Modified Rendezvous Procedures for the Placement of Thermo- expandable Metallic Stents in the Treatment of Ureteral Stenosis in Renal Transplant Patients

Modified Rendezvous Procedures for the Placement of Thermo- expandable Metallic Stents in the Treatment of Ureteral Stenosis in Renal Transplant Patients | 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 Modified Rendezvous Procedures for the Placement of Thermo- expandable Metallic Stents in the Treatment of Ureteral Stenosis in Renal Transplant Patients Xuming Zhang, Zhichao Chi, Bixiao Wang, Boxing Su, Jianxing Li, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7341939/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 Ureteral stenosis is the most common urological condition after renal transplantation that requires extensive technical knowledge and experience in placing thermo-expandable metal stents using a modified rendezvous procedure. The purpose of this study is to analyze the efficacy and safety of this procedure. A total of six female patients underwent a modified rendezvous operation to receive thermo-expandable metal stents between 2022 and 2024. Postoperative follow-up was undertaken for 1 to 24 months. All stents were successfully placed with a mean operative time of 173.0 minutes and an average hospital stay of 8.8 days. Considerable improvements in hydronephrosis were noted among all patients with no statistically significant variation in mean creatinine levels between preoperative and postoperative periods (P = 0.937). Despite a statistical difference in hemoglobin levels between preoperative measurements and those taken on the first postoperative day (P = 0.022), its clinical significance remains unclear. Moreover, we observed no statistically significant difference in preoperative versus postoperative leukocyte counts (P = 0.410). All stents currently remain suitably positioned and functionally stable. In summary, a modified rendezvous procedure in this study demonstrates both safety and efficacy in treating ureteral stenosis after renal transplantation using thermo-expandable metal stents. Health sciences/Diseases Health sciences/Medical research Health sciences/Urology Ureteral Stenosis Kidney Transplantation Self-expandable Metallic Stents Endoscope Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Kidney transplantation has saved millions of patients since 1954. Nonetheless, several postoperative complications have occurred as a result, such as vascular-related conditions, ureteral obstruction, infectious diseases, etc. 1 . Ureteral stenosis is a common urological complication, occurring with an estimated incidence of 3% 2 . The major cause of ureteral stenosis in renal transplant recipients is the interruption of ureteral blood flow, causing intimal fibrosis 3 . The presence of urological complications is linked to a significant drop in patient survival rates, with ureteral stenosis as the sole factor that predicts reduced kidney graft survival among different urological issues 4 . In the present study, we discuss our initial experience with a thermo-expandable metallic ureteral stent in treating ureteral stenosis among 6 female renal transplant patients. Further, we describe our surgical technique, and technical considerations and provide an initial efficacy and safety assessment. Results All patients were successfully stented, with a mean procedure duration of 173.0 min (113 min-348 min) and a mean hospital stay of 8.8 days (6 days-12 days). The preoperative mean value of renal pelvis width was 15.27 mm. Before discharge, all patients underwent intravenous urography or trans-nephrostomy urography, showing varying relief of hydronephrosis. The mean value of creatinine was 172.16 µmol/L preoperatively and 172.67 µmol/L at the time of discharge, which was not statistically significant (P = 0.937). Figure 1 shows the perioperative and follow-up changes in creatinine levels. On the first postoperative day, the mean value of hemoglobin was 106.84 g/L preoperatively and 101.00 g/L, which was statistically different (P = 0.022). Regarding infectious indicators, the mean value of blood leukocytes was 6.55x10 12 /L preoperatively, and the minimum mean value of 5.79x10 12 /L postoperatively, which were not statistically different (P = 0.410). All 6 patients had UTIs preoperatively, and 5 had been cured postoperatively during the follow-up period, with a cure rate of 83%. The follow-up period ranged between 1 month and 24 months, with all stents remaining properly positioned throughout this duration except for 1 case where surgical intervention was required due to stent displacement. After surgery, another patient experienced recurrent UTIs. However, CT did not reveal any evidence of hydronephrosis. Subsequently, anti-infective treatment caused the resolution of pyrexia and significantly decreased creatinine levels. Discussion The decision to undertake open or minimally invasive surgery is a contentious issue among surgeons. This is because different surgical interventions yield varying prognoses. In the case of distal ureteral stenosis, open surgery has greater success rates than minimally invasive methods, both in initial and secondary therapies. Ureteral reimplantation is a common open treatment with a remarkable success rate of up to 82.4% 5 . However, open surgery often causes increased bleeding, prolonged hospital stays, and prolonged recovery periods. Minimally invasive techniques typically encompass nephrostomy, balloon dilatation, stent placement, and endo-ureterotomy of the stenotic segment. Nevertheless, these procedures cause high recurrence rates with patients significantly having lower graft survival than recipients without ureteral stenosis 4 . Regardless of the minimally invasive surgical procedure, scholars have unanimously agreed to routinely place a ureteral stent following surgery. This is because it can effectively prevent obstruction, colic, and renal failure due to postoperative ureteral edema or passage of debris including stones and blood clots, as well as reduce the probability of reoperation due to urological complications 6 . However, ordinary D-J stents still have non-negligible conditions, including encrustation, migration, infection, pain, medical injury, and even increased graft rejection. In response to these complexities, novel metal stents have emerged in this domain. Herein, we present an initial summary of metallic stents that have been used over the past decade for ureteral stenosis after renal transplantation (Table 2). A helically structured thermo-expandable nickel-titanium metallic stent, the Memokath051 stent has been used in patients with ureteral stenosis after renal transplantation. This has been endorsed by the National Institute for Health and Care Excellence for benign and malignant ureteral strictures because of its complete removability, low pain rate, capacity to prevent endothelial ingrowth, corrosion resistance, and MRI compatibility 7 . Besides, this metallic stent has good long-term efficacy, with arguably a maximum follow-up time of 114 months 8 . Herein, we provide relevant literature citations showing their outcomes (Table 3); however, recent research remains limited. Regarding the efficacy of our procedure, hydronephrosis in patients was significantly alleviated upon their discharge from the hospital, promptly relieving pressure on the kidneys. However, no significant change was observed in creatinine levels between preoperative and postoperative periods. This may be attributed to the relatively short follow-up period, which did not allow for significant recovery of renal function. Similarly, Arkadiusz Miernik et al. used this stent to treat ureteral anastomotic stenosis in 6 patients and observed no statistically significant difference in renal function before and three months after surgery 9 . Nonetheless, this stent effectively mitigates the deterioration of renal function among patients. REUBEN A. JOHNSON also showed that the longer the duration of obstruction, the more difficult recovery of the renal function 10 . A review of the data and all patients revealed a fluid present for at least 4–36 months before admission. Therefore, although the obstruction was released, the recovery of the long-term damage to renal function was difficult during the follow-up time. Regarding safety assessment, we revealed a statistically significant difference in hemoglobin levels before and after surgery. Nonetheless, this is not a clinically significant outcome due to the lack of observed substantial intraoperative bleeding. We further hypothesize that the decrease in hemoglobin levels could be attributed to extensive intraoperative and postoperative rehydration which diluted the blood. All 6 patients had UTIs after admission; however, 5 of them developed remission of UTIs after the procedure. This indicates that the stent may confer reduced susceptibility to infections even among female patients prone to UTIs. This is consistent with a study involving 125 patients, where only 3% required stent removal due to concurrent infections 11 . One patient had a recurrence of Enterobacter cloacae on urine culture at extubation 1 month postoperatively, and at 3 months postoperatively, urine culture revealed E . faecalis instead. P. Kotagiri et al. recently demonstrated that treating asymptomatic bacteriuria (ASB) can mitigate the risk of subsequent progression to UTI 12 . However, Julien Coussement et al. revealed that antibiotic use in ASB patients is not associated with an increased incidence of UTI and may trigger the emergence of drug-resistant strains 13 . Considering these findings and that antibiotic use does not exacerbate UTI risk, antibiotics were used to manage the ASB in this patient. However, the patient developed UTI 3 months later. A significant increase was observed in creatinine (up to 440 umol/L) and fever. The creatinine decreased to 220 umol/L after administering imipenem cilastatin. After stopping the drug, the creatinine levels increased again to 370 umol/L. It is plausible that the UTI may not solely be attributed to the stent considering the triple immunosuppressive therapy of the patient. Conversely, stents can still alleviate hydronephrosis, which we believe helps in treating the infection. In recurrent UTIs with a significant risk for allograft loss 14 , using high-grade antibiotics to control infections instead of removing the stent after UTI development is a suitable strategy. One patient experienced distal migration of the stent on secondary postoperative day (Fig. 2 A). A trans-nephrostomy urography revealed significant contrast accumulation in the renal pelvis and proximal portion of the stent (Fig. 2 B). Additionally, this patient exhibited a significant peak in creatinine levels during the postoperative review. Based on an extensive literature review, the incidence rate of stent migration ranged from 7.7–46.2%, making it the most common complication linked to this particular procedure 15 . Potential explanations for such displacement include inaccurate estimation of stenosis length or inadequate anchoring due to ureteral overdistension 16 . A "double insurance" approach was used to accurately estimate the length of the stenosis. The preoperative visualization of the stenosis location and length was achieved through urography, whereas a flexible ureteroscope was utilized intraoperatively. This technique is more accurate than the conventional technique involving retrograde and/or anterograde urography and marking the extent of stenosis with a metal probe on the lateral aspect of the anterior abdominal wall 17 . Balloon dilators should be avoided to prevent overdistension 18 . Thus, we exclusively used either a fascial dilator or a flexible ureteral sheath during placement. In this patient, we positioned the stent at the renal pelvis and ureteral junction for improved drainage due to the tortuous nature of the ureter. Nonetheless, most of the stents resided in the normal section since the stenotic segment was only approximately 1 cm distal to the ureter. Stent displacement towards the distal direction occurred due to ureter dilation caused by hydronephrosis and peristalsis. As a consequence, stents that significantly exceed the length of strictures should be avoided. Contrast accumulation may not solely be caused by displacement but could also be due to potential blood clots or tissue obstruction within the stent. Surgery was immediately performed for stent repositioning. First, the bladder was accessed via a retrograde ureteroscope, and the metal stent was curled up inside the bladder. A laser was used to excise approximately 5cm of the distal end before placing a guidewire and a thinner D-J inside the metal stent to dredge it, and intraoperatively observe drainage of the clot. Intraoperative drainage successfully resolved blood clot, stopping further stent displacement during postoperative imaging and subsequent follow-up (Fig. 2 C). Subsequently, preventive measures were introduced by reintroducing a transplant kidney-specific D-J stent inside the metal stent for patients experiencing high intraoperative bleeding or poor intraoperative urography results (Fig. 3 ). This approach was adopted in another patient, where successful removal of the D-J stent occurred one month after surgery without any discomfort or lumen blockage. Regarding the surgical approach, we used simultaneous access to the urinary tract via both the anterograde and retrograde approaches, also known as rendezvous procedure (RP). A combined ureteroscope and cystoscope were used to explore the stenotic segment and placement of a guidewire. A stent was placed under full endoscopic surveillance. However, unlike the procedure described by Giorgio Mazzon 19 , our procedure did not require a radiologist to perform an anterograde pyelogram to visualize the ureteral injury or stenosis intraoperatively. We instead used a flexible ureteroscope to explore and identify the location of the stenosis, thus reducing the use of contrast during a single procedure, which is extremely beneficial for patients with renal insufficiency. However, we concur with the essential steps of renal surgery. The guidewire was inserted via the stenotic segment of the ureter under dual-scope vision, ensuring complete traversal from the nephrostomy end to the urethral orifice, thereby establishing a comprehensive "pathway" (Fig. 4 ). The placement of the ureteral stent is performed under direct visualization, ensuring accurate execution of the procedure. The use of RP has been extensively documented in various medical conditions, including ureteral medical injury and malignant stenosis, with reported success rates ranging from 71–89%, validating the safety and efficacy of this procedure 19 . In addition, RP provides a distinct advantage by minimizing surgical trauma, specifically in elderly or frail patients unable to tolerate major surgery. Due to the tortuous ureter of the transplanted kidney, the process of placing guidewires and stents can easily damage the ureteral mucosa. This method, which allows direct visualization of the surgical procedure, can precisely prevent such damage. Furthermore, if intraoperative findings including ureteral stones necessitating intervention are observed, they can be effectively managed under direct endoscopic visualization. Conclusion In conclusion, modified RP, a combined endoscopic approach, allows for intuitive and accurate exploration of ureteral stenosis, whereas the placement of a thermo-expandable metallic ureteral stent emerges as a safe and effective treatment option for patients with post-renal transplantation ureteral stenosis. Considering the limited duration of follow-up in this study, additional large-scale investigations are necessary to ascertain its long-term treatment efficacy. Methods We signed a surgical consent form with the patient prior to surgery and fully informed them that their treatment data may be used in subsequent clinical research. The use of this stent has been approved by the Medical Ethics Committee of Beijing Tsinghua Changgung Hospital. We confirmed that all operations were performed in accordance with relevant guidelines and regulations. Patients A total of 6 female patients were treated at our department between 2022 and 2024 with Memokath051 stent (Pnn Medical A/S, Kvistgaard, Denmark) for ureteral stenosis following renal transplantation. The stenotic lesions were in the distal ureter, such as the ureter and bladder anastomosis. Table 1 shows the baseline characteristics of the patients. Stent Placement Technique The stent deployment technique involved a customized surgical strategy based on the clinical status of the patient. Exploration and guidewire placement: A guidewire was navigated via the pre-existing nephrostomy tract to the renal collecting system. Subsequently, a 14-16Fr percutaneous nephrostomy tract was determined using a fascial dilator. A flexible ureteroscope was placed to investigate and gently remove the original D-J stent. A guidewire was passed through the ureteroscope until it crossed the stenosis and reached the bladder. Thereafter, the guidewire was exteriorized via the urethral orifice using a cystoscope or a ureteroscope. A rigid ureteroscope was used for insertion via the urethra where the guidewire encountered difficulty in passing through the stenosis or occlusion anterogradely. The guidewire was then retrogradely advanced through the ureter and bladder anastomosis under dual-scope visualization, passing through the stenotic segment. The guidewire was subsequently grasped anterogradely, ensuring it was exteriorized lateral to the nephrostomy tract. Dilatation: The ureter was progressively dilated retrogradely using a fascial dilator and a flexible ureteroscope sheath up to 14Fr with the guidewire maintained in a straightened and tensioned position. This was monitored by an anterograde flexible ureteroscope to ensure that the scope sheath completely passed through the stenotic segment. Subsequently, a flexible ureteroscope was used to select an appropriate stent length. Placement of the stent: A correctly sized Memokath051 stent assembly, including the metallic stent and delivery sheath, was retrogradely deployed using an anterograde ureteroscope to ensure that the stent’s fluted end traversed the obstructive segment. Alternatively, the assembly was directly inserted anterogradely. Subsequently, the delivery sheath and the flexible ureteroscope sheath were retracted, and warmed saline (65°C) was infused concurrently until the stent was fully inflated. The stent was kept in the bladder for only about 2 cm and the excess was cut off using a laser. Examination: Patency was assessed by anterograde pyelography through nephrostomy tubes, with smooth drainage into the bladder showing successful stent deployment. Nephrostomy tubes were routinely maintained in all patients postoperatively; After a 1-month interval, their removal was determined by anterograde pyelography or ultrasound. Follow-up and analysis Patients were discharged after meeting the following criteria: (1) Postoperative KUB and urography demonstrate secure stent placement and substantial resolution of hydronephrosis; (2) Declining trends in infectious markers and creatinine levels in laboratory reviews, unlike preoperative values. A 3-month postoperative KUB was carried out to confirm stent retention. We documented surgical duration, hospital stay, pre-and postoperative renal pelvis diameter, pre-and postoperative creatinine levels, pre-operative and first postoperative hemoglobin levels, lowest pre-discharge blood leukocyte count, and the incidence of UTIs. Paired t-tests or Wilcoxon tests were performed to assess the efficacy and safety of stent placement. P < 0.05 was considered statistically significant. Declarations Acknowledgments We would like to acknowledge Ms. Su and Mr. Shouyu Miao for their supporting work in this study. Author contributions Xuming Zhang : Conceptualization (equal); writing-original draft (lead); Formal analysis. Zhichao Chi : Data curation. Bixiao Wang : Writing-original draft (supporting), Boxing Su : Methodology. Jianxing Li : Supervision (equal). Chaoyue Ji : Writing-review. Weiguo Hu : Conceptualization (lead); Supervision (lead). Data availability statement All data supporting this study are included in the article and its supplementary materials. Additional information Competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Funding Declaration NO funding was received for conducting this research. References Kim, P. Y., Shoghi, A. & Fananapazir, G. Renal Transplantation: Immediate and Late Complications. Radiol Clin North Am 61 , 809-820 (2023). https://doi.org/10.1016/j.rcl.2023.04.004 Dinckan, A. et al. Early and late urological complications corrected surgically following renal transplantation. Transpl Int 20 , 702-707 (2007). https://doi.org/10.1111/j.1432-2277.2007.00500.x Hsiao, H. L. et al. Treatment of transplant ureteral stricture with Acucise endoureterotomy: case report and literature review. Kaohsiung J Med Sci 23 , 259-264 (2007). https://doi.org/10.1016/s1607-551x(09)70407-3 Arpali, E. et al. 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Antibiotics versus no therapy in kidney transplant recipients with asymptomatic bacteriuria (BiRT): a pragmatic, multicentre, randomized, controlled trial. Clin Microbiol Infect 27 , 398-405 (2021). https://doi.org/10.1016/j.cmi.2020.09.005 Nascimento, E. H. G., Nascimento, E., Lasmar, M. F. & Fabreti-Oliveira, R. A. Effects of Bacterial Urinary Tract Infection on Clinical Outcome and Survival of Kidney Transplant Patients. Transplant Proc 54 , 1262-1269 (2022). https://doi.org/10.1016/j.transproceed.2022.03.031 Sampogna, G., Grasso, A. & Montanari, E. Expandable metallic ureteral stent: indications and results. Minerva Urol Nefrol 70 , 275-285 (2018). https://doi.org/10.23736/s0393-2249.18.03035-7 Khoo, C. C., Abboudi, H., Cartwright, R., El-Husseiny, T. & Dasgupta, R. Metallic Ureteric Stents in Malignant Ureteric Obstruction: A Systematic Review. Urology 118 , 12-20 (2018). https://doi.org/10.1016/j.urology.2018.01.019 Papatsoris, A. G. & Buchholz, N. A novel thermo-expandable ureteral metal stent for the minimally invasive management of ureteral strictures. J Endourol 24 , 487-491 (2010). https://doi.org/10.1089/end.2009.0138 Agrawal, S., Brown, C. T., Bellamy, E. A. & Kulkarni, R. The thermo-expandable metallic ureteric stent: an 11-year follow-up. BJU Int 103 , 372-376 (2009). https://doi.org/10.1111/j.1464-410X.2008.08018.x Mazzon, G. et al. Long-term Outcomes of Minimally Invasive Rendezvous Procedures to Treat Complex Ureteric Strictures and Injuries. Eur Urol Open Sci 49 , 53-59 (2023). https://doi.org/10.1016/j.euros.2022.12.014 Xu, G. et al. Use of Self-Expanding Metallic Ureteral Stents in the Secondary Treatment of Ureteral Stenosis Following Kidney Transplantation. J Endourol 29 , 1199-1203 (2015). https://doi.org/10.1089/end.2015.0188 Sedigh, O. et al. Self-Expandable Covered Metallic Stent (UVENTA) to Treat a Ureteral Stricture After Renal Transplant: A Case Report. Exp Clin Transplant 18 , 116-119 (2020). https://doi.org/10.6002/ect.2017.0197 Salamanca-Bustos, J. J. et al. Initial Experience in the Use of Novel Auto-expandable Metal Ureteral Stent in the Treatment of Ureter Stenosis in Kidney Transplanted Patients. Transplant Proc 50 , 587-590 (2018). https://doi.org/10.1016/j.transproceed.2017.09.048 Zhong, Q. et al. Initial experiment of self-expanding metal ureteral stent in recurrent ureteral stenosis after kidney transplantation. Am J Transplant 21 , 1983-1984 (2021). https://doi.org/10.1111/ajt.16444 Cao, C. et al. Temporary Covered Metallic Ureteral Stent Placement for Ureteral Strictures following Kidney Transplantation: Experience in 8 Patients. J Vasc Interv Radiol 31 , 1795-1800 (2020). https://doi.org/10.1016/j.jvir.2020.04.004 Boyvat, F. et al. Memokath metallic stent in the treatment of transplant kidney ureter stenosis or occlusion. Cardiovasc Intervent Radiol 28 , 326-330 (2005). https://doi.org/10.1007/s00270-004-0028-2 Bach, C. et al. Endourological management of ureteric strictures after kidney transplantation: Stenting the stent. Arab J Urol 9 , 165-169 (2011). https://doi.org/10.1016/j.aju.2011.08.001 Bach, C. et al. A self-expanding thermolabile nitinol stent as a minimally invasive treatment alternative for ureteral strictures in renal transplant patients. J Endourol 27 , 1543-1545 (2013). https://doi.org/10.1089/end.2013.0180 Treacy, P. J., Rastinehad, A. R., Imbert de la Phalecque, L., Albano, L. & Durand, M. Endoureteral Management of Renal Graft Ureteral Stenosis by the Use of Long-Term Metal Stent: An Appealing Treatment Option. J Endourol Case Rep 2 , 155-158 (2016). https://doi.org/10.1089/cren.2016.0084 Tables Table 1. Basal Patients Characteristics N/Age/Sex Localitation/Length(mm) Stent Size(mm) Cre(μmol/L) RPW(mm) Treatment-pre Complications 1/33/F Distal/10 100 115 20.70 D-J Stent, Nephrostomy, balloon dilation Hypertension UTIs 2/35/F Distal/10 100 173 19.10 D-J Stent, Nephrostomy, balloon dilation UTIs 3/40/F Distal/40 150 243 13.00 D-J Stent, Nephrostomy Hypertension, UTIs, Hyperuricemia 4/57/F Distal/50 150 145 16.20 D-J Stent Hypertension, UTIs, Osteoporosis, GERD 5/61/F Distal/20 100 259 14.60 D-J Stent Hypertension, UTIs, Shingles 6/42/F Distal/50 150 98 8.00 D-J Stent Hypertension, UTIs, Cre= creatinine; Hb= hemoglobin; RPW= renal pelvis width Table 2. Characteristics of Metal Stents Used in Last Decade Study Patients Type of stent Follow-up(months) Characteristics Guibin Xu 20 7 AnDaXing 13-86 Technically success rate (100%), lower urinary-tract symptoms (6/7), ipsilateral flank pain (4/7), urothelial hyperplasia-induced obstruction (1/7) Omid Sedigh 21 1 UVENTA 12 No complications, renal function remained stable and there were no signs of recurrence after removed. J J Salamanca-Bustos 22 5 UVENTA 4-38 Technically success rate (100%), renal graft loss (1/5), UTI (1/5), hydronephrosis correction rate (100%) Qiang Zhong 23 8 Allium 5-17 Success rate (86%), release of obstruction (100%), stent migration (2/8) Chuanwu Cao 24 8 Urexel 2-27 Hematuria (2/8), pain (3/8), stent migration (2/8), urothelial hyperplasia (2/8), recurrence (2/8) Table 3. Characteristics of Memokath051 Used to Treat Transplant Ureteral Stenosis Study Patients Follow-up(months) Characteristics Fatih Boyvat 25 4 18–21 Technically success rate (100%), stent migration (1/4), UTI (1/4) Christian Bach 26 1 27 Successfully replace a previously placed metal self-expanding mesh stent without the previous problems of encrustation and endothelial ingrowth. Christian Bach 27 8 55（mean） Long-term success rate (87%), stent migration (1/8), spontaneous resolution of the stricture (3/8) Patrick-Julien Treacy 28 1 36 One week after surgery, there is a major decrease of serum creatinine and a complete restriction of the pelvic dilation, and no complications during follow-up. Additional Declarations No competing interests reported. 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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-7341939","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":511345730,"identity":"fa3b9992-75f8-4768-9e7b-abd4b349d100","order_by":0,"name":"Xuming Zhang","email":"","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xuming","middleName":"","lastName":"Zhang","suffix":""},{"id":511345731,"identity":"62f8b2e2-0d1c-40ea-8cce-61af334c4951","order_by":1,"name":"Zhichao Chi","email":"","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":false,"prefix":"","firstName":"Zhichao","middleName":"","lastName":"Chi","suffix":""},{"id":511345732,"identity":"2e9962c7-3b0d-4cdd-9eb7-8078c24a10a5","order_by":2,"name":"Bixiao Wang","email":"","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bixiao","middleName":"","lastName":"Wang","suffix":""},{"id":511345733,"identity":"a772d8dd-7c74-414e-9cbb-b8bc04fcb39e","order_by":3,"name":"Boxing Su","email":"","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":false,"prefix":"","firstName":"Boxing","middleName":"","lastName":"Su","suffix":""},{"id":511345734,"identity":"aadb49cd-56a3-41e5-a58c-f6fe29f1ddaf","order_by":4,"name":"Jianxing Li","email":"","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jianxing","middleName":"","lastName":"Li","suffix":""},{"id":511345735,"identity":"2583ac47-9e94-403e-b0eb-07c03ad981b4","order_by":5,"name":"Chaoyue Ji","email":"","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chaoyue","middleName":"","lastName":"Ji","suffix":""},{"id":511345736,"identity":"8618b0e6-0e7c-4ad6-9bc2-4ad7957f4670","order_by":6,"name":"Weiguo Hu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8ElEQVRIiWNgGAWjYBACgwOMDUDqAAM/M/MBgw8GNnbEa5Fsb0sonFGQlkyEFjB1gMHgzBmDzzwfDoFNwK/leHPza56KO4kNNxIMN9sYHGBmYD98dAM+LWZnDrZZ85x5ltg4IyHZOMfgDh8DT1raDbxabiS2GfO2HU5slkg4BtTyjJlBgscMv5b7DyFa2iQS239bGBxmbCCkxf4GY/NjkJYensMMxgzEaLE8k9jGOOfMYeMZ7G0Mhj0GaclshPxicPz44w9vKg7L7j/M/8Hgxx8bO372w8fwagECNglULgHlIMD8gQhFo2AUjIJRMJIBAGg3WFUOKfKLAAAAAElFTkSuQmCC","orcid":"","institution":"Beijing Tsinghua Chang Gung Hospital","correspondingAuthor":true,"prefix":"","firstName":"Weiguo","middleName":"","lastName":"Hu","suffix":""}],"badges":[],"createdAt":"2025-08-11 03:38:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7341939/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7341939/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91189889,"identity":"71e52e85-a849-4db6-a198-6b8f17eb1949","added_by":"auto","created_at":"2025-09-12 14:33:03","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":210450,"visible":true,"origin":"","legend":"\u003cp\u003eCreatinine value (μmol/L) evolution pre- and post-stent.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7341939/v1/28d913dd607008db2456d57a.png"},{"id":91191971,"identity":"ea5ed035-ac80-49e2-9e95-55ea2476f3b1","added_by":"auto","created_at":"2025-09-12 14:41:03","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":580403,"visible":true,"origin":"","legend":"\u003cp\u003e(A) The stent migrated distally, and the caudal end is coiled in the bladder. (B) Contrast agent accumulates in the renal pelvis and proximal part of the stent. (C) KUB after the stent has been adjusted for position and length.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7341939/v1/b74c59ee98c87925a62facd6.png"},{"id":91193997,"identity":"eaa5c98b-eb2b-4789-bbcb-342048d2f9b5","added_by":"auto","created_at":"2025-09-12 14:49:04","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2042900,"visible":true,"origin":"","legend":"\u003cp\u003eA special D-J stent for transplanted kidneys is placed inside the metallic stent.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7341939/v1/97fab38aec7a2dde3446e7f0.png"},{"id":91191972,"identity":"c117921a-e19d-47f2-b379-b3b300fc84a9","added_by":"auto","created_at":"2025-09-12 14:41:04","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2083497,"visible":true,"origin":"","legend":"\u003cp\u003eThe guidewire passed through the entire urinary tract.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7341939/v1/ecfa1567228ed8e042c946a0.png"},{"id":104397263,"identity":"367b21ae-63f0-42e5-8aec-e4d349a77e82","added_by":"auto","created_at":"2026-03-11 11:45:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5989140,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7341939/v1/c1b98abc-3c18-45b9-9195-2ed768300b86.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Modified Rendezvous Procedures for the Placement of Thermo- expandable Metallic Stents in the Treatment of Ureteral Stenosis in Renal Transplant Patients","fulltext":[{"header":"Introduction","content":"\u003cp\u003eKidney transplantation has saved millions of patients since 1954. Nonetheless, several postoperative complications have occurred as a result, such as vascular-related conditions, ureteral obstruction, infectious diseases, etc. \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. Ureteral stenosis is a common urological complication, occurring with an estimated incidence of 3% \u003csup\u003e2\u003c/sup\u003e. The major cause of ureteral stenosis in renal transplant recipients is the interruption of ureteral blood flow, causing intimal fibrosis \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. The presence of urological complications is linked to a significant drop in patient survival rates, with ureteral stenosis as the sole factor that predicts reduced kidney graft survival among different urological issues \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIn the present study, we discuss our initial experience with a thermo-expandable metallic ureteral stent in treating ureteral stenosis among 6 female renal transplant patients. Further, we describe our surgical technique, and technical considerations and provide an initial efficacy and safety assessment.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eAll patients were successfully stented, with a mean procedure duration of 173.0 min (113 min-348 min) and a mean hospital stay of 8.8 days (6 days-12 days). The preoperative mean value of renal pelvis width was 15.27 mm. Before discharge, all patients underwent intravenous urography or trans-nephrostomy urography, showing varying relief of hydronephrosis. The mean value of creatinine was 172.16 \u0026micro;mol/L preoperatively and 172.67 \u0026micro;mol/L at the time of discharge, which was not statistically significant (P\u0026thinsp;=\u0026thinsp;0.937). Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the perioperative and follow-up changes in creatinine levels. On the first postoperative day, the mean value of hemoglobin was 106.84 g/L preoperatively and 101.00 g/L, which was statistically different (P\u0026thinsp;=\u0026thinsp;0.022). Regarding infectious indicators, the mean value of blood leukocytes was 6.55x10\u003csup\u003e12\u003c/sup\u003e/L preoperatively, and the minimum mean value of 5.79x10\u003csup\u003e12\u003c/sup\u003e/L postoperatively, which were not statistically different (P\u0026thinsp;=\u0026thinsp;0.410). All 6 patients had UTIs preoperatively, and 5 had been cured postoperatively during the follow-up period, with a cure rate of 83%.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe follow-up period ranged between 1 month and 24 months, with all stents remaining properly positioned throughout this duration except for 1 case where surgical intervention was required due to stent displacement. After surgery, another patient experienced recurrent UTIs. However, CT did not reveal any evidence of hydronephrosis. Subsequently, anti-infective treatment caused the resolution of pyrexia and significantly decreased creatinine levels.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe decision to undertake open or minimally invasive surgery is a contentious issue among surgeons. This is because different surgical interventions yield varying prognoses. In the case of distal ureteral stenosis, open surgery has greater success rates than minimally invasive methods, both in initial and secondary therapies.\u003c/p\u003e\u003cp\u003eUreteral reimplantation is a common open treatment with a remarkable success rate of up to 82.4% \u003csup\u003e5\u003c/sup\u003e. However, open surgery often causes increased bleeding, prolonged hospital stays, and prolonged recovery periods. Minimally invasive techniques typically encompass nephrostomy, balloon dilatation, stent placement, and endo-ureterotomy of the stenotic segment. Nevertheless, these procedures cause high recurrence rates with patients significantly having lower graft survival than recipients without ureteral stenosis \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Regardless of the minimally invasive surgical procedure, scholars have unanimously agreed to routinely place a ureteral stent following surgery. This is because it can effectively prevent obstruction, colic, and renal failure due to postoperative ureteral edema or passage of debris including stones and blood clots, as well as reduce the probability of reoperation due to urological complications \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. However, ordinary D-J stents still have non-negligible conditions, including encrustation, migration, infection, pain, medical injury, and even increased graft rejection.\u003c/p\u003e\u003cp\u003eIn response to these complexities, novel metal stents have emerged in this domain. Herein, we present an initial summary of metallic stents that have been used over the past decade for ureteral stenosis after renal transplantation (Table\u0026nbsp;2). A helically structured thermo-expandable nickel-titanium metallic stent, the Memokath051 stent has been used in patients with ureteral stenosis after renal transplantation. This has been endorsed by the National Institute for Health and Care Excellence for benign and malignant ureteral strictures because of its complete removability, low pain rate, capacity to prevent endothelial ingrowth, corrosion resistance, and MRI compatibility \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e. Besides, this metallic stent has good long-term efficacy, with arguably a maximum follow-up time of 114 months \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Herein, we provide relevant literature citations showing their outcomes (Table\u0026nbsp;3); however, recent research remains limited.\u003c/p\u003e\u003cp\u003eRegarding the efficacy of our procedure, hydronephrosis in patients was significantly alleviated upon their discharge from the hospital, promptly relieving pressure on the kidneys. However, no significant change was observed in creatinine levels between preoperative and postoperative periods. This may be attributed to the relatively short follow-up period, which did not allow for significant recovery of renal function. Similarly, Arkadiusz Miernik et al. used this stent to treat ureteral anastomotic stenosis in 6 patients and observed no statistically significant difference in renal function before and three months after surgery \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Nonetheless, this stent effectively mitigates the deterioration of renal function among patients. REUBEN A. JOHNSON also showed that the longer the duration of obstruction, the more difficult recovery of the renal function \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. A review of the data and all patients revealed a fluid present for at least 4\u0026ndash;36 months before admission. Therefore, although the obstruction was released, the recovery of the long-term damage to renal function was difficult during the follow-up time. Regarding safety assessment, we revealed a statistically significant difference in hemoglobin levels before and after surgery. Nonetheless, this is not a clinically significant outcome due to the lack of observed substantial intraoperative bleeding. We further hypothesize that the decrease in hemoglobin levels could be attributed to extensive intraoperative and postoperative rehydration which diluted the blood. All 6 patients had UTIs after admission; however, 5 of them developed remission of UTIs after the procedure. This indicates that the stent may confer reduced susceptibility to infections even among female patients prone to UTIs. This is consistent with a study involving 125 patients, where only 3% required stent removal due to concurrent infections \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. One patient had a recurrence of \u003cem\u003eEnterobacter cloacae\u003c/em\u003e on urine culture at extubation 1 month postoperatively, and at 3 months postoperatively, urine culture revealed \u003cem\u003eE\u003c/em\u003e. \u003cem\u003efaecalis\u003c/em\u003e instead. P. Kotagiri et al. recently demonstrated that treating asymptomatic bacteriuria (ASB) can mitigate the risk of subsequent progression to UTI \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. However, Julien Coussement et al. revealed that antibiotic use in ASB patients is not associated with an increased incidence of UTI and may trigger the emergence of drug-resistant strains \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. Considering these findings and that antibiotic use does not exacerbate UTI risk, antibiotics were used to manage the ASB in this patient. However, the patient developed UTI 3 months later. A significant increase was observed in creatinine (up to 440 umol/L) and fever. The creatinine decreased to 220 umol/L after administering imipenem cilastatin. After stopping the drug, the creatinine levels increased again to 370 umol/L. It is plausible that the UTI may not solely be attributed to the stent considering the triple immunosuppressive therapy of the patient. Conversely, stents can still alleviate hydronephrosis, which we believe helps in treating the infection. In recurrent UTIs with a significant risk for allograft loss \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e, using high-grade antibiotics to control infections instead of removing the stent after UTI development is a suitable strategy.\u003c/p\u003e\u003cp\u003eOne patient experienced distal migration of the stent on secondary postoperative day (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). A trans-nephrostomy urography revealed significant contrast accumulation in the renal pelvis and proximal portion of the stent (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB). Additionally, this patient exhibited a significant peak in creatinine levels during the postoperative review. Based on an extensive literature review, the incidence rate of stent migration ranged from 7.7\u0026ndash;46.2%, making it the most common complication linked to this particular procedure \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. Potential explanations for such displacement include inaccurate estimation of stenosis length or inadequate anchoring due to ureteral overdistension \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. A \"double insurance\" approach was used to accurately estimate the length of the stenosis. The preoperative visualization of the stenosis location and length was achieved through urography, whereas a flexible ureteroscope was utilized intraoperatively. This technique is more accurate than the conventional technique involving retrograde and/or anterograde urography and marking the extent of stenosis with a metal probe on the lateral aspect of the anterior abdominal wall \u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Balloon dilators should be avoided to prevent overdistension \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. Thus, we exclusively used either a fascial dilator or a flexible ureteral sheath during placement. In this patient, we positioned the stent at the renal pelvis and ureteral junction for improved drainage due to the tortuous nature of the ureter. Nonetheless, most of the stents resided in the normal section since the stenotic segment was only approximately 1 cm distal to the ureter. Stent displacement towards the distal direction occurred due to ureter dilation caused by hydronephrosis and peristalsis. As a consequence, stents that significantly exceed the length of strictures should be avoided. Contrast accumulation may not solely be caused by displacement but could also be due to potential blood clots or tissue obstruction within the stent. Surgery was immediately performed for stent repositioning. First, the bladder was accessed via a retrograde ureteroscope, and the metal stent was curled up inside the bladder. A laser was used to excise approximately 5cm of the distal end before placing a guidewire and a thinner D-J inside the metal stent to dredge it, and intraoperatively observe drainage of the clot. Intraoperative drainage successfully resolved blood clot, stopping further stent displacement during postoperative imaging and subsequent follow-up (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC). Subsequently, preventive measures were introduced by reintroducing a transplant kidney-specific D-J stent inside the metal stent for patients experiencing high intraoperative bleeding or poor intraoperative urography results (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This approach was adopted in another patient, where successful removal of the D-J stent occurred one month after surgery without any discomfort or lumen blockage.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eRegarding the surgical approach, we used simultaneous access to the urinary tract via both the anterograde and retrograde approaches, also known as rendezvous procedure (RP). A combined ureteroscope and cystoscope were used to explore the stenotic segment and placement of a guidewire. A stent was placed under full endoscopic surveillance. However, unlike the procedure described by Giorgio Mazzon \u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e, our procedure did not require a radiologist to perform an anterograde pyelogram to visualize the ureteral injury or stenosis intraoperatively. We instead used a flexible ureteroscope to explore and identify the location of the stenosis, thus reducing the use of contrast during a single procedure, which is extremely beneficial for patients with renal insufficiency. However, we concur with the essential steps of renal surgery. The guidewire was inserted via the stenotic segment of the ureter under dual-scope vision, ensuring complete traversal from the nephrostomy end to the urethral orifice, thereby establishing a comprehensive \"pathway\" (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The placement of the ureteral stent is performed under direct visualization, ensuring accurate execution of the procedure. The use of RP has been extensively documented in various medical conditions, including ureteral medical injury and malignant stenosis, with reported success rates ranging from 71\u0026ndash;89%, validating the safety and efficacy of this procedure \u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. In addition, RP provides a distinct advantage by minimizing surgical trauma, specifically in elderly or frail patients unable to tolerate major surgery. Due to the tortuous ureter of the transplanted kidney, the process of placing guidewires and stents can easily damage the ureteral mucosa. This method, which allows direct visualization of the surgical procedure, can precisely prevent such damage. Furthermore, if intraoperative findings including ureteral stones necessitating intervention are observed, they can be effectively managed under direct endoscopic visualization.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, modified RP, a combined endoscopic approach, allows for intuitive and accurate exploration of ureteral stenosis, whereas the placement of a thermo-expandable metallic ureteral stent emerges as a safe and effective treatment option for patients with post-renal transplantation ureteral stenosis. Considering the limited duration of follow-up in this study, additional large-scale investigations are necessary to ascertain its long-term treatment efficacy.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eWe signed a surgical consent form with the patient prior to surgery and fully informed them that their treatment data may be used in subsequent clinical research. The use of this stent has been approved by the Medical Ethics Committee of Beijing Tsinghua Changgung Hospital. We confirmed that all operations were performed in accordance with relevant guidelines and regulations.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatients\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 6 female patients were treated at our department between 2022 and 2024 with Memokath051 stent\u0026nbsp;(Pnn Medical A/S, Kvistgaard, Denmark) for ureteral stenosis following renal transplantation. The stenotic lesions were in the distal ureter, such as the ureter and bladder anastomosis. Table 1 shows the baseline characteristics of the patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStent Placement Technique\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe stent deployment technique involved a customized surgical strategy based on the clinical status of the patient.\u003c/p\u003e\n\u003cp\u003eExploration and guidewire placement: A guidewire was navigated via the pre-existing nephrostomy tract to the renal collecting system. Subsequently, a 14-16Fr percutaneous nephrostomy tract was determined using a fascial dilator. A flexible ureteroscope was placed to investigate and gently remove the original D-J stent. A guidewire was passed through the ureteroscope until it crossed the stenosis and reached the bladder. Thereafter, the guidewire was exteriorized via the urethral orifice using a cystoscope or a ureteroscope. A rigid ureteroscope was used for insertion via the urethra where the guidewire encountered difficulty in passing through the stenosis or occlusion anterogradely. The guidewire was then retrogradely advanced through the ureter and bladder anastomosis under dual-scope visualization, passing through the stenotic segment. The guidewire was subsequently grasped anterogradely, ensuring it was exteriorized lateral to the nephrostomy tract.\u003c/p\u003e\n\u003cp\u003eDilatation: The ureter was progressively dilated retrogradely using a fascial dilator and a flexible ureteroscope sheath up to 14Fr with the guidewire maintained in a straightened and tensioned position. This was monitored by an anterograde flexible ureteroscope to ensure that the scope sheath completely passed through the stenotic segment. Subsequently, a flexible ureteroscope was used to select an appropriate stent length.\u003c/p\u003e\n\u003cp\u003ePlacement of the stent: A correctly sized Memokath051 stent assembly, including the metallic stent and delivery sheath, was retrogradely deployed using an anterograde ureteroscope to ensure that the stent\u0026rsquo;s fluted end traversed the obstructive segment. Alternatively, the assembly was directly inserted anterogradely. Subsequently, the delivery sheath and the flexible ureteroscope sheath were retracted, and warmed saline (65\u0026deg;C) was infused concurrently until the stent was fully inflated. The stent was kept in the bladder for only about 2 cm and the excess was cut off using a laser.\u003c/p\u003e\n\u003cp\u003eExamination: Patency was assessed by anterograde pyelography through nephrostomy tubes, with smooth drainage into the bladder showing successful stent deployment.\u003c/p\u003e\n\u003cp\u003eNephrostomy tubes were routinely maintained in all patients postoperatively; After a 1-month interval, their removal was determined by anterograde pyelography or ultrasound.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFollow-up and analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients were discharged after meeting the following criteria: (1) Postoperative KUB and urography demonstrate secure stent placement and substantial resolution of hydronephrosis; (2) Declining trends in infectious markers and creatinine levels in laboratory reviews, unlike preoperative values. A 3-month postoperative KUB was carried out to confirm stent retention. We documented surgical duration, hospital stay, pre-and postoperative renal pelvis diameter, pre-and postoperative creatinine levels, pre-operative and first postoperative hemoglobin levels, lowest pre-discharge blood leukocyte count, and the incidence of UTIs.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePaired t-tests or Wilcoxon tests were performed to assess the efficacy and safety of stent placement. P \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to acknowledge Ms. Su and Mr. Shouyu Miao for their supporting work in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eXuming Zhang\u003c/strong\u003e: Conceptualization (equal); writing-original draft (lead);\u0026nbsp;Formal analysis. \u003cstrong\u003eZhichao Chi\u003c/strong\u003e: Data curation.\u003cstrong\u003e\u0026nbsp;Bixiao Wang\u003c/strong\u003e:\u0026nbsp;Writing-original draft (supporting), \u003cstrong\u003eBoxing Su\u003c/strong\u003e: Methodology. \u003cstrong\u003eJianxing Li\u003c/strong\u003e:\u0026nbsp;Supervision (equal).\u003cstrong\u003e\u0026nbsp;Chaoyue Ji\u003c/strong\u003e: Writing-review.\u003cstrong\u003e\u0026nbsp;Weiguo Hu\u003c/strong\u003e: Conceptualization (lead); Supervision (lead).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data supporting this study are included in the article and its supplementary materials.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNO funding was received for conducting this research.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKim, P. Y., Shoghi, A. \u0026amp; Fananapazir, G. Renal Transplantation: Immediate and Late Complications. \u003cem\u003eRadiol Clin North Am\u003c/em\u003e \u003cstrong\u003e61\u003c/strong\u003e, 809-820 (2023). https://doi.org/10.1016/j.rcl.2023.04.004\u003c/li\u003e\n\u003cli\u003eDinckan, A.\u003cem\u003e et al.\u003c/em\u003e Early and late urological complications corrected surgically following renal transplantation. \u003cem\u003eTranspl Int\u003c/em\u003e \u003cstrong\u003e20\u003c/strong\u003e, 702-707 (2007). https://doi.org/10.1111/j.1432-2277.2007.00500.x\u003c/li\u003e\n\u003cli\u003eHsiao, H. 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Impact of Thermo-Expandable Memokath Ureteral Stent on Renal Function in the Management of Ureteroileal Anastomotic Stricture. \u003cem\u003eUrol Int\u003c/em\u003e \u003cstrong\u003e101\u003c/strong\u003e, 313-319 (2018). https://doi.org/10.1159/000492720\u003c/li\u003e\n\u003cli\u003eJohnson, R. A. RENAL FUNCTION IN EXPERIMENTAL HYDRONEPHROSIS. \u003cem\u003eJ Exp Med\u003c/em\u003e \u003cstrong\u003e28\u003c/strong\u003e, 193-212 (1918). https://doi.org/10.1084/jem.28.2.193\u003c/li\u003e\n\u003cli\u003eBier, S.\u003cem\u003e et al.\u003c/em\u003e The thermoexpandable nitinol stent: a long-term alternative in patients without nephropathy or malignancy. \u003cem\u003eScand J Urol\u003c/em\u003e \u003cstrong\u003e51\u003c/strong\u003e, 388-391 (2017). https://doi.org/10.1080/21681805.2017.1331262\u003c/li\u003e\n\u003cli\u003eKotagiri, P., Chembolli, D., Ryan, J., Hughes, P. D. \u0026amp; Toussaint, N. D. 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Effects of Bacterial Urinary Tract Infection on Clinical Outcome and Survival of Kidney Transplant Patients. \u003cem\u003eTransplant Proc\u003c/em\u003e \u003cstrong\u003e54\u003c/strong\u003e, 1262-1269 (2022). https://doi.org/10.1016/j.transproceed.2022.03.031\u003c/li\u003e\n\u003cli\u003eSampogna, G., Grasso, A. \u0026amp; Montanari, E. Expandable metallic ureteral stent: indications and results. \u003cem\u003eMinerva Urol Nefrol\u003c/em\u003e \u003cstrong\u003e70\u003c/strong\u003e, 275-285 (2018). https://doi.org/10.23736/s0393-2249.18.03035-7\u003c/li\u003e\n\u003cli\u003eKhoo, C. C., Abboudi, H., Cartwright, R., El-Husseiny, T. \u0026amp; Dasgupta, R. Metallic Ureteric Stents in Malignant Ureteric Obstruction: A Systematic Review. \u003cem\u003eUrology\u003c/em\u003e \u003cstrong\u003e118\u003c/strong\u003e, 12-20 (2018). https://doi.org/10.1016/j.urology.2018.01.019\u003c/li\u003e\n\u003cli\u003ePapatsoris, A. G. \u0026amp; Buchholz, N. 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The thermo-expandable metallic ureteric stent: an 11-year follow-up. \u003cem\u003eBJU Int\u003c/em\u003e \u003cstrong\u003e103\u003c/strong\u003e, 372-376 (2009). https://doi.org/10.1111/j.1464-410X.2008.08018.x\u003c/li\u003e\n\u003cli\u003eMazzon, G.\u003cem\u003e et al.\u003c/em\u003e Long-term Outcomes of Minimally Invasive Rendezvous Procedures to Treat Complex Ureteric Strictures and Injuries. \u003cem\u003eEur Urol Open Sci\u003c/em\u003e \u003cstrong\u003e49\u003c/strong\u003e, 53-59 (2023). https://doi.org/10.1016/j.euros.2022.12.014\u003c/li\u003e\n\u003cli\u003eXu, G.\u003cem\u003e et al.\u003c/em\u003e Use of Self-Expanding Metallic Ureteral Stents in the Secondary Treatment of Ureteral Stenosis Following Kidney Transplantation. \u003cem\u003eJ Endourol\u003c/em\u003e \u003cstrong\u003e29\u003c/strong\u003e, 1199-1203 (2015). https://doi.org/10.1089/end.2015.0188\u003c/li\u003e\n\u003cli\u003eSedigh, O.\u003cem\u003e et al.\u003c/em\u003e Self-Expandable Covered Metallic Stent (UVENTA) to Treat a Ureteral Stricture After Renal Transplant: A Case Report. \u003cem\u003eExp Clin Transplant\u003c/em\u003e \u003cstrong\u003e18\u003c/strong\u003e, 116-119 (2020). https://doi.org/10.6002/ect.2017.0197\u003c/li\u003e\n\u003cli\u003eSalamanca-Bustos, J. J.\u003cem\u003e et al.\u003c/em\u003e Initial Experience in the Use of Novel Auto-expandable Metal Ureteral Stent in the Treatment of Ureter Stenosis in Kidney Transplanted Patients. \u003cem\u003eTransplant Proc\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 587-590 (2018). https://doi.org/10.1016/j.transproceed.2017.09.048\u003c/li\u003e\n\u003cli\u003eZhong, Q.\u003cem\u003e et al.\u003c/em\u003e Initial experiment of self-expanding metal ureteral stent in recurrent ureteral stenosis after kidney transplantation. \u003cem\u003eAm J Transplant\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 1983-1984 (2021). https://doi.org/10.1111/ajt.16444\u003c/li\u003e\n\u003cli\u003eCao, C.\u003cem\u003e et al.\u003c/em\u003e Temporary Covered Metallic Ureteral Stent Placement for Ureteral Strictures following Kidney Transplantation: Experience in 8 Patients. \u003cem\u003eJ Vasc Interv Radiol\u003c/em\u003e \u003cstrong\u003e31\u003c/strong\u003e, 1795-1800 (2020). https://doi.org/10.1016/j.jvir.2020.04.004\u003c/li\u003e\n\u003cli\u003eBoyvat, F.\u003cem\u003e et al.\u003c/em\u003e Memokath metallic stent in the treatment of transplant kidney ureter stenosis or occlusion. \u003cem\u003eCardiovasc Intervent Radiol\u003c/em\u003e \u003cstrong\u003e28\u003c/strong\u003e, 326-330 (2005). https://doi.org/10.1007/s00270-004-0028-2\u003c/li\u003e\n\u003cli\u003eBach, C.\u003cem\u003e et al.\u003c/em\u003e Endourological management of ureteric strictures after kidney transplantation: Stenting the stent. \u003cem\u003eArab J Urol\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 165-169 (2011). https://doi.org/10.1016/j.aju.2011.08.001\u003c/li\u003e\n\u003cli\u003eBach, C.\u003cem\u003e et al.\u003c/em\u003e A self-expanding thermolabile nitinol stent as a minimally invasive treatment alternative for ureteral strictures in renal transplant patients. \u003cem\u003eJ Endourol\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e, 1543-1545 (2013). https://doi.org/10.1089/end.2013.0180\u003c/li\u003e\n\u003cli\u003eTreacy, P. J., Rastinehad, A. R., Imbert de la Phalecque, L., Albano, L. \u0026amp; Durand, M. Endoureteral Management of Renal Graft Ureteral Stenosis by the Use of Long-Term Metal Stent: An Appealing Treatment Option. \u003cem\u003eJ Endourol Case Rep\u003c/em\u003e \u003cstrong\u003e2\u003c/strong\u003e, 155-158 (2016). https://doi.org/10.1089/cren.2016.0084\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Basal Patients Characteristics\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"737\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eN/Age/Sex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 161px;\"\u003e\n \u003cp\u003eLocalitation/Length(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eStent Size(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003eCre(\u0026mu;mol/L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eRPW(mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eTreatment-pre\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eComplications\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1/33/F\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 161px;\"\u003e\n \u003cp\u003eDistal/10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e20.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eD-J Stent,\u003c/p\u003e\n \u003cp\u003eNephrostomy,\u003c/p\u003e\n \u003cp\u003eballoon dilation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eHypertension\u003c/p\u003e\n \u003cp\u003eUTIs\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e2/35/F\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 161px;\"\u003e\n \u003cp\u003eDistal/10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e173\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e19.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eD-J Stent,\u003c/p\u003e\n \u003cp\u003eNephrostomy,\u003c/p\u003e\n \u003cp\u003eballoon dilation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eUTIs\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e3/40/F\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 161px;\"\u003e\n \u003cp\u003eDistal/40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e243\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e13.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eD-J Stent,\u003c/p\u003e\n \u003cp\u003eNephrostomy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eHypertension,\u003c/p\u003e\n \u003cp\u003eUTIs,\u003c/p\u003e\n \u003cp\u003eHyperuricemia\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e4/57/F\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 161px;\"\u003e\n \u003cp\u003eDistal/50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e145\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e16.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eD-J Stent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eHypertension,\u003c/p\u003e\n \u003cp\u003eUTIs,\u003c/p\u003e\n \u003cp\u003eOsteoporosis,\u003c/p\u003e\n \u003cp\u003eGERD\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e5/61/F\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 161px;\"\u003e\n \u003cp\u003eDistal/20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e259\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e14.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eD-J Stent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eHypertension,\u003c/p\u003e\n \u003cp\u003eUTIs,\u003c/p\u003e\n \u003cp\u003eShingles\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e6/42/F\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 161px;\"\u003e\n \u003cp\u003eDistal/50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e8.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eD-J Stent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eHypertension,\u003c/p\u003e\n \u003cp\u003eUTIs,\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCre= creatinine; Hb= hemoglobin; RPW= renal pelvis width\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Characteristics of Metal Stents Used in Last Decade\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"737\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eStudy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003ePatients\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eType of stent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eFollow-up(months)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 293px;\"\u003e\n \u003cp\u003eCharacteristics\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eGuibin Xu\u003csup\u003e20\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eAnDaXing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e13-86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 293px;\"\u003e\n \u003cp\u003eTechnically success rate (100%), lower urinary-tract symptoms (6/7), ipsilateral flank pain (4/7),\u0026nbsp;urothelial hyperplasia-induced obstruction (1/7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eOmid Sedigh\u003csup\u003e21\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eUVENTA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e12\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 293px;\"\u003e\n \u003cp\u003eNo complications, renal function remained stable and there were no signs of recurrence after removed.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eJ J Salamanca-Bustos\u003csup\u003e22\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eUVENTA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e4-38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 293px;\"\u003e\n \u003cp\u003eTechnically success rate (100%), renal graft loss (1/5), UTI (1/5),\u0026nbsp;hydronephrosis correction rate (100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eQiang Zhong\u003csup\u003e23\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eAllium\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e5-17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 293px;\"\u003e\n \u003cp\u003eSuccess rate (86%), release of obstruction (100%), stent migration (2/8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eChuanwu Cao\u003csup\u003e24\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eUrexel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e2-27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 293px;\"\u003e\n \u003cp\u003eHematuria (2/8), pain (3/8), stent migration (2/8), urothelial hyperplasia (2/8), recurrence (2/8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e Characteristics of Memokath051 Used to Treat Transplant Ureteral Stenosis\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"737\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eStudy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003ePatients\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003eFollow-up(months)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 397px;\"\u003e\n \u003cp\u003eCharacteristics\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eFatih Boyvat\u003csup\u003e25\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e18\u0026ndash;21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 397px;\"\u003e\n \u003cp\u003eTechnically success rate (100%), stent migration (1/4), UTI (1/4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eChristian Bach\u003csup\u003e26\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 397px;\"\u003e\n \u003cp\u003eSuccessfully replace a previously placed metal self-expanding mesh stent without the previous problems of encrustation and endothelial ingrowth.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003eChristian Bach\u003csup\u003e27\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e55（mean）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 397px;\"\u003e\n \u003cp\u003eLong-term success rate (87%), stent migration (1/8),\u0026nbsp;spontaneous\u003c/p\u003e\n \u003cp\u003eresolution of the stricture (3/8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003ePatrick-Julien Treacy\u003csup\u003e28\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 123px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 397px;\"\u003e\n \u003cp\u003eOne week after surgery, there is a major decrease of serum creatinine and a complete restriction of the pelvic dilation, and no complications during follow-up.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\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":"Ureteral Stenosis, Kidney Transplantation, Self-expandable Metallic Stents, Endoscope","lastPublishedDoi":"10.21203/rs.3.rs-7341939/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7341939/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eUreteral stenosis is the most common urological condition after renal transplantation that requires extensive technical knowledge and experience in placing thermo-expandable metal stents using a modified rendezvous procedure. The purpose of this study is to analyze the efficacy and safety of this procedure. A total of six female patients underwent a modified rendezvous operation to receive thermo-expandable metal stents between 2022 and 2024. Postoperative follow-up was undertaken for 1 to 24 months. All stents were successfully placed with a mean operative time of 173.0 minutes and an average hospital stay of 8.8 days. Considerable improvements in hydronephrosis were noted among all patients with no statistically significant variation in mean creatinine levels between preoperative and postoperative periods (P\u0026thinsp;=\u0026thinsp;0.937). Despite a statistical difference in hemoglobin levels between preoperative measurements and those taken on the first postoperative day (P\u0026thinsp;=\u0026thinsp;0.022), its clinical significance remains unclear. Moreover, we observed no statistically significant difference in preoperative versus postoperative leukocyte counts (P\u0026thinsp;=\u0026thinsp;0.410). All stents currently remain suitably positioned and functionally stable. In summary, a modified rendezvous procedure in this study demonstrates both safety and efficacy in treating ureteral stenosis after renal transplantation using thermo-expandable metal stents.\u003c/p\u003e","manuscriptTitle":"Modified Rendezvous Procedures for the Placement of Thermo- expandable Metallic Stents in the Treatment of Ureteral Stenosis in Renal Transplant Patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-12 14:32:59","doi":"10.21203/rs.3.rs-7341939/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":"62110776-0af8-4ab1-a880-9d19538d2727","owner":[],"postedDate":"September 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":54312702,"name":"Health sciences/Diseases"},{"id":54312703,"name":"Health sciences/Medical research"},{"id":54312704,"name":"Health sciences/Urology"}],"tags":[],"updatedAt":"2026-02-20T09:40:39+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-12 14:32:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7341939","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7341939","identity":"rs-7341939","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}