave lithotripsy (ESWL) for the management of 1–2 cm lower pole renal calculi (LPC) in obese patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatients and methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis prospective, randomized study included 149 obese patients with 1-2 cm LPC. Patients were allocated into two groups: 76 patients underwent RIRS with FV-UAS, and 73 patients received ESWL.The parameters assessed included stone-free rate (SFR), retreatment rate, complications, operative time, and pain intensity measured by the Visual Analog Scale (VAS).Stone-free status was defined as the absence of stones on computed tomography or residual fragments smaller than 4 mm at 4 weeks post-procedure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe baseline characteristics of the two groups were comparable.The SFR was significantly higher in the RIRS group, reaching 86.8%, compared to 63.0% in the ESWL group (P = 0.034). Furthermore, the retreatment rate was significantly lower in the RIRS group, at 5.2%, versus 24.7% in the ESWL group (P \u0026lt; 0.001). The average operative time for RIRS was notably longer, at 65.3 ± 6.4 minutes, compared to 25.3 ± 7.8 minutes for ESWL (P \u0026lt; 0.001). The complication rates were 9.2% for the RIRS group and 6.8% for the ESWL group, with no statistically significant difference (P = 0.326). All complications were classified as Grade I or II according to the modified Clavien classification system. No significant differences were observed between the two groups regarding pain VAS scores and the composition of the stones.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRIRS with FV-UAS demonstrated superior efficacy, evidenced by a higher SFR and reduced retreatment rates compared to ESWL, despite a longer operative duration. Both treatment modalities showed comparable safety profiles. RIRS with FV-UAS emerges as a viable, effective, and reproducible intervention for managing 1-2 cm LPC in obese patients, providing significant clinical advantages.\u003c/p\u003e","manuscriptTitle":"RIRS with FV-UAS vs. ESWL for the management of 1–2-cm lower pole renal calculi in obese patients: a prospective study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-26 20:57:05","doi":"10.21203/rs.3.rs-4730673/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9d9f0e71-159e-47aa-8f8e-40737028266e","owner":[],"postedDate":"August 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":35861574,"name":"Health sciences/Diseases"},{"id":35861575,"name":"Health sciences/Urology"}],"tags":[],"updatedAt":"2024-11-12T15:23:53+00:00","versionOfRecord":[],"versionCreatedAt":"2024-08-26 20:57:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4730673","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4730673","identity":"rs-4730673","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}