Comparison of clinical outcomes between metallic and polymeric ureteral stents in malignant ureteral obstruction: A retrospective comparative study

Comparison of clinical outcomes between metallic and polymeric ureteral stents in malignant ureteral obstruction: A retrospective comparative 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 Research Article Comparison of clinical outcomes between metallic and polymeric ureteral stents in malignant ureteral obstruction: A retrospective comparative study Tomohiro Nishi, Ryuto Nakazawa, Yuki Morimoto, Ryuji Yamada, Hikaru Tsukada, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8218264/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Jan, 2026 Read the published version in BMC Urology → Version 1 posted 12 You are reading this latest preprint version Abstract Background: The present study compared the clinical outcomes and indications of metallic ureteral stents (MS) and polymeric ureteral stents (PS) in patients with malignant ureteral obstruction (MUO). Methods: We analyzed 148 patients (240 ureters) with MUO who underwent ureteral stent placement at our Department of Urology between December 2014 and April 2022. The cohort included 67 patients (112 ureters) who received metallic stents (MS group) and 81 patients (128 ureters) who received polymeric stents (PS group). We evaluated overall survival and the primary underlying malignancies, and compared operative times, ureteral stent patency rates, and factors associated with stent obstruction between the two groups. Results: The one-year overall survival rate of patients with MUO was 27.2%, with a median survival time of 209 days. The main primary malignancies were gynecologic and gastrointestinal cancers, most commonly cervical, gastric, colorectal, breast, and ovarian cancers, in that order. The operative time for stent insertion was significantly longer in the MS group than in the PS group for both bilateral (p=0.0004) and unilateral (p=0.0094) placements. The one-year stent patency rate was significantly higher in the MS group (62.0%) than in the PS group (48.5%) (p=0.0144). Factors associated with stent obstruction included lower ureteral obstruction (p=0.0401), direct tumor compression (p=0.0172), pyuria (p=0.0028), and elevated preoperative serum creatinine (p=0.0088) in the MS group, and peritoneal dissemination (p=0.0005) in the PS group. A comparison of stent patency between the groups according to obstruction factors showed no significant differences for lower ureteral obstruction (p=0.5140), direct tumor compression (p=0.8215), or pyuria (p=0.8401). However, among patients with peritoneal dissemination, the stent patency period was significantly longer in the MS group (p=0.0001). Conclusions: Metallic ureteral stenting, which has higher patency rates than PS, is a safe and effective treatment option for MUO, particularly in the patients with peritoneal dissemination. Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction In urological practice, ureteral stent placement is often performed to relieve postrenal acute kidney injury (AKI) caused by malignant ureteral obstruction (MUO), in which ureters are extrinsically compressed by tumors originating from organs outside the urogenital tract. However, when severe ureteral stenosis results from tumor compression or when the ureteral orifice cannot be identified due to bladder invasion, ureteral stent placement becomes technically difficult, and percutaneous nephrostomy is selected instead. The main reasons ureteral stent placement is generally preferred as the first-line intervention are its ease of management and the ability to maintain body image. Ureteral stents are managed by transurethral replacement every 3–6 months, whereas nephrostomy catheters require monthly exchanges, making their management more complex. Furthermore, since the catheter remains exposed outside the body, nephrostomy significantly impairs body image. Although nephrostomy provides reliable urinary drainage and is superior in ensuring the decompression of urinary tract obstruction, it generally reduces patients’ quality of life (QOL). Therefore, many urologists prefer ureteral stenting as the initial treatment option whenever feasible. On the other hand, conventional polymeric ureteral stents (PS) have the unresolved issue of stent failure caused by tumor compression. Consequently, there has been a growing need for new treatment options that ensure long-term urinary drainage while avoiding percutaneous nephrostomy. As one solution, the metallic ureteral stent (MS) (Cook Resonance ® ; Cook Medical, Bloomington, IN, USA) was covered by the Japanese national health insurance system from December 2014, making it available for clinical use. MS is composed of a cobalt–nickel–chromium–molybdenum alloy and exhibits greater resistance to external compression than PS [1]. Therefore, MS is expected to reduce the risk of stent failure and allow the avoidance of nephrostomy, and its safety and efficacy have already been reported [2]. In addition, since the maximum indwelling period of MS is 12 months, its exchange frequency is lower than that of PS, resulting in better cost-effectiveness and a reduced financial burden for patients [3,4]. Patients with MUO often face not only the challenge of preventing stent failure, but also the difficult decision of whether to continue anticancer therapy or transition to palliative care. Since the median survival time after the diagnosis of MUO is generally less than one year [5–7], maintaining QOL while meeting patients’ preferences and goals is crucial in both cancer management and end-of-life care. Therefore, the present study retrospectively compared clinical outcomes and stent patency rates between MS and PS cases at our department to clarify the appropriate selection of ureteral stents for MUO and identify the optimal indications according to patient backgrounds and disease characteristics. Methods Patient characteristics This study included 148 patients (240 ureters) with MUO who underwent ureteral stent placement at our department between December 2014 and April 2022. The cohort comprised 67 patients (112 ureters) who received MS (MS group) and 81 patients (128 ureters) who received PS (PS group). Among those who received MS, 45 patients (80 ureters) had previously undergone PS pre-stenting. We analyzed the overall survival and primary underlying malignancies of patients with MUO and compared operative times, stent patency rates, factors associated with obstruction, and stent patency according to obstruction factors between the two groups. Surgical Technique Stent placement and exchange were performed under general or spinal anesthesia, with the patient in the lithotomy position, using fluoroscopic guidance and transurethral cystoscopy. All stents had a diameter of 6 Fr and a length of 20–26 cm. All ureteral stents were inserted retrogradely; no cases required antegrade placement. Retrograde pyelography was performed under fluoroscopy, and PS was then placed retrogradely using a standard technique with a guidewire, while MS was placed using a retrograde technique with an outer sheath, inner sheath, and guidewire. After removing the guidewire and inner sheath, the inner sheath was reinserted as a pusher into the outer sheath, and the proximal end of the stent was confirmed fluoroscopically to be positioned in the renal pelvis. The outer sheath was then withdrawn, and the distal end of the stent was confirmed to be positioned in the bladder under both cystoscopic and fluoroscopic observations. Follow-up Postoperative evaluations were performed using serum creatinine (SCr) measurements, plain abdominal radiography, computed tomography (CT), and ultrasonography. The timing of these assessments was selected by the attending physician at the outpatient clinic. Stent failure was defined as the development of postrenal AKI regardless of the presence or absence of hydronephrosis, or as any event requiring stent replacement or conversion to nephrostomy due to urinary tract infection (UTI) or other severe complications. Statistical analysis Overall survival rate, stent patency rates, and stent patency period according to obstruction factors were analyzed using the Kaplan–Meier method and evaluated with the Log-rank test. Sex and predictors of stent obstruction were compared between groups using Pearson’s chi-square test, while age and operative times were compared using the Wilcoxon test. A p-value <0.05 was considered to be significant. All statistical analyses were performed using JMP Student Edition version 18.2.1 (SAS Institute Inc.). Results Patient characteristics The baseline characteristics of patients in the MS and PS groups are summarized in Table 1. The underlying causes of MUO were diverse, with gynecologic and gastrointestinal malignancies being the most common. The most frequent primary cancers were cervical, gastric, colorectal, breast, and ovarian cancers, in that order. The mean operative time was significantly longer in the MS group than in the PS group for both bilateral (p=0.0004) and unilateral (p=0.0094) stent placements. Regarding complications, UTI were more frequent in the MS group, and in three of these cases, the stents were subsequently replaced with PS. One case of stent dislodgement occurred in the MS group. No cases of gross hematuria or retroperitoneal urinary leakage were observed in either group. Bladder irritation symptoms were infrequent and comparable between the two groups. Overall survival of MUO The one-year overall survival rate for patients with MUO was 27.2%, and the median survival time was 209 days (Fig. 1). Patency rate of ureteral stents in each group The one-year patency rates of ureteral stents were 62.0% in the MS group and 48.5% in the PS group (Fig. 2), showing a significantly higher rate in the former (p=0.0144). Analysis of factors associated with ureteral stent obstruction The results of the analysis of factors associated with ureteral stent obstruction are summarized in Table 2. In the MS group (Table 2a), peritoneal dissemination correlated with stent patency (p=0.0497). Conversely, lower ureteral obstruction (p=0.0401), direct tumor compression (p=0.0172), preoperative pyuria (p=0.0028), and elevated preoperative SCr (p=0.0088) correlated with stent obstruction. In the PS group (Table 2b), direct tumor compression (p=0.0299) and lymph node metastasis (p=0.0301) correlated with stent patency, whereas peritoneal dissemination correlated with stent obstruction (p=0.0005). When stent patency periods were compared between groups according to these obstruction-related factors using the Kaplan–Meier method, a significantly higher patency rate was observed in the MS group only in patients with peritoneal dissemination (p=0.0001; Fig. 3c). No significant differences were found between groups for other factors (Fig. 3a, b, d). Discussion Ureteral stent placement is a common clinical procedure performed to preserve renal function in cases of postrenal AKI caused by ureteral obstruction due to various benign or malignant diseases. In patients with MUO, progressive compression or obstruction of the ureter often occurs as the underlying malignancy advances, and previous studies indicated that 35–45% of patients experience stent failure after PS placement [8]. Consequently, PS frequently leads to obstruction, often necessitating conversion to percutaneous nephrostomy. Extensive efforts have been made to improve the patency of ureteral stents in MUO patients through modifications in stent design and materials. The MS (Cook Resonance ® ) used in the present study has a highly rigid structure without an inner lumen; it consists of a tightly coiled metal design that allows urine drainage through intercoil gaps. This unique structure differs from that of PS and provides high resistance to external compression, which is considered to contribute to superior stent patency. Complications associated with MS placement include gross hematuria, bladder irritation, UTI, dysuria, pain, encrustation, and subcapsular renal hematoma. Previous studies reported that the frequency of these complications did not markedly differ from that of PS [9,10]. In our institution, as shown in Table 1, no MS-specific complications were observed. Since the insertion technique for MS differs from that for PS, the operative time is generally longer [11]. In the present study, the operative time for MS placement was significantly longer than that for PS. However, no increase in adverse events related to a longer operative time was observed, suggesting that MS may be used as safely as PS. In the present study, the one-year stent patency rate was significantly higher in the MS group (62.0%) than in the PS group (48.5%). Goldsmith et al. reported a one-year patency rate of 65% for MS in patients with MUO [6], which is largely consistent with the present results. Furthermore, Chow et al. reported that MS provides approximately four months longer patency compared to PS [12]. Collectively, these findings suggest that MS offers superior stent patency to PS in the management of MUO. In the analysis of factors associated with stent obstruction, lower ureteral obstruction, direct tumor compression, preoperative pyuria, and elevated preoperative SCr were identified as significant risk factors in the MS group. Previous studies reported several predictors of MS obstruction, including UTI, elevated preoperative SCr, the presence of lower gastrointestinal cancer, ureteral obstruction at the abdominal level, prior radiation therapy, lymph node metastasis, and bilateral ureteral obstruction [5,13,14]. The present results are consistent with these findings. Regarding the relationship between preoperative SCr and MS patency, some studies showed that replacing PS with MS after the normalization of SCr resulted in better patency outcomes [15], and others reported that when preoperative SCr was below 2.0 mg/dL, a longer stent patency period may be expected [12]. Taken together, these findings and the present results indicate that elevated preoperative SCr is associated with a higher risk of MS obstruction. Furthermore, Brown et al. found that patients with UTI had a significantly higher rate of MS obstruction and that the presence of preoperative pyuria increased the risk of obstruction [16]. This may be explained by the structural characteristics of MS, which lacks an inner lumen and, thus, provides slower urinary drainage [17,18]. Accordingly, MS placement needs to be avoided in patients with postrenal AKI who have elevated preoperative SCr or preoperative pyuria. Peritoneal dissemination was associated with stent patency in the MS group and with obstruction in the PS group. Notably, comparisons of the duration of stent patency between the two groups showed that the patency period was significantly longer in patients with peritoneal dissemination in the MS group. These results suggest that MS is more suitable than PS for managing ureteral obstruction caused by peritoneal dissemination. Peritoneal dissemination often leads to continuous ureteral narrowing due to strong extrinsic compression, and previous studies reported that PS, which has lower mechanical strength, was prone to obstruction under these conditions [19]. The present results are consistent with and support these findings. Based on these findings, we developed a flowchart for selecting ureteral stents in patients with MUO at our institution (Fig. 4). As an initial assessment, PS needs to be selected as the first-line option for patients presenting with UTI or postrenal AKI accompanied by elevated SCr, for whom prompt urinary drainage is required. In cases showing the attenuation of UTI or normalization of SCr, the conversion to MS needs to be considered. PS also needs to be selected for patients with severe ureteral stenosis preventing the insertion of a ureteral access sheath, the presence of intraluminal ureteral lesions, or a history of metal allergy. In addition, when a common iliac artery aneurysm is present, PS needs to be selected because MS placement has been reported to cause ureteroarterial fistula formation [20]. Conversely, in patients without these contraindications and with ureteral obstruction due to peritoneal dissemination, MS needs to be considered as the first-line option. To the best of our knowledge, previous comparisons of the clinical outcomes of MS and PS did not include as many cases as the present study, underscoring its clinical relevance. The selection of the appropriate type of ureteral stent based on individual disease characteristics and patient backgrounds is expected to contribute to longer stent patency and improved QOL. Since MUO often causes AKI and UTI that may disrupt cancer treatment, and because its median survival time is less than one year, a rapid intervention and appropriate device selection are critically important in managing this highly urgent condition. Conclusions This study demonstrated that MS is safely used in patients with MUO and had a higher patency rate than PS, particularly in the patients with peritoneal dissemination. A comprehensive understanding of patient backgrounds, disease characteristics, and the specific features of each type of ureteral stent is essential. Continuous efforts are needed to improve QOL in patients with MUO through appropriate device selection. Abbreviations MS: Metallic ureteral stent, PS: Polymeric ureteral stent, MUO: Malignant ureteral obstruction, AKI: acute kidney injury, QOL: Quality of life, OS: Overall survival, UTI: Urinary tract infection, SCr: serum creatinine Declarations Ethical approval and consent to participate The present study was reviewed and approved by the Institutional Review Board of St. Marianna University School of Medicine (Approval No. 5724). The requirement for written informed consent was waived due to the retrospective study design. All procedures were conducted in accordance with the Declaration of Helsinki. Consent for publication Not applicable. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding None. There was no funding to support this study or publication. Acknowledgments The authors would like to express their sincere gratitude to Ms. Satoe Aratake and Ms. Miki Yoshiike for their valuable advice on statistical analyses and manuscript preparation. Authors` contributions TN developed the study design, performed the statistical analysis, and was responsible for the clinical management of patients. TN also drafted the manuscript and critically revised it for important intellectual content. RN contributed to the development of the study design and provided guidance during the study. YM, RY, HT, DS, NY, and KA were involved in the clinical management of patients. EK supervised the study. References Pedro RN, Hendlin K, Kriedberg C, Monga M: Wire-based ureteral stents: impact on tensile strength and compression . Urology 2007, 70 (6):1057-1059. Liatsikos E, Kallidonis P, Kyriazis I, Constantinidis C, Hendlin K, Stolzenburg JU, Karnabatidis D, Siablis D: Ureteral obstruction: is the full metallic double-pigtail stent the way to go? Eur Urol 2010, 57 (3):480-486. López-Huertas HL, Polcari AJ, Acosta-Miranda A, Turk TM: Metallic ureteral stents: a cost-effective method of managing benign upper tract obstruction . J Endourol 2010, 24 (3):483-485. Polcari AJ, Hugen CM, López-Huertas HL, Turk TM: Cost analysis and clinical applicability of the Resonance metallic ureteral stent . Expert Rev Pharmacoecon Outcomes Res 2010, 10 (1):11-15. Wang HJ, Lee TY, Luo HL, Chen CH, Shen YC, Chuang YC, Chiang PH: Application of resonance metallic stents for ureteral obstruction . BJU Int 2011, 108 (3):428-432. Goldsmith ZG, Wang AJ, Bañez LL, Lipkin ME, Ferrandino MN, Preminger GM, Inman BA: Outcomes of metallic stents for malignant ureteral obstruction . J Urol 2012, 188 (3):851-855. Wong LM, Cleeve LK, Milner AD, Pitman AG: Malignant ureteral obstruction: outcomes after intervention. Have things changed? J Urol 2007, 178 (1):178-183; discussion 183. Ganatra AM, Loughlin KR: The management of malignant ureteral obstruction treated with ureteral stents . J Urol 2005, 174 (6):2125-2128. Asakawa J, Iguchi T, Tamada S, Ninomiya N, Kato M, Yamasaki T, Nakatani T: Outcomes of indwelling metallic stents for malignant extrinsic ureteral obstruction . Int J Urol 2018, 25 (3):258-262. Kadlec AO, Ellimoottil CS, Greco KA, Turk TM: Five-year experience with metallic stents for chronic ureteral obstruction . J Urol 2013, 190 (3):937-941. Chen Y, Liu CY, Zhang ZH, Xu PC, Chen DG, Fan XH, Ma JC, Xu YP: Malignant ureteral obstruction: experience and comparative analysis of metallic versus ordinary polymer ureteral stents . World J Surg Oncol 2019, 17 (1):74. Chow PM, Chiang IN, Chen CY, Huang KH, Hsu JS, Wang SM, Lee YJ, Yu HJ, Pu YS, Huang CY: Malignant Ureteral Obstruction: Functional Duration of Metallic versus Polymeric Ureteral Stents . PLoS One 2015, 10 (8):e0135566. Li CC, Li JR, Huang LH, Hung SW, Yang CK, Wang SS, Chen CS, Ou YC, Ho HC, Su CK et al : Metallic stent in the treatment of ureteral obstruction: experience of single institute . J Chin Med Assoc 2011, 74 (10):460-463. Chow PM, Hsu JS, Wang SM, Yu HJ, Pu YS, Liu KL: Metallic ureteral stents in malignant ureteral obstruction: short-term results and radiological features predicting stent failure in patients with non-urological malignancies . World J Urol 2014, 32 (3):729-736. Kobayashi Y AH, and Honda M: Patency period of a metallic ureteral stent and its determinants in patients with malignant ureteral obstruction: a prospective review . Afr J Urol 2021, 27 (1):126. Brown JA, Powell CL, Carlson KR: Metallic full-length ureteral stents: does urinary tract infection cause obstruction? ScientificWorldJournal 2010, 10 :1566-1573. Christman MS, L'esperance JO, Choe CH, Stroup SP, Auge BK: Analysis of ureteral stent compression force and its role in malignant obstruction . J Urol 2009, 181 (1):392-396. Blaschko SD, Deane LA, Krebs A, Abdelshehid CS, Khan F, Borin J, Nguyen A, McDougall EM, Clayman RV: In-vivo evaluation of flow characteristics of novel metal ureteral stent . J Endourol 2007, 21 (7):780-783. Park DS, Park JH, Lee YT: Percutaneous nephrostomy versus indwelling ureteral stents in patients with bilateral nongenitourinary malignant extrinsic obstruction . J Endourol 2002, 16 (3):153-154. Miyauchi Y, Osaki Y, Naito H, Tsunemori H, Itoh M, Kanenishi K, Norikane T, Sanomura T, Nishiyama Y, Sugimoto M: Ureteroiliac artery fistula caused by full-length metallic ureteral stenting in a malignant ureteral obstruction: a case report . J Med Case Rep 2020, 14 (1):195. Tables Table 1 Patient characteristics Characteristics Metallic stent group Polymeric stent group p-value Patients, n 67 81 Male / Female, n 17 / 50 24 / 57 0.5647 Age (years), mean ± SD 65.6±11.9 62.1±13.2 0.0835 Bilateral / Unilateral, n 45 / 22 47 / 34 Operative time (min), mean ± SD Bilateral 45.3±15.4 34.8±16.8 0.0004 Unilateral 30.9±12.5 22.5±10.0 0.0094 Complications, n (%) Urinary tract infection 12 (18) 5 (6) Bladder irritability 5 (7) 2 (2) Migration 1 (1) 0 (0) Causes of MUO, n (%) Uterine cancer 18 (27) 21 (26) Gastric cancer 13 (19) 17 (21) Colorectal cancer 10 (15) 11 (14) Breast cancer 10 (15) 8 (10) Ovarian cancer 7 (10) 6 (7) Malignant lymphoma 4 (6) 6 (7) Occult cancer 1 (2) 3 (4) Others 4 (6) 9 (11) Ureters, n 112 128 Left / Right, n 54 / 58 59 / 69 P-values less than 0.05 are shown in bold. Table 2 Analysis of factors associated with stent patency and obstruction in ureteral units of patients with malignant ureteral obstruction a) Metallic Stent Group n (％) Patency Obstruction p-value Bilateral 61 (79.2) 29 (82.9) 0.6534 Area of obstruction Upper 27 (35.1) 7 (20.0) 0.1080 Middle 21 (27.3) 8 (22.9) 0.6210 Lower 26 (33.8) 19 ( 54.3 ) 0.0401 Pathology of obstruction Direct tumor compression 18 (23.4) 16 ( 45.7 ) 0.0172 Lymph node 15 (19.5) 6 (17.1) 0.7689 Peritoneal dissemination 44 ( 57.1 ) 13 (37.1) 0.0497 Preoperative pyuria 11 (16.2) 13 ( 44.8 ) 0.0028 Radiotherapy (+) 20 (26.0) 15 (42.9) 0.0740 Median basal Cr > 0.72 mg/dl 35 (46.1) 22 (62.9) 0.0998 Median preoperative Cr > 1.4 mg/dl 34 (44.7) 25 ( 71.4 ) 0.0088 b) Polymeric stent group n (％) Patency Obstruction p-value Bilateral 58 (69.9) 34 (75.6) 0.4953 Area of obstruction Upper 12 (14.5) 3 (6.7) 0.1907 Middle 19 (22.9) 14 (31.1) 0.3101 Lower 52 (62.7) 28 (62.2) 0.9616 Pathology of obstruction Direct tumor compression 30 ( 36.1 ) 8 (17.8) 0.0299 Lymph node 15 ( 18.1 ) 2 (4.4) 0.0301 Peritoneal dissemination 38 (45.8) 35 ( 77.9 ) 0.0005 Preoperative pyuria 35 (55.6) 18 (47.4) 0.4248 Radiotherapy (+) 24 (28.9) 20 (44.4) 0.0774 Median basal Cr > 0.72 mg/dl 39 (48.2) 19 (45.2) 0.7592 Median preoperative Cr > 2.1 mg/dl 45 (54.9) 24 (53.3) 0.8672 P-values less than 0.05 and variables with significantly higher proportions between the patent and obstructed groups are shown in bold. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 Jan, 2026 Read the published version in BMC Urology → Version 1 posted Editorial decision: Revision requested 02 Jan, 2026 Reviews received at journal 28 Dec, 2025 Reviews received at journal 28 Dec, 2025 Reviewers agreed at journal 21 Dec, 2025 Reviewers agreed at journal 19 Dec, 2025 Reviews received at journal 19 Dec, 2025 Reviewers agreed at journal 19 Dec, 2025 Reviewers invited by journal 19 Dec, 2025 Editor invited by journal 02 Dec, 2025 Editor assigned by journal 29 Nov, 2025 Submission checks completed at journal 29 Nov, 2025 First submitted to journal 27 Nov, 2025 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. 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Medicine","correspondingAuthor":false,"prefix":"","firstName":"Daisuke","middleName":"","lastName":"Shirai","suffix":""},{"id":563694666,"identity":"f80b8d94-d341-409c-a2c5-0597ee8407b9","order_by":6,"name":"Naoto Yoza","email":"","orcid":"","institution":"St Marianna University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Naoto","middleName":"","lastName":"Yoza","suffix":""},{"id":563694667,"identity":"c593fad8-cc42-4048-9b27-d567e7fe145f","order_by":7,"name":"Koichiro Aida","email":"","orcid":"","institution":"St Marianna University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Koichiro","middleName":"","lastName":"Aida","suffix":""},{"id":563694669,"identity":"4d82384d-c92d-4312-be66-3c57fa59f21c","order_by":8,"name":"Eiji Kikuchi","email":"","orcid":"","institution":"St Marianna University School of Medicine","correspondingAuthor":false,"prefix":"","firstName":"Eiji","middleName":"","lastName":"Kikuchi","suffix":""}],"badges":[],"createdAt":"2025-11-27 05:53:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8218264/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8218264/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12894-026-02062-z","type":"published","date":"2026-01-30T15:58:15+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":99189769,"identity":"920c4f23-505e-4303-a37d-a3dcd0dd145c","added_by":"auto","created_at":"2025-12-30 00:47:41","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":776605,"visible":true,"origin":"","legend":"\u003cp\u003eOverall survival of patients with malignant ureteral obstruction\u003c/p\u003e\n\u003cp\u003eA Kaplan–Meier curve showing overall survival for all patients with MUO during the observation period\u003c/p\u003e","description":"","filename":"Figure.1.png","url":"https://assets-eu.researchsquare.com/files/rs-8218264/v1/da09e9d7d89c0ef308b5ea47.png"},{"id":99316474,"identity":"5e1d63d8-fa4d-43c0-9181-fa4adf297a7a","added_by":"auto","created_at":"2025-12-31 16:28:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":941477,"visible":true,"origin":"","legend":"\u003cp\u003eUreteral stent patency rates in metallic stent and polymeric stent groups\u003c/p\u003e\n\u003cp\u003eKaplan–Meier curves showing ureteral stent patency during the observation period for the MS group (solid line) and PS group (dotted line)\u003c/p\u003e","description":"","filename":"Figure.2.png","url":"https://assets-eu.researchsquare.com/files/rs-8218264/v1/f145f60964db725281397050.png"},{"id":99189766,"identity":"d3e309f3-02e7-4c90-b351-51deebe5ae0c","added_by":"auto","created_at":"2025-12-30 00:47:41","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3758839,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan–Meier curves of ureteral stent patency according to obstruction-related factors in both groups\u003c/p\u003e\n\u003cp\u003eFig. 3a-d. Kaplan–Meier curves showing ureteral stent patency during the observation period for the MS group (solid line) and PS group (dotted line) according to obstruction-related factors: (a) lower ureteral obstruction, (b) direct tumor compression, (c) peritoneal dissemination, and (d) preoperative pyuria. A significant difference was observed for (c), but not for (a), (b), or (d)\u003c/p\u003e","description":"","filename":"Figure.3.png","url":"https://assets-eu.researchsquare.com/files/rs-8218264/v1/27264f753307dc91c8fbe028.png"},{"id":99189768,"identity":"37cd4dd2-e7ca-45a5-9ea4-a86f723c4a23","added_by":"auto","created_at":"2025-12-30 00:47:41","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1863642,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart for ureteral stent selection in patients with malignant ureteral obstruction\u003c/p\u003e","description":"","filename":"Figure.4.png","url":"https://assets-eu.researchsquare.com/files/rs-8218264/v1/bf9c20694e8b58be864915c5.png"},{"id":101691140,"identity":"00b0b900-8e6a-4149-b399-26ce49ddd99a","added_by":"auto","created_at":"2026-02-02 16:12:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9485784,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8218264/v1/887b9982-4500-4ba9-9357-8ff765086c10.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparison of clinical outcomes between metallic and polymeric ureteral stents in malignant ureteral obstruction: A retrospective comparative study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn urological practice, ureteral stent placement is often performed to relieve postrenal acute kidney injury (AKI) caused by malignant ureteral obstruction (MUO), in which ureters are extrinsically compressed by tumors originating from organs outside the urogenital tract. However, when severe ureteral stenosis results from tumor compression or when the ureteral orifice cannot be identified due to bladder invasion, ureteral stent placement becomes technically difficult, and percutaneous nephrostomy is selected instead.\u003c/p\u003e\n\u003cp\u003eThe main reasons ureteral stent placement is generally preferred as the first-line intervention are its ease of management and the ability to maintain body image. Ureteral stents are managed by transurethral replacement every 3–6 months, whereas nephrostomy catheters require monthly exchanges, making their management more complex. Furthermore, since the catheter remains exposed outside the body, nephrostomy significantly impairs body image. Although nephrostomy provides reliable urinary drainage and is superior in ensuring the decompression of urinary tract obstruction, it generally reduces patients’ quality of life (QOL). Therefore, many urologists prefer ureteral stenting as the initial treatment option whenever feasible.\u003c/p\u003e\n\u003cp\u003eOn the other hand, conventional polymeric ureteral stents (PS) have the unresolved issue of stent failure caused by tumor compression. Consequently, there has been a growing need for new treatment options that ensure long-term urinary drainage while avoiding percutaneous nephrostomy. As one solution, the metallic ureteral stent (MS) (Cook Resonance\u003csup\u003e®\u003c/sup\u003e; Cook Medical, Bloomington, IN, USA) was covered by the Japanese national health insurance system from December 2014, making it available for clinical use. MS is composed of a cobalt–nickel–chromium–molybdenum alloy and exhibits greater resistance to external compression than PS [1]. Therefore, MS is expected to reduce the risk of stent failure and allow the avoidance of nephrostomy, and its safety and efficacy have already been reported [2]. In addition, since the maximum indwelling period of MS is 12 months, its exchange frequency is lower than that of PS, resulting in better cost-effectiveness and a reduced financial burden for patients [3,4].\u003c/p\u003e\n\u003cp\u003ePatients with MUO often face not only the challenge of preventing stent failure, but also the difficult decision of whether to continue anticancer therapy or transition to palliative care. Since the median survival time after the diagnosis of MUO is generally less than one year [5–7], maintaining QOL while meeting patients’ preferences and goals is crucial in both cancer management and end-of-life care.\u003c/p\u003e\n\u003cp\u003eTherefore, the present study retrospectively compared clinical outcomes and stent patency rates between MS and PS cases at our department to clarify the appropriate selection of ureteral stents for MUO and identify the optimal indications according to patient backgrounds and disease characteristics.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003ePatient characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study included 148 patients (240 ureters) with MUO who underwent ureteral stent placement at our department between December 2014 and April 2022. The cohort comprised 67 patients (112 ureters) who received MS (MS group) and 81 patients (128 ureters) who received PS (PS group). Among those who received MS, 45 patients (80 ureters) had previously undergone PS pre-stenting.\u0026nbsp;We analyzed the overall survival and primary underlying malignancies of patients with MUO and compared operative times, stent patency rates, factors associated with obstruction, and stent patency according to obstruction factors between the two groups.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSurgical Technique\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStent placement and exchange were performed under general or spinal anesthesia, with the patient in the lithotomy position, using fluoroscopic guidance and transurethral cystoscopy. All stents had a diameter of 6 Fr and a length of 20–26 cm. All ureteral stents were inserted retrogradely; no cases required antegrade placement.\u0026nbsp;Retrograde pyelography was performed under fluoroscopy, and PS was then placed retrogradely using a standard technique with a guidewire, while MS was placed using a retrograde technique with an outer sheath, inner sheath, and guidewire. After removing the guidewire and inner sheath, the inner sheath was reinserted as a pusher into the outer sheath, and the proximal end of the stent was confirmed fluoroscopically to be positioned in the renal pelvis. The outer sheath was then withdrawn, and the distal end of the stent was confirmed to be positioned in the bladder under both cystoscopic and fluoroscopic observations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFollow-up\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePostoperative evaluations were performed using serum creatinine (SCr) measurements, plain abdominal radiography, computed tomography (CT), and ultrasonography. The timing of these assessments was selected by the attending physician at the outpatient clinic. Stent failure was defined as the development of\u0026nbsp;postrenal AKI regardless of the presence or absence of hydronephrosis, or as any event requiring stent replacement or conversion to nephrostomy due to urinary tract infection (UTI) or other severe complications.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOverall survival rate, stent patency rates, and stent patency period according to obstruction factors were analyzed using the Kaplan–Meier method and evaluated with the Log-rank test. Sex and predictors of stent obstruction were compared between groups using Pearson’s chi-square test, while age and operative times were compared using the Wilcoxon test. A p-value \u0026lt;0.05 was considered to be significant. All statistical analyses were performed using JMP Student Edition version 18.2.1 (SAS Institute Inc.).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003ePatient characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe baseline characteristics of patients in the MS and PS groups are summarized in Table 1. The underlying causes of MUO were diverse, with gynecologic and gastrointestinal malignancies being the most common. The most frequent primary cancers were cervical, gastric, colorectal, breast, and ovarian cancers, in that order. The mean operative time was significantly longer in the MS group than in the PS group for both bilateral (p=0.0004) and unilateral (p=0.0094) stent placements. Regarding complications, UTI were more frequent in the MS group, and in three of these cases, the stents were subsequently replaced with PS. One case of stent dislodgement occurred in the MS group. No cases of gross hematuria or retroperitoneal urinary leakage were observed in either group. Bladder irritation symptoms were infrequent and comparable between the two groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOverall survival of MUO\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe one-year overall survival rate for patients with MUO was 27.2%, and the median survival time was 209 days (Fig. 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatency rate of ureteral stents in each group\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe one-year patency rates of ureteral stents were 62.0% in the MS group and 48.5% in the PS group (Fig. 2), showing a significantly higher rate in the former (p=0.0144).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAnalysis of factors associated with ureteral stent obstruction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe results of the analysis of factors associated with ureteral stent obstruction are summarized in Table 2. In the MS group (Table 2a), peritoneal dissemination correlated with stent patency (p=0.0497). Conversely, lower ureteral obstruction (p=0.0401), direct tumor compression (p=0.0172), preoperative pyuria (p=0.0028), and elevated preoperative SCr (p=0.0088) correlated with stent obstruction. In the PS group (Table 2b), direct tumor compression (p=0.0299) and lymph node metastasis (p=0.0301) correlated with stent patency, whereas peritoneal dissemination correlated with stent obstruction (p=0.0005). When stent patency periods were compared between groups according to these obstruction-related factors using the Kaplan–Meier method, a significantly higher patency rate was observed in the MS group only in patients with peritoneal dissemination (p=0.0001; Fig. 3c). No significant differences were found between groups for other factors (Fig. 3a, b, d).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eUreteral stent placement is a common clinical procedure performed to preserve renal function in cases of postrenal AKI caused by ureteral obstruction due to various benign or malignant diseases. In patients with MUO, progressive compression or obstruction of the ureter often occurs as the underlying malignancy advances, and previous studies indicated that 35–45% of patients experience stent failure after PS placement [8]. Consequently, PS frequently leads to obstruction, often necessitating conversion to percutaneous nephrostomy.\u003c/p\u003e\n\u003cp\u003eExtensive efforts have been made to improve the patency of ureteral stents in MUO patients through modifications in stent design and materials. The MS (Cook Resonance\u003csup\u003e®\u003c/sup\u003e) used in the present study has a highly rigid structure without an inner lumen; it consists of a tightly coiled metal design that allows urine drainage through intercoil gaps. This unique structure differs from that of PS and provides high resistance to external compression, which is considered to contribute to superior stent patency.\u003c/p\u003e\n\u003cp\u003eComplications associated with MS placement include gross hematuria, bladder irritation, UTI, dysuria, pain, encrustation, and subcapsular renal hematoma. Previous studies reported that the frequency of these complications did not markedly differ from that of PS [9,10]. In our institution, as shown in Table 1, no MS-specific complications were observed. Since the insertion technique for MS differs from that for PS, the operative time is generally longer [11]. In the present study, the operative time for MS placement was significantly longer than that for PS. However, no increase in adverse events related to a longer operative time was observed, suggesting that MS may be used as safely as PS.\u003c/p\u003e\n\u003cp\u003eIn the present study, the one-year stent patency rate was significantly higher in the MS group (62.0%) than in the PS group (48.5%). Goldsmith et al. reported a one-year patency rate of 65% for MS in patients with MUO [6], which is largely consistent with the present results. Furthermore, Chow et al. reported that MS provides approximately four months longer patency compared to PS [12]. Collectively, these findings suggest that MS offers superior stent patency to PS in the management of MUO.\u003c/p\u003e\n\u003cp\u003eIn the analysis of factors associated with stent obstruction, lower ureteral obstruction, direct tumor compression, preoperative pyuria, and elevated preoperative SCr were identified as significant risk factors in the MS group. Previous studies reported several predictors of MS obstruction, including\u0026nbsp;UTI, elevated preoperative SCr, the presence of lower gastrointestinal cancer, ureteral obstruction at the abdominal level, prior radiation therapy, lymph node metastasis, and bilateral ureteral obstruction [5,13,14]. The present results are consistent with these findings. Regarding the relationship between preoperative SCr and MS patency, some studies showed that replacing PS with MS after the normalization of SCr resulted in better patency outcomes [15], and others reported that when preoperative SCr was below 2.0 mg/dL, a longer stent patency period may be expected [12]. Taken together, these findings and the present results indicate that elevated preoperative SCr is associated with a higher risk of MS obstruction. Furthermore, Brown et al. found that patients with UTI had a significantly higher rate of MS obstruction and that the presence of preoperative pyuria increased the risk of obstruction [16]. This may be explained by the structural characteristics of MS, which lacks an inner lumen and, thus, provides slower urinary drainage [17,18]. Accordingly, MS placement needs to be avoided in patients with postrenal AKI who have elevated preoperative SCr or preoperative pyuria.\u0026nbsp;Peritoneal dissemination was associated with stent patency in the MS group and with obstruction in the PS group. Notably, comparisons of the duration of stent patency between the two groups showed that the patency period was significantly longer in patients with peritoneal dissemination in the MS group. These results suggest that MS is more suitable than PS for managing ureteral obstruction caused by peritoneal dissemination.\u0026nbsp;Peritoneal dissemination often leads to continuous ureteral narrowing due to strong extrinsic compression, and previous studies reported that PS, which has lower mechanical strength, was prone to obstruction under these conditions [19]. The present results are consistent with and support these findings.\u003c/p\u003e\n\u003cp\u003eBased on these findings, we developed a flowchart for selecting ureteral stents in patients with MUO at our institution (Fig. 4). As an initial assessment, PS needs to be selected as the first-line option for patients presenting with UTI or postrenal AKI accompanied by elevated SCr, for whom prompt urinary drainage is required. In cases showing the attenuation of UTI or normalization of SCr, the conversion to MS needs to be considered. PS also needs to be selected for patients with severe ureteral stenosis preventing the insertion of a ureteral access sheath, the presence of intraluminal ureteral lesions, or a history of metal allergy. In addition, when a common iliac artery aneurysm is present, PS needs to be selected because MS placement has been reported to cause ureteroarterial fistula formation [20]. Conversely, in patients without these contraindications and with ureteral obstruction due to peritoneal dissemination, MS needs to be considered as the first-line option.\u003c/p\u003e\n\u003cp\u003eTo the best of our knowledge, previous comparisons of the clinical outcomes of MS and PS did not include as many cases as the present study, underscoring its clinical relevance. The selection of the appropriate type of ureteral stent based on individual disease characteristics and patient backgrounds is expected to contribute to longer stent patency and improved QOL. Since MUO often causes AKI and UTI that may disrupt cancer treatment, and because its median survival time is less than one year, a rapid intervention and appropriate device selection are critically important in managing this highly urgent condition.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study demonstrated that MS is safely used in patients with MUO and had a higher patency rate than PS, particularly in the patients with peritoneal dissemination. A comprehensive understanding of patient backgrounds, disease characteristics, and the specific features of each type of ureteral stent is essential. Continuous efforts are needed to improve QOL in patients with MUO through appropriate device selection.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eMS: Metallic ureteral stent, PS: Polymeric ureteral stent, MUO: Malignant ureteral obstruction, AKI: acute kidney injury, QOL: Quality of life, OS: Overall survival, UTI: Urinary tract infection, SCr: serum creatinine\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe present study was reviewed and approved by the Institutional Review Board of St. Marianna University School of Medicine (Approval No. 5724). The requirement for written informed consent was waived due to the retrospective study design. All procedures were conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone. There was no funding to support this study or publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to express their sincere gratitude to Ms. Satoe Aratake and Ms. Miki Yoshiike for their valuable advice on statistical analyses and manuscript preparation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors` contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTN developed the study design, performed the statistical analysis, and was responsible for the clinical management of patients. TN also drafted the manuscript and critically revised it for important intellectual content. RN contributed to the development of the study design and provided guidance during the study. YM, RY, HT, DS, NY, and KA were involved in the clinical management of patients. EK supervised the study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ePedro RN, Hendlin K, Kriedberg C, Monga M: \u003cstrong\u003eWire-based ureteral stents: impact on tensile strength and compression\u003c/strong\u003e. \u003cem\u003eUrology \u003c/em\u003e2007, \u003cstrong\u003e70\u003c/strong\u003e(6):1057-1059.\u003c/li\u003e\n\u003cli\u003eLiatsikos E, Kallidonis P, Kyriazis I, Constantinidis C, Hendlin K, Stolzenburg JU, Karnabatidis D, Siablis D: \u003cstrong\u003eUreteral obstruction: is the full metallic double-pigtail stent the way to go?\u003c/strong\u003e \u003cem\u003eEur Urol \u003c/em\u003e2010, \u003cstrong\u003e57\u003c/strong\u003e(3):480-486.\u003c/li\u003e\n\u003cli\u003eL\u0026oacute;pez-Huertas HL, Polcari AJ, Acosta-Miranda A, Turk TM: \u003cstrong\u003eMetallic ureteral stents: a cost-effective method of managing benign upper tract obstruction\u003c/strong\u003e. \u003cem\u003eJ Endourol \u003c/em\u003e2010, \u003cstrong\u003e24\u003c/strong\u003e(3):483-485.\u003c/li\u003e\n\u003cli\u003ePolcari AJ, Hugen CM, L\u0026oacute;pez-Huertas HL, Turk TM: \u003cstrong\u003eCost analysis and clinical applicability of the Resonance metallic ureteral stent\u003c/strong\u003e. \u003cem\u003eExpert Rev Pharmacoecon Outcomes Res \u003c/em\u003e2010, \u003cstrong\u003e10\u003c/strong\u003e(1):11-15.\u003c/li\u003e\n\u003cli\u003eWang HJ, Lee TY, Luo HL, Chen CH, Shen YC, Chuang YC, Chiang PH: \u003cstrong\u003eApplication of resonance metallic stents for ureteral obstruction\u003c/strong\u003e. \u003cem\u003eBJU Int \u003c/em\u003e2011, \u003cstrong\u003e108\u003c/strong\u003e(3):428-432.\u003c/li\u003e\n\u003cli\u003eGoldsmith ZG, Wang AJ, Ba\u0026ntilde;ez LL, Lipkin ME, Ferrandino MN, Preminger GM, Inman BA: \u003cstrong\u003eOutcomes of metallic stents for malignant ureteral obstruction\u003c/strong\u003e. \u003cem\u003eJ Urol \u003c/em\u003e2012, \u003cstrong\u003e188\u003c/strong\u003e(3):851-855.\u003c/li\u003e\n\u003cli\u003eWong LM, Cleeve LK, Milner AD, Pitman AG: \u003cstrong\u003eMalignant ureteral obstruction: outcomes after intervention. Have things changed?\u003c/strong\u003e \u003cem\u003eJ Urol \u003c/em\u003e2007, \u003cstrong\u003e178\u003c/strong\u003e(1):178-183; discussion 183.\u003c/li\u003e\n\u003cli\u003eGanatra AM, Loughlin KR: \u003cstrong\u003eThe management of malignant ureteral obstruction treated with ureteral stents\u003c/strong\u003e. \u003cem\u003eJ Urol \u003c/em\u003e2005, \u003cstrong\u003e174\u003c/strong\u003e(6):2125-2128.\u003c/li\u003e\n\u003cli\u003eAsakawa J, Iguchi T, Tamada S, Ninomiya N, Kato M, Yamasaki T, Nakatani T: \u003cstrong\u003eOutcomes of indwelling metallic stents for malignant extrinsic ureteral obstruction\u003c/strong\u003e. \u003cem\u003eInt J Urol \u003c/em\u003e2018, \u003cstrong\u003e25\u003c/strong\u003e(3):258-262.\u003c/li\u003e\n\u003cli\u003eKadlec AO, Ellimoottil CS, Greco KA, Turk TM: \u003cstrong\u003eFive-year experience with metallic stents for chronic ureteral obstruction\u003c/strong\u003e. \u003cem\u003eJ Urol \u003c/em\u003e2013, \u003cstrong\u003e190\u003c/strong\u003e(3):937-941.\u003c/li\u003e\n\u003cli\u003eChen Y, Liu CY, Zhang ZH, Xu PC, Chen DG, Fan XH, Ma JC, Xu YP: \u003cstrong\u003eMalignant ureteral obstruction: experience and comparative analysis of metallic versus ordinary polymer ureteral stents\u003c/strong\u003e. \u003cem\u003eWorld J Surg Oncol \u003c/em\u003e2019, \u003cstrong\u003e17\u003c/strong\u003e(1):74.\u003c/li\u003e\n\u003cli\u003eChow PM, Chiang IN, Chen CY, Huang KH, Hsu JS, Wang SM, Lee YJ, Yu HJ, Pu YS, Huang CY: \u003cstrong\u003eMalignant Ureteral Obstruction: Functional Duration of Metallic versus Polymeric Ureteral Stents\u003c/strong\u003e. \u003cem\u003ePLoS One \u003c/em\u003e2015, \u003cstrong\u003e10\u003c/strong\u003e(8):e0135566.\u003c/li\u003e\n\u003cli\u003eLi CC, Li JR, Huang LH, Hung SW, Yang CK, Wang SS, Chen CS, Ou YC, Ho HC, Su CK\u003cem\u003e et al\u003c/em\u003e: \u003cstrong\u003eMetallic stent in the treatment of ureteral obstruction: experience of single institute\u003c/strong\u003e. \u003cem\u003eJ Chin Med Assoc \u003c/em\u003e2011, \u003cstrong\u003e74\u003c/strong\u003e(10):460-463.\u003c/li\u003e\n\u003cli\u003eChow PM, Hsu JS, Wang SM, Yu HJ, Pu YS, Liu KL: \u003cstrong\u003eMetallic ureteral stents in malignant ureteral obstruction: short-term results and radiological features predicting stent failure in patients with non-urological malignancies\u003c/strong\u003e. \u003cem\u003eWorld J Urol \u003c/em\u003e2014, \u003cstrong\u003e32\u003c/strong\u003e(3):729-736.\u003c/li\u003e\n\u003cli\u003eKobayashi Y AH, and Honda M: \u003cstrong\u003ePatency period of a metallic ureteral stent and its determinants in patients with malignant ureteral obstruction: a prospective review\u003c/strong\u003e. \u003cem\u003eAfr J Urol \u003c/em\u003e2021, \u003cstrong\u003e27\u003c/strong\u003e(1):126.\u003c/li\u003e\n\u003cli\u003eBrown JA, Powell CL, Carlson KR: \u003cstrong\u003eMetallic full-length ureteral stents: does urinary tract infection cause obstruction?\u003c/strong\u003e \u003cem\u003eScientificWorldJournal \u003c/em\u003e2010, \u003cstrong\u003e10\u003c/strong\u003e:1566-1573.\u003c/li\u003e\n\u003cli\u003eChristman MS, L'esperance JO, Choe CH, Stroup SP, Auge BK: \u003cstrong\u003eAnalysis of ureteral stent compression force and its role in malignant obstruction\u003c/strong\u003e. \u003cem\u003eJ Urol \u003c/em\u003e2009, \u003cstrong\u003e181\u003c/strong\u003e(1):392-396.\u003c/li\u003e\n\u003cli\u003eBlaschko SD, Deane LA, Krebs A, Abdelshehid CS, Khan F, Borin J, Nguyen A, McDougall EM, Clayman RV: \u003cstrong\u003eIn-vivo evaluation of flow characteristics of novel metal ureteral stent\u003c/strong\u003e. \u003cem\u003eJ Endourol \u003c/em\u003e2007, \u003cstrong\u003e21\u003c/strong\u003e(7):780-783.\u003c/li\u003e\n\u003cli\u003ePark DS, Park JH, Lee YT: \u003cstrong\u003ePercutaneous nephrostomy versus indwelling ureteral stents in patients with bilateral nongenitourinary malignant extrinsic obstruction\u003c/strong\u003e. \u003cem\u003eJ Endourol \u003c/em\u003e2002, \u003cstrong\u003e16\u003c/strong\u003e(3):153-154.\u003c/li\u003e\n\u003cli\u003eMiyauchi Y, Osaki Y, Naito H, Tsunemori H, Itoh M, Kanenishi K, Norikane T, Sanomura T, Nishiyama Y, Sugimoto M: \u003cstrong\u003eUreteroiliac artery fistula caused by full-length metallic ureteral stenting in a malignant ureteral obstruction: a case report\u003c/strong\u003e. \u003cem\u003eJ Med Case Rep \u003c/em\u003e2020, \u003cstrong\u003e14\u003c/strong\u003e(1):195.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e Patient characteristics\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"99%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eCharacteristics\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003eMetallic stent group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003ePolymeric stent group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003ePatients, n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eMale / Female, n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e17 / 50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e24 / 57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.5647\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eAge (years), mean \u0026plusmn; SD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e65.6\u0026plusmn;11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e62.1\u0026plusmn;13.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.0835\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eBilateral / Unilateral, n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e45 / 22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e47 / 34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eOperative time (min), mean \u0026plusmn; SD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eBilateral\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e45.3\u0026plusmn;15.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e34.8\u0026plusmn;16.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0004\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eUnilateral\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e30.9\u0026plusmn;12.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e22.5\u0026plusmn;10.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0094\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eComplications, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 23px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 26px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eUrinary tract infection\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eBladder irritability\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eMigration\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eCauses of MUO, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eUterine cancer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(27)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eGastric cancer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(19)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eColorectal cancer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eBreast cancer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eOvarian cancer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eMalignant lymphoma\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eOccult cancer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eOthers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 12px;\"\u003e\n \u003cp\u003e(6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12px;\"\u003e\n \u003cp\u003e(11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eUreters, n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e112\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e128\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 37px;\"\u003e\n \u003cp\u003eLeft / Right, n\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 25px;\"\u003e\n \u003cp\u003e54 / 58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 25px;\"\u003e\n \u003cp\u003e59 / 69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" style=\"width: 100px;\"\u003e\n \u003cp\u003eP-values less than 0.05 are shown in bold.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u0026nbsp;\u003c/strong\u003eAnalysis of factors associated with stent patency and obstruction in ureteral units of patients with malignant ureteral obstruction\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003ea) \u003cstrong\u003eMetallic Stent Group\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003en (％)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003ePatency\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003eObstruction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eBilateral\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e61 (79.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e29 (82.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.6534\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eArea of obstruction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eUpper\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e27 (35.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e7 (20.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.1080\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eMiddle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e21 (27.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e8 (22.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.6210\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eLower\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e26 (33.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e19 (\u003cstrong\u003e54.3\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0401\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003ePathology of obstruction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eDirect tumor compression\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e18 (23.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e16 (\u003cstrong\u003e45.7\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0172\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eLymph node\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e15 (19.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e6 (17.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.7689\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003ePeritoneal dissemination\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e44 (\u003cstrong\u003e57.1\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e13 (37.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0497\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003ePreoperative pyuria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e11 (16.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e13 (\u003cstrong\u003e44.8\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0028\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eRadiotherapy (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e20 (26.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e15 (42.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.0740\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eMedian basal Cr \u0026gt; 0.72 mg/dl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e35 (46.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e22 (62.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.0998\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eMedian preoperative Cr \u0026gt; 1.4 mg/dl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e34 (44.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e25 (\u003cstrong\u003e71.4\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0088\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eb) \u003cstrong\u003ePolymeric stent group\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003en (％)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003ePatency\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003eObstruction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eBilateral\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e58 (69.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e34 (75.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.4953\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eArea of obstruction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eUpper\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e12 (14.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e3 (6.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.1907\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eMiddle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e19 (22.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e14 (31.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.3101\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eLower\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e52 (62.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e28 (62.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.9616\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003ePathology of obstruction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eDirect tumor compression\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e30 (\u003cstrong\u003e36.1\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e8 (17.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0299\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eLymph node\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e15 (\u003cstrong\u003e18.1\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e2 (4.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0301\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003ePeritoneal dissemination\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e38 (45.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e35 (\u003cstrong\u003e77.9\u003c/strong\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0005\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003ePreoperative pyuria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e35 (55.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e18 (47.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.4248\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eRadiotherapy (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e24 (28.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e20 (44.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.0774\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eMedian basal Cr \u0026gt; 0.72 mg/dl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e39 (48.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e19 (45.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.7592\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 244px;\"\u003e\n \u003cp\u003eMedian preoperative Cr \u0026gt; 2.1 mg/dl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e45 (54.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e24 (53.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 97px;\"\u003e\n \u003cp\u003e0.8672\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" style=\"width: 533px;\"\u003e\n \u003cp\u003eP-values less than 0.05 and variables with significantly higher proportions between the patent and obstructed groups are shown in bold.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"buro","sideBox":"Learn more about [BMC Urology](http://bmcurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/buro/default.aspx","title":"BMC Urology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8218264/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8218264/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Background:\nThe present study compared the clinical outcomes and indications of metallic ureteral stents (MS) and polymeric ureteral stents (PS) in patients with malignant ureteral obstruction (MUO).\nMethods:\nWe analyzed 148 patients (240 ureters) with MUO who underwent ureteral stent placement at our Department of Urology between December 2014 and April 2022. The cohort included 67 patients (112 ureters) who received metallic stents (MS group) and 81 patients (128 ureters) who received polymeric stents (PS group). We evaluated overall survival and the primary underlying malignancies, and compared operative times, ureteral stent patency rates, and factors associated with stent obstruction between the two groups.\nResults:\nThe one-year overall survival rate of patients with MUO was 27.2%, with a median survival time of 209 days. The main primary malignancies were gynecologic and gastrointestinal cancers, most commonly cervical, gastric, colorectal, breast, and ovarian cancers, in that order. The operative time for stent insertion was significantly longer in the MS group than in the PS group for both bilateral (p=0.0004) and unilateral (p=0.0094) placements. The one-year stent patency rate was significantly higher in the MS group (62.0%) than in the PS group (48.5%) (p=0.0144). Factors associated with stent obstruction included lower ureteral obstruction (p=0.0401), direct tumor compression (p=0.0172), pyuria (p=0.0028), and elevated preoperative serum creatinine (p=0.0088) in the MS group, and peritoneal dissemination (p=0.0005) in the PS group. A comparison of stent patency between the groups according to obstruction factors showed no significant differences for lower ureteral obstruction (p=0.5140), direct tumor compression (p=0.8215), or pyuria (p=0.8401). However, among patients with peritoneal dissemination, the stent patency period was significantly longer in the MS group (p=0.0001).\nConclusions: \nMetallic ureteral stenting, which has higher patency rates than PS, is a safe and effective treatment option for MUO, particularly in the patients with peritoneal dissemination.","manuscriptTitle":"Comparison of clinical outcomes between metallic and polymeric ureteral stents in malignant ureteral obstruction: A retrospective comparative study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-30 00:47:36","doi":"10.21203/rs.3.rs-8218264/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-02T08:16:11+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-28T21:27:42+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-28T12:05:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"229078131725836898592397274029755708597","date":"2025-12-21T17:10:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"117816601523054818073143238785102468451","date":"2025-12-19T19:46:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-19T18:54:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"210373316762182062406254778586499853591","date":"2025-12-19T17:54:20+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-19T17:05:38+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-02T09:26:21+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-29T13:24:12+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-29T13:22:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Urology","date":"2025-11-27T05:46:00+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-urology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"buro","sideBox":"Learn more about [BMC Urology](http://bmcurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/buro/default.aspx","title":"BMC Urology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b068ef8d-f80b-4bf3-b0bf-45de41a70fe7","owner":[],"postedDate":"December 30th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-02-02T16:08:41+00:00","versionOfRecord":{"articleIdentity":"rs-8218264","link":"https://doi.org/10.1186/s12894-026-02062-z","journal":{"identity":"bmc-urology","isVorOnly":false,"title":"BMC Urology"},"publishedOn":"2026-01-30 15:58:15","publishedOnDateReadable":"January 30th, 2026"},"versionCreatedAt":"2025-12-30 00:47:36","video":"","vorDoi":"10.1186/s12894-026-02062-z","vorDoiUrl":"https://doi.org/10.1186/s12894-026-02062-z","workflowStages":[]},"version":"v1","identity":"rs-8218264","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8218264","identity":"rs-8218264","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}