The Resonance and the Allium ureteral stents in the treatment of non-malignant refractory ureterostenosis

Risk factors for migration of retrievable covered expandable metallic stent in patients with persistent benign ureter strictures

PURPOSE

The purpose of this study is to evaluate the incidence, risk factors, and salvage management of retrievable covered expandable metallic stent (RCEMS) migration in patients with persistent benign ureter strictures.

MATERIALS AND METHODS

A retrospective study was performed on 117 consecutive patients who underwent implantation of RCEMS. Univariate and multivariate analyses were used to identify prognostic factors for stent migration, including stricture location and length, hydronephrosis-cortex ratio, ureteral dilation, and the diameter of the narrowest portion of the stricture.

RESULTS

Stent migration occurred in 22 (19.5%) of 113 patients who met inclusion criteria. Of the 22 patients, 16 (72.7%) had ordinary ureteral stricture, 3 (13.6%) had stricture in transplanted kidneys, and 3 patients (13.6%) had ureter stricture in orthotopic neobladders. The mean creatinine for the entire cohorts showed significant improvement (p = 0.038). Multivariate analysis identified the following prognostic factors for migration: distal ureteral stricture (p = 0.006), patients who underwent balloon dilation (p = 0.003), hydronephrosis-cortex ratio ≧10 (p = 0.017), larger diameter of wasting of RCEMS (p < 0.001), and patients with a shorter stricture length (p = 0.006). Salvage management was required in 4 of the 22 patients. The strictures in the remaining 18 patients improved with observation.

CONCLUSIONS

Stent migration is more likely to occur in patients with the five prognostic factors mentioned above. Our study developed a nomogram to predict stent migration in patients with ureteral strictures treated using RCEMS.

Metal ureteral stents for ureteral stricture: 2 years of experience with 246 cases

BACKGROUND

Metal ureteral stents (MUS) has gained popularity as an endoscopic treatment alternative for the management of ureteral strictures. The aim of this study was to evaluate the safety, efficacy, and tolerability of MUS for treating ureteral strictures and to identify any factors that could influence the success of this intervention.

METHODS

This study is a prospective analysis of the efficacy and safety of MUS for treating ureteral strictures in a single-center setting. The study enrolled 246 patients who had been diagnosed with ureteral strictures and had undergone MUS placement between January 2019 and July 2021. The patients were followed-up for a duration of 2 years.

RESULTS

The overall success rate of MUS placement was 71.7%. Furthermore, the success rate of ureteral strictures after kidney transplantation (78.2%) was significantly higher than common ureteral strictures (73.0%) or recurrent ureteral strictures (67.6%). Additionally, postsurgery, there was a considerable reduction in hydronephrosis volume (68.9±96.1 vs. 32.1±48.8 cm 3 ), blood creatinine level (103.7±49.8 vs. 94.4±47.5 mol/l) and urea nitrogen level (6.7±7.2 vs. 5.1±2.4 mmol/l). The study also reported that the rate of adverse events associated with MUS was relatively low, included hematuria (7.9%), pain (6.8%), urinary tract infection (6.4%), and lower urinary tract symptoms (5.3%).

CONCLUSIONS

MUS appear to be a safe and effective treatment option for ureteral strictures, with a high success rate and low complication rate. These results have important implications for the management of ureteral strictures and can help guide clinical decision-making in the selection of treatment options.

Allium® ureteral stent, a new player in the treatment of ureteral stenosis: a prospective cohort study

INTRODUCTION AND OBJECTIVES

Ureteral stricture is a chronic condition that can result in the obstruction of urinary drainage from the affected renal unit, leading to loss of renal function. Treatment methods can be categorized into two main headings: endourological and reconstructive procedures. We aimed to investigate the efficacy and safety of the self-expandable Allium® ureteral stent, which has been used in the minimally invasive treatment of ureteral stenosis in recent years.

MATERIALS AND METHODS

Twenty patients who were applied Allium® ureteral stent between 2017 and 2021 included in the study. The demographic and clinical characteristics of the patients, the details of the treatments applied to the patients, the perioperative and postoperative complications, the treatments applied for the complications and the findings in the follow-up were recorded and evaluated prospectively.

RESULTS

Etiology included urolithiasis in 16 patients (80%), malignancy in 3 patients (15%), and a previous gynecological operation in 1 patient (5%). Stent obstruction was found to be the most common complication in 3 patients (15%). Stent migration was the second most common complication in 2 patients (10%). Our follow-up continues with 15 patients without stent-related complications and stent obstruction. The mean follow-up period was 28 ± 15.7 months.

CONCLUSIONS

Allium ureteral stent is an effective and reliable method in the minimally invasive treatment of ureteral stricture with complications seen at acceptable rates and ease of treatment in the management of complications.

Evaluation of Renal Function and Stent Durability Following Resonance Stent Placement for Benign Disease

Introduction: The metal-based Resonance stent (RS) has traditionally been placed in patients with malignant ureteral obstruction; as such, the long-term utility of RS among patients with benign ureteral obstruction (BUO) remains underinvestigated. Methods: We retrospectively reviewed our database for patients with BUO who underwent RS placement between 2010 and 2020. The impact of chronic RS placement on renal function was evaluated by estimated serum creatinine-based glomerular filtration rate (eGFR), furosemide renal scan, and CT-based renal parenchymal volume measurement. The number of and reason for RS stent exchanges during the follow-up period, incidence of encrustation, and the average indwell time were recorded. A cost analysis of placing the RS vs a polymeric stent was performed. Results: Among 43 RS patients with BUO, at a mean follow-up of 26 months, there was no change in eGFR (p = 0.99), parenchymal volume (p = 0.44), or split renal function of the stent-bearing side on renal scan (p = 0.48). The mean RS indwell time was 9.7 months. Eleven patients (26%) underwent premature stent replacement (6 cases) or removal (5 cases). Stents in 9 patients (32%) were encrusted, of which 4 (44%) required laser lithotripsy. Overall, 25 patients (58%) and 12 patients (28%) had a mean stent indwell time of ≥6 months and ≥12 months, respectively. Placing an RS resulted in a 52%, 37%, and 5.6% cost reduction compared with a regular polymeric stent placement, where it was exchanged every 6, 4, or 3 months, respectively. Conclusions: RS deployment in the patient with a BUO results in cost-effective maintenance of renal function and of renal parenchymal volume at a mean follow-up of 2 years; however, only 28% of patients fulfilled the 1-year criterion for RS indwell time.

Research progress of biomaterials and innovative technologies in urinary tissue engineering

Substantial interests have been attracted to multiple bioactive and biomimetic biomaterials in recent decades because of their ability in presenting a structural and functional reconstruction of urinary tissues. Some innovative technologies have also been surging in urinary tissue engineering and urological regeneration by providing insights into the physiological behavior of the urinary system. As such, the hierarchical structure and tissue function of the bladder, urethra, and ureter can be reproduced similarly to the native urinary tissues. This review aims to summarize recent advances in functional biomaterials and biomimetic technologies toward urological reconstruction. Various nanofirous biomaterials derived from decellularized natural tissues, synthetic biopolymers, and hybrid scaffolds were developed with desired microstructure, surface chemistry, and mechanical properties. Some growth factors, drugs, as well as inorganic nanomaterials were also utilized to enhance the biological activity and functionality of scaffolds. Notably, it is emphasized that advanced approaches, such as 3D (bio) printing and organoids, have also been developed to facilitate structural and functional regeneration of the urological system. So in this review, we discussed the fabrication strategies, physiochemical properties, and biofunctional modification of regenerative biomaterials and their potential clinical application of fast-evolving technologies. In addition, future prospective and commercial products are further proposed and discussed.

Long-term maintenance treatment of recurrent ureteropelvic junction obstruction with covered metallic ureteral stent

Whether or not the covered metallic ureteral stent can be used as maintenance treatment for recurrent ureteropelvic junction obstruction (UPJO) after pyeloplasty is unknown. Therefore, this study aims to analyze its feasibility. We retrospectively analyzed the records of 20 patients with recurrent UPJO who were treated with the covered metallic ureteral stents from March 2019 to June 2021 at our institution. Then, we assessed their renal function, stent patency and stent-related quality of life by the blood creatinine, renal ultrasound (or computed tomography), and the Chinese version of the ureteral symptom score questionnaire (USSQ). The last follow-up mean blood creatinine dropped from 0.98 ± 0.22 to 0.91 ± 0.21 mg/dL (P = .04), and the median renal pelvic width was reduced from 3.25 (3.10) to 2.00 (1.67) cm (P = .03) compared with the preoperative conditions. Meanwhile, the last follow-up mean USSQ total score of the covered metallic ureteral stent among the 16 patients with preoperative indwelling double-J ureteral stent was 78.56 ± 14.75, significantly lower than the preoperative USSQ total score, which was 102.25 ± 5.57 (P < .001). During the median duration of follow-up of 27.00 (18.00) months, 85% (17/20) of patients maintained unobstructed drainage from the renal pelvis to the ureter. Stent-related complications occurred in 7 patients, 3 of which failed because of complications, including stent migration (1 patient), stent encrustation (1 patient), and stent-related infection (1 patient). The covered metallic ureteral stent is feasible for the long-term maintenance treatment of recurrent UPJO after pyeloplasty.

[Long-term efficacy evaluation of coated metal stent implantation for ureteroscopic lithotripsy related refractory ureteral stricture]

OBJECTIVE

To comprehensively evaluate the long-term efficacy and safety of coated metal stent implantation for ureteroscopic lithotripsy related refractory ureteral stricture (URL-rUS).

METHODS

Electronic medical records of 30 patients (31 affected renal units) receiving coated metal stent implantation for URL-rUS from Sept. 2018 to Aug. 2021 at Peking University People' s Hospital were reviewed for analysis. Coated metal stents were implanted in retrograde approach via ureteroscope. Last outpatient follow-up was set as endpoint. Baseline information, stricture characteristics and decompression strategy before coated metal stent implantation were retrospectively collected. Serum creatinine (Scr) concentration and renal pelvis width (RPW) were used as renal function indicators. Peri-operative and long-term complications and according outcomes were recorded. For the patients who had double J tubes implanted for drainage before operation, Ureteral Stent Symptom Questionnaire (USSQ) was applied to evaluate the stent-related discomforts and quality of life (QoL) before and after surgery. Data analysis was conducted with SPSS (version 25.0; SPSS, Chicago, IL, USA).

RESULTS

Totally 30 patients with 31 affected renal units were included. All the patients previously underwent unsuccessful traditional endoscopic balloon dilation or endoureterotomy before receiving coated metal stent implantation. The mean age was (45.5±9.3) years old. The median follow-up time were 14 (6-36) months. All coated metal stents were successfully placed with a median duration of 60 (30-195) min. No severe peri-operative complications occurred. At endpoint, 28 (90.3%) sides of coated metal stents remained unobstructed with a longest indwelling time of 36 months. Causes of failures included stent migration (1 case, 3.2%), encrustation (1 case, 3.2%) and repeated stent related urinary tract infection (1 case, 3.2%). When compared with the baseline, significant reductions were observed in both Scr concentration and RPW at endpoint [(90.7±19.5) mmol/L vs. (83.1±18.5) μmol/L, P < 0.01, for Scr; (2.5±1.3) cm vs. (1.9±0.8) cm, P < 0.01, for RPW], indicating good preservation of renal function and remission of hydronephrosis. For 26 patients with double J stents before operation, significant reduction of USSQ average score (100.4±6.6 vs. 82.1±4.9, P < 0.01) evidenced better life quality preserving ability of coated metal stent versus double J stent.

CONCLUSION

Coated metal stent implantation is a safe and minimally invasive management of ureteral stricture providing a satisfying long-term patency rate, after which the patients' quality of life and renal function could be both improved. This method could serve as a promising alternative long-term maintenance treatment option for patients with URL-US, especially when traditional endoscopic interventions failed.

Extra-anatomical stents in benign ureteric obstruction; experience and outcomes

Objectives To present our experience with the Patterson-Forester extra-anatomic stent (EAS, Cook Medical) in patients with benign ureteric obstruction. Utilising an EAS in complex ureteric obstruction can have a significant positive impact on quality of life as a result of removing external drainage devices. Materials and methods Between November 2012 and January 2021 10 patients underwent 33 EAS procedures. All patients had benign ureteric obstruction. Mean age at primary procedure was 58 years (range 43-63). Median follow-up was 27.5 months (range 11-100). Results Eight patients were successfully managed with EAS, with 6 patients continuing to have routine EAS exchanges. Two patients had the distal end exteriorised due to refractory bladder symptoms. There were three short-term failures; the distal end migrated out of the bladder requiring reinsertion one week later; one patient developed urosepsis requiring intravenous antibiotics and the stent removing within 30 days; one proximal stent migrated resulting in cutaneous erosion. The patient is now awaiting further EAS insertion. Conclusion The Patterson-Forester EAS is another tool in the endourologists' armamentarium when managing complex ureteric obstruction. In appropriately selected patients, it can improve their quality of life and is a durable long-term strategy in benign obstruction.