Metallic Ureteral Stents Research Articles

Preparation and characterization of PLGA nano-drug delivery system co-loaded with tranilast/gallium phytate for stent coating

The implantation of bare metal ureteral stents may lead to bacterial colonization and scar hyperplasia. To effectively address these issues, PLGA nanoparticles co-loaded with tranilast and gallium phytate (PG-TRL-PLGA-NPs) were prepared using an emulsifying solvent volatilization technique. The PG-TRL-PLGA-NPs possess a dual function of antibacterial and proliferation inhibition, which could be used for stent functional coating. The PG-TRL-PLGA-NPs displayed a regular spherical morphology with a smooth surface, and average particle size of 163 ± 1.37 nm, Zeta potential of −16.09 mV, drug loading capacity of 9.4 ± 0.6%, and encapsulation efficiency of 97.5 ± 0.4% could be achieved. FTIR, XRD, and DSC analysis demonstrated that PG-TRL-PLGA-NPS was successfully nano-encapsulated without chemical reaction among TRL, PG, and PLGA. In vitro release profiles of TRL and gallium ions from PG-TRL-PLGA-NPs exhibited a sustained-release effect, with 89.7 ± 0.9% and 3.2 ± 0.15 mg/L released in 14 days, respectively. Furthermore, it was observed the potent antibacterial activity (against S. aureus and E. coli.) of PG-TRL-PLGA-NPs, also significantly inhibited SV-HUC-1 cell proliferation through experiments involving cell migration, cell cycle, and apoptosis studies. These results provide valuable insights into the stent coatings of PG-TRL-PGLA NPs with potential functions of antibacterial and proliferative inhibitory.

Cost‐effectiveness of Resonance® metallic ureteral stent compared with standard polyurethane ureteral stents in malignant ureteric obstruction: A cost‐utility analysis

AbstractBackgroundMalignant ureteral obstruction (MUO) is a frequent challenge for urologists. Patients have poor prognoses, treatment aims to improve quality‐of‐life while optimising renal function. Standard practice in the United Kingdom is to use polyurethane stents, which require frequent surgical replacements for blockages and encrustation. More durable metallic stents are available, although these incur an increased initial purchase price.AimsWe aim to assess whether the use of polyurethane double‐J (JJ) or metallic stent, Resonance® is more cost‐effective for managing MUO in the UK healthcare setting.MethodsA Markov model was parameterised to 5 years with costs and health‐related quality‐of‐life consequences for treating MUO with Resonance metallic stent (Cook Medical), versus standard JJ stents, from the UK care system perspective, with 3.5% discounting. Deterministic and probabilistic sensitivity analyses were undertaken to assess the effect of uncertainty.ResultsOver 5 years, approximately four fewer repeat surgical interventions were estimated in the metallic stent arm compared with the JJ stent, driving a 23.4% reduction in costs. The mean estimates of costs and benefits indicate that treatment of MUO with Resonance for 5 years is dominant over JJ stents. Over 5 years a cost‐saving of £2164.74 and a health gain of +0.046 quality‐adjusted life years (QALYs) per patient is estimated. With a maximum willingness to pay of £20 k per QALY, a net monetary benefit (NMB) of £3077.83 is estimated. Probabilistic sensitivity analysis at a willingness to pay threshold of £20 000 indicates an 89.3% probability of Resonance being cost‐effective over JJ stents. Within 1‐year savings of £726.53 are estimated driven by a reduction of two fewer repeat surgical interventions when using the metallic stent.ConclusionsResonance metallic stents for the treatment of MUO reduce the number of repeat procedures and could be a cost‐effective option for the treatment, potentially offering efficiencies to the healthcare system.

A commentary on 'Metal ureteral stents for ureteral stricture: 2 years of experience with 246 cases'.

A commentary on 'Metal ureteral stents for ureteral stricture: 2 years of experience with 246 cases'.

Allium ureteral stent for refractory ureteral stricture: A single-center study

Purpose: This study aims to investigate the efficacy and safety of Allium metallic ureteral stents in treating patients with refractory ureteral strictures. Materials and methods: A total of 13 patients with refractory ureteral strictures were prospectively enrolled in the study. After ureteral balloon dilation, an Allium stent was inserted into the ureter through the stricture. Serum blood urea nitrogen and creatinine levels, kidney-ureter-bladder x-ray, and renal ultrasonography reports were evaluated preoperatively, 3 months after the procedure, and at the last outpatient visit. Treatment success was defined as improvement in both renal function and the grade of hydronephrosis. Improvement was defined as the enhancement of renal function without the resolution of hydronephrosis. Adverse events were recorded. Results: The median (interquartile range [IQR]) age of the patients was 63 (46–76) years. The median (IQR) follow-up was 15 (13.5–21) months. Treatment success and improvement were noted in 9 (69.2%) and 3 (23.1%) patients, respectively. Compared with the preoperative levels, the median (IQR) serum creatinine levels were significantly improved at 3 months after the operation (1.6 [1.25–2.85] versus 1.2 [1.05–2.05]; P = 0.02) and at the last visit (1.6 [1.25–2.85] versus 1.2 [1.05–1.8]; P = 0.02). Stent migration and encrustation were noted in 3 (23.1%) and 1 (7.7%) patients, respectively. Conclusion: Allium ureteral stents are safe and effective for patients with refractory ureteral strictures.

Reply to "A commentary on 'Self-expanding metal ureteral stent for ureteral stricture: experience of a large- scale prospective study from a high-volume center - cross-sectional study' (Int J Surg 2021; 95: 106161)".

Reply to "A commentary on 'Self-expanding metal ureteral stent for ureteral stricture: experience of a large- scale prospective study from a high-volume center - cross-sectional study' (Int J Surg 2021; 95: 106161)".

Stent-ception: implementation of soft double-J stents in the ureteric Memokath-051<sup>TM</sup> in bilateral ureteric stricture post radiotherapy for advanced prostate cancer

Narrowing of ureter can be due to malignant or benign causes. Temporary double-J (DJ) stents, various metallic stent designs, or definitive corrective surgery can be the options management for ureteric stricture. As an alternative from DJ stents, Memokath-051TM (MMK-051TM) can be inserted in strictured ureters post radiotherapy for advanced prostate cancer patients. We present a case of an advanced prostate cancer which bilateral DJ Stents placed within MMK-051TM. A 76-year-old man with underlying hormone sensitive advanced prostate cancer completed radiotherapy. Post radiotherapy he developed bilateral ureteric strictures and bilateral DJ stents inserted. He had to underwent multiple change of stents due to blockage. Patient had MMK-051TM inserted, however complicated with blockage due to encrustation. Improvisation method done by putting the bilateral DJ stents within the MMK-051TM. Patient had no more blockage of MMK-051TM after the placement of DJ stents within it. However, patient succumbed to death a year after the last procedure. Our case report highlighted encrustation of metallic ureteric stents and a novel approach to overcome this problem. Introduction of additional DJ stents not only reduced the incidence of MMK-051TM blockage but also improved the quality of life of the patient.

Understanding the corrosion of Mg alloys in in vitro urinary tract conditions: A step forward towards a biodegradable metallic ureteral stent

Ureteral stents play a fundamental role in modern time urology. However, following the deployment, stent-related symptoms are frequent and affect patient health and quality of life. Using biodegradable metals as ureteral stent materials have emerged as a promising strategy, mainly due to the improved radial force and slower degradation rate expected. Therefore, this study aimed to characterize different biodegradable metals in urinary tract environment to understand their propensity for future utilization as base materials for ureteral stents. The corrosion of 5 Mg alloys – AZ31, Mg-1Zn, Mg-1Y, pure Mg, and Mg-4Ag – under simulated urinary tract conditions was accessed. The corrosion layer of the different alloys presented common elements, such as Mg(OH)2, MgO, and phosphate-containing products, but slight variations in their chemical compositions were detected. The corrosion rate of the different metals varied, which was expected given the differences in the corrosion layers. On top of this, the findings of this study highlighted the significant differences in the samples' corrosion and corrosion layers when in stagnant and flowing conditions. With the results of this study, we concluded that Mg-1Zn and Mg-4Ag presented a higher propensity for localized corrosion, probably due to a less protective corrosion layer; Mg-4Ag corroded faster than all the other four alloys, and Mg-1Y stood out due to its distinct corrosion pattern, that showed to be more homogeneous than all the other four samples, making this one more attractive for the future studies on biodegradable metals.

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

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. 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. 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, post-surgery, there was a considerable reduction in hydronephrosis volume (68.9±96.1 vs. 32.1±48.8cm3), blood creatinine level (103.7±49.8 vs. 94.4±47.5mol/L) and urea nitrogen level (6.7±7.2 vs. 5.1±2.4mmol/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%). 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.

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.

A commentary on 'Self-expanding metal ureteral stent for ureteral stricture: experience of a large-scale prospective study from a high-volume center-cross-sectional study' (Int J Surg 2021; 95: 106161).

A commentary on 'Self-expanding metal ureteral stent for ureteral stricture: experience of a large-scale prospective study from a high-volume center-cross-sectional study' (Int J Surg 2021; 95: 106161).

REVIEW ON COMPLICATIONS AND ADVERSE EFFECTS OF METALLIC URINARY STENTS.

Urinary stents, be it urethral or ureteral, polymeric, metallic or biodegradable, are one of the most frequently used tools in urology and they have been used for decades in prophylactic and therapeutic setting. Although relatively low invasive, they are prone to complications and adverse effects so much that complication rates up to 100% have been described. Many reviews have focused either on specific groups of patients or particular stent types, materials or designs but so far, no comprehensive review on complications has been published. To tackle this issue, a working group was set up within ENIUS (European Network of multidisciplinary research to Improve Urinary Stents) tasked with literature search in order to screen for and systematically review published stent complications in urethra (male only) and ureters (polymeric and metallic ureteral stents in both sexes) when used in obstructed systems. In this paper, we review, catalogue and summarize complications published for metallic urethral and ureteral stents.

Use of metallic ureteric stents for chronic ureteric obstruction and its association with value-based care.

We aimed to compare the real-world data and our clinical experience with metallic stents (MSs) and conventional polymeric stents (PSs) in the management of both malignant and benign chronic ureteric obstruction (CUO), in terms of clinical outcomes and costs. Clinical data from our institution, including outcomes for all ureteric stents inserted for long-term management of CUO from all causes from 2014 to 2017, were retrospectively reviewed and compared between the MS and PS episodes. A total of 247 stents were placed in 63 patients with CUO over the 4-year study period. Of these, 45 stents were MSs. There was no significant difference in all baseline characteristics between the MS and PS groups, except for the aetiology of obstructive cause. Mean indwelling stent duration was significantly greater for MS than for PS (228.6 ± 147.0 vs. 146.1 ± 66.0 days, P < 0.001), thereby leading to lower average number of stent changes per year in the MS group compared to the PS group (1.4 vs. 6.3 times, respectively). Despite the higher unit cost of MS compared to PS, there was no significant mean cost difference overall (cost per dwelling day SGD 7.82 ± SGD 10.44 vs. SGD 8.23 ± SGD 20.50, P = 0.888). Resonance MS is a better option than PS to manage CUO from malignant and benign causes because its significantly longer indwelling time mitigates the higher unit cost of the stent. It potentially reduces the number of procedures and operations in patients. Thus, it should be considered for all patients with CUO requiring long-term ureteric drainage.

UP22 - Resonance® metallic ureteral stent as a real alternative for chroni urinary diversion. Results in our center.

UP22 - Resonance® metallic ureteral stent as a real alternative for chroni urinary diversion. Results in our center.

MP044 - First experience and outcome data of Allium™ coated metal ureteral stent in treatment of ureteral strictures - a retrospective study

MP044 - First experience and outcome data of Allium™ coated metal ureteral stent in treatment of ureteral strictures - a retrospective study

Outcome of metal ureteral stents for ureteral obstruction due to malignancy

Outcome of metal ureteral stents for ureteral obstruction due to malignancy

Initial Experience of Self-Expanding Metal Ureteral Stent in Recurrent Ureteral Stricture After Ureteroplasty.

Background: The aim of this prospective study was to assess the safety and effectiveness of self-expanding metal ureteral stent (MUS) for the treatment of recurrent ureteral stricture after ureteroplasty.Methods: We prospectively included 24 patients who underwent MUS implantation between February 2019 and August 2020. The inclusion criteria for the procedure were recurrent ureteral strictures after ureteroplasty. A paired T test was used to compare continuous variables before and after surgery.Results: A total of 24 patients were finally included in this study. The stricture site was most common on the proximal ureter 19 (79.2%), followed by distal ureter 4 (16.7%) and middle ureter 1 (4.2%). The median length of ureteral stricture is 2.5 (range 1–18) cm. The median operative time was 51.5 min, and the median hospital stay time after surgery was 3 days. Post-operative complication included pain 1 (4.2%), urinary tract infection 2 (8.3%) and hematuria 2 (8.3%). After a median follow-up of 12 months, 19/24 (83.3%) patients were clinically and radiologically successful. We endoscopically adjusted or exchanged the failed stents. The volume of hydronephrosis (124.7 ± 132.5 vs. 66.4 ± 73.2 cm3, P = 0.015), blood creatinine level (104.5 ± 45.4 vs. 80.1 ± 23.2 μmol/L, P = 0.044) and urea nitrogen level (6.9 ± 2.4 vs. 4.8 ± 1.5 mmol/L, P = 0.003) decreased significantly after a median follow-up of 12 months.Conclusions: MUS is a safe and effective way to manage recurrent ureteral strictures after ureteroplasty. This technique provides a new choice for the treatment of recurrent stricture.

Self-expanding metal ureteral stent for ureteral stricture: Experience of a large-scale prospective study from a high-volume center - Cross-sectional study

BackgroundThe management of ureteral stricture is still a challenge for urologists. The aim of this prospective study was to assess the safety and effectiveness of self-expanding metal ureteral stents (URS) in ureteral strictures. MethodsWe performed URS placement procedures for ureteral stricture from Jan 2019 to July 2020, and prospectively collect various data before and after the operation. A paired T test was used to compare continuous variables before and after surgery, binary logistic regression analysis was used to identify the independent risk predictors of surgical failure. ResultsA total of 147 patients with 157 renal units received successful placement of URS. The mean operative time was 70.0 min. After a median follow-up time of 15 months, 73.2% (115/157) of stents were kept in situ. The most common complication was hematuria (13, 8.8%), followed by urinary tract infection (11, 7.5%) and pain (8, 5.4%). The volume of hydronephrosis (67.9 ± 34.9 VS 34.9 ± 51.1 cm3, P = 0.0001), serum creatinine level (103.0 ± 54.5 VS 93.8 ± 45.1 μmol/L, P = 0.034) and blood urea nitrogen level (6.6 ± 6.7 VS 5.4 ± 2.4 mmol/L, P = 0.032) decreased significantly at last follow up when compared with baseline. Stricture of the distal ureter was an independent risk factor for stent failure (HR 1.77, 95% CI 1.15, 2.73, P = 0.009). ConclusionsURS was found to be safe and effective for ureteral strictures with a limited complications and good long-term results. For those who are not suitable for surgical reconstruction, the URS is an alternative management.

Metal stent for the ureteral stricture after surgery and/or radiation treatment for malignancy

BackgroundTo assess the efficacy and safety of self-expanding metal ureteral stent for the stricture following surgery and/or radiation for malignancy.MethodsWe performed 36 metal ureteral stent insertion procedures (32 patients) between May 2019 and June 2020. The main inclusion criterion was the patients with ureteral stricture due to surgery and/or radiation treatment for malignancy. The diagnosis of stricture was ascertained by history and radiographic imaging. The etiologies underlying the strictures were: surgery and/or radiation therapy for cervical and rectal cancer, surgery for ovarian cancer. The primary outcome was the stent patency rate, and the secondary outcomes were the postoperative complications and glomerular filtration rate (GFR). Stent patency was defined as stent in situ without evident migration, unanticipated stent exchange or recurrent ureteral obstruction. Cost analysis was calculated from stent cost, anesthesia cost and operating room fee.ResultsThe pre-metallic stent GFR was 22.53 ± 6.55 mL/min/1.73 m2. Eight patients were on double-J stents before insertion of metallic stents. The total annual cost of per patient in our study was $10,600.2 US dollars (range $9394.4–$33,527.4 US dollars). During a median follow-up time of 16 months (range 8–21 months), 27 cases (31 sides, 84%) remained stent patency. Twelve patients died from their primary malignancy carrying a patency stent. Stent migration was observed in 4 patients within 10 months after insertion. Ectopic stents were endoscopically removed and replaced successfully. Three stents were occluded, and no encrustation was seen in our study. Three and four patients had postoperative fever and gross hematuria, respectively. Infection was observed in 2 cases, mandating antibiotics therapy. In addition, postoperative volume of hydronephrosis postoperatively was significantly reduced compared with preoperation (54.18 ± 15.42 vs 23.92 ± 8.3, P = 0.019). However, no statistically significant differences regarding GFR, creatinine levels, blood urea nitrogen and hemoglobin existed between preoperation and last follow-up.ConclusionsThe current study demonstrated that metal ureteral stent is effective and safe in the treatment of stricture following surgery and/or radiation therapy for malignant cancer. Patients hydronephrosis could be improved by the stent placement.

746 Single-Centre Experience with Three Metallic Ureteric Stents (Allium URS, Memokath-051 and Resonance) for Chronic Ureteric Obstruction

Abstract Aim To evaluate efficacy of Allium URS, Memokath 051 and Resonance metallic ureteric stents as an alternative to polymer stents/nephrostomy in managing chronic ureteric obstruction (CUO). Method Retrospective analysis of consecutive patients with CUO managed with Allium URS, Memokath-051 or Resonance (September 2015/July 2020). Baseline patient variables (age, gender, underlying aetiology, ASA) and stricture characteristics (length, level, continuity) were recorded. Intra- and post-operative clinical and radiological follow-up assessments at 6 weeks, 3 months and then every 6 months, as well as any emergency attendances, were reviewed for placement success, stent complications, serum creatinine, and mortality. Outcomes included placement success rate, functional stent survival, and mean renal function. Results Overall, 129 stent insertion episodes (SIEs) (Allium URS: 23, Memokath 051: 48, Resonance: 58) occurred in 76 patients (Allium URS: 16; Memokath-051: 31; Resonance: 29). Placement success was high (Allium URS: 95.7%; Memokath-051 and Resonance: both 100%). Median functional stent survival was 11.4 months for Allium URS, 5.5 months for Memokath-051 and 11.7 months for Resonance. 47.8% of Allium URS SIEs (11/23), 64.6% of Memokath-051 SIEs (31/48) and 19% of Resonance SIEs (11/58) experienced complication (most frequently obstruction followed by migration and infection). There were no complications for Resonance SIEs for benign indication. In the first year following SIE, serum creatinine ranged from +21.3% to + 46.7% for Allium URS, -7.8% to + 8.9% for Memokath-051, and -9.4% to + 27.3% for Resonance. Conclusions Allium URS, Memokath 051 and Resonance metallic ureteric stents are all viable management options of CUO. Resonance was particularly efficacious for patients with benign aetiology.

Patency period of a metallic ureteral stent and its determinants in patients with malignant ureteral obstruction: a prospective review

BackgroundMalignant ureteral obstruction caused by extrinsic compression of a primary malignant tumour or by metastatic disease is an indicator of poor prognosis with a median life expectancy of about one year. We examined clinical outcomes following Resonance Metallic Ureteral Stent (Cook Medical, Bloomington, IN) placement in patients with malignant ureteral obstruction.MethodsThis was a prospective study of patients with malignant ureteral obstruction who underwent Resonance Metallic Ureteral Stent placement from April 2016 to March 2021. We registered 21 patients (27 collecting systems) with malignant ureteral obstruction and observed them prospectively. The patients first underwent polymer ureteral stent placement followed by replacement with a metallic ureteral stent one month later. Primary outcome was the metallic ureteral stent patency period based on both serum creatinine and the level of hydronephrosis; secondary outcomes were factors affecting patency period and stent-related complications such as symptoms of obstruction (flank pain), bladder irritation, haematuria, and urinary tract infection (presence or absence of fever).ResultsThe study comprised 21 patients (six men, 15 women) with a mean age of 72 years. The median stent patency period in days was not available (NA) (95% CI 210–NA) due to the inability to extract this value from the Kaplan–Meier curve because the event rate did not reach 50%, and the one-year patency rate was 59.2% (95% CI 23.2–82.9). A normal serum creatinine (0.65 to 1.07 mg/dL for men and 0.46 to 0.79 mg/dL for women) one week after polymer ureteral stent placement was a significant factor affecting the long-term metallic ureteral stent patency period. There were no major complications.ConclusionThe Resonance Metallic Ureteral Stent was effective and safe for patients with malignant ureteral obstruction. A normal serum creatinine level one week after placement of a polymer ureteral stent may predict a longer patency period of metallic ureteral stents in patients with malignant ureteral obstruction.