A new self-expanding, large-caliber ureteral stent: results of a multicenter experience

A new technique for the treatment of ureteric stricture after kidney transplantation

OBJECTIVE

To evaluate the safety and effectiveness of endoscopic treatments with Allium® metal ureteric stent (AMUS) for ureteric strictures after kidney transplantation (KT).

PATIENTS AND METHODS

In a prospective manner, we gathered clinical data from 68 patients who underwent endoscopic treatments with AMUS for ureteric strictures after KT between January 2019 and March 2022. The definition of surgical success was the unobstructed drainage of the AMUS, or in cases where there was AMUS migration, occlusion or encrustation and subsequently removed, there is no worsening of renal hydronephrosis in the patient during the follow-up period.

RESULTS

Based on the specific circumstances of the ureteric strictures, three distinct types of surgery were selected for treatment. The overall success rate of endoscopic treatments for ureteric strictures following KT was 90% (61/68) during a follow-up period of 1 year. Surgical complications included haematuria (18%), pain (10%), urinary tract infections (7.4%), and lower urinary tract symptoms (7.4%). The incidences of stent migration, occlusion, and encrustation were 10%, 2.9%, and 1.5%, respectively. Postoperatively, significant improvements were observed in various parameters. At 1 month after surgery, there was a notable decrease in blood creatinine levels (105.5 vs 90.4 mol/L), urea nitrogen levels (6.6 vs 5.4 mmol/L), and hydronephrosis volume (64.4 vs 43.9 mL). Additionally, the serum estimated glomerular filtration rate increased from 49.5 to 64.4 mL/min/1.73 m2. The follow-up results of patients at 1 year after surgery were similar to those observed at 1 month after surgery.

CONCLUSIONS

Systemic endoscopic treatments with AMUS were found to be safe and effective for ureteric strictures after KT with short-term follow-ups. This technique offers a novel option for the treatment of post-KT strictures.

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.

The Allium Ureteral Stent for the Treatment of Ureteral Complications Following Renal Transplantation-A Single-Center, Single-Surgeon Series

Ureteral complications such as urinary leak, ureteral necrosis or ureteral stenosis are common complications after renal transplantation with major short- and long-term issues, including graft impairment and graft loss. At present, there is no agreement on the optimal management of ureteral complications. The aim of the current study was to evaluate the safety and efficacy of the self-expanding, large-caliber Allium ureteral stent in patients with ureteral complications following renal transplantation. In this retrospective study, the electronic database of Charité University Hospital was screened for patients receiving the self-expandable Allium ureteral stent in the transplant ureter after kidney transplantation between January 2016 and March 2022. Descriptive statistics were used to describe the outcomes. There were six men and four women with a median age of 61 years (interquartile range, 55 to 68 years). Nine out of 10 patients had ureteric stenosis, which was diagnosed at a median of two years (interquartile range 10 months to 9 years) following renal transplantation. The median operating time was 49 min (interquartile range, 30 to 60 min). Endoscopic Allium stent placement was successful in all patients with ureteric stenosis. The median length of stay in the hospital was four days (interquartile range 2 to 7 days). Only one patient (#5) had a postoperative grade IIIb Clavien-Dindo complication. Patients had follow-ups every 3 months with ultrasound and serum creatinine. Dislocation of the Allium stent was seen in four patients; all occurred within three months. Ultimately, three patients required ureteric re-implantation, two of which had early dislocation of the stent. Six patients are managed with a permanent Allium stent. The median dwell time was 11 months (interquartile range 3 to 20 months) and maximum dwell time was 23 months. The overall success rate was 60% (6 out of 10). According to our data, the Allium stent represents a safe and minimally invasive option with a success rate of 60%. It might, therefore, represent an alternative to DJ stents, nephrostomies or immediate re-implantation. As all dislocations occurred within three months, frequent early postoperative follow-up is required.

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.

Allium Ureteral Stent as a Treatment for Ureteral Stricture: Results and Concerns

INTRODUCTION

Ureteral strictures could be a chronic illness that leads to severe side effects and poor quality of life. A treatment with an Allium ureteral stent (URS), a self-expanding, large-caliber URS, was implemented in our department for ureteral stricture. Our study aim was to report the long-term results, including success rate, complications, and adverse effects.

METHODS

We retrospectively collected data on all patients who were treated with an Allium URS in our department between January 2017 and January 2021. Demographic, clinical, radiological, and perioperative parameters were retrieved and analyzed. The primary outcome was stricture resolution rates following stent removal.

RESULTS

Our cohort included 17 patients, 9 men and 8 women. The etiology of ureteral strictures was urolithiasis in 76.5% and pelvic procedure injury in 17.6%. The overall success rate was 35.29% in an average follow-up of 10.42 ± 2.39 months after stent removal. A higher failure rate was observed in the urolithiasis etiology group (90% vs. 66.7%, p = 0.38). The mean indwelling time of the Allium stent was 14.29 ± 1.29 months.

CONCLUSIONS

Although an Allium URS could be considered as a feasible and attractive treatment of ureteral strictures, due to its minimal invasiveness, the success rate of this treatment is relatively low. Therefore, this option should be carefully considered and should be discouraged in young and fit patients and reserved for older unfit patients who are unwilling to undergo surgical repair of ureteral strictures.

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.

Stenting of Malignant Urinary Tract Obstructions in Humans and Companion Animals

Urine retention secondary to neoplastic obstructions of the upper and lower urinary tracts is a life-threatening condition in both humans and companion animals. Stents can be placed to temporarily or permanently open obstructed urinary tract lumens and are often able to be placed using minimally invasive techniques with guidance via ultrasonography or fluoroscopy. The literature for these techniques is vast for humans and growing for companion animals. The below review provides a discussion of the principles of stenting and types of ureteral and urethral stents, as well as the techniques for placing these stents in humans and companion animals.

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

BACKGROUND

The 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.

METHODS

We 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.

RESULTS

A 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).

CONCLUSIONS

URS 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

BACKGROUND

To assess the efficacy and safety of self-expanding metal ureteral stent for the stricture following surgery and/or radiation for malignancy.

METHODS

We 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.

RESULTS

The 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.

CONCLUSIONS

The 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.

Step-by-step technique for the endoscopic treatment of ureteric stricture

OBJECTIVE

To outline our step-by-step technique for the endoscopic treatment of ureteric stricture.

MATERIALS AND METHODS

Between January 2019 and June 2020, 25 patients with ureteric strictures underwent ureteric bypass and were included in this study. The ureteric bypass surgery included three key steps. First, holmium laser endoureterotomy was used to establish a small channel. Then, balloon dilatation was performed to create a large channel. Finally, an Allium stent was inserted.

RESULTS

Over a median follow-up time of 12 months, the success rate of ureteric bypass surgery was 92.0% (23/25). The median operating time was 78 min. The incidence of pain was 16% (4/25), and the incidence of fever was 4.0% (1/25). The preoperative hydronephrosis volume and urea nitrogen levels decreased significantly after surgery.

CONCLUSIONS

We performed ureteric bypass for patients with ureteric strictures. This technique was found to be safe and effective over a short follow-up time. For patients who are not suitable for surgical reconstruction, the ureteric bypass technique is a good choice.

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

PURPOSE

Patients with chronic ureteric obstruction (CUO) are traditionally managed with polymer stents/nephrostomy. However, these are prone to failure and require regular exchange. This study evaluates efficacy of Allium® URS, Memokath™-051 and Resonance® metallic ureteric stents in managing patients with CUO.

METHOD

Following institutional approval, operating theatre records were reviewed to identify patients with CUO managed with either Allium® URS, Memokath™-051 or Resonance® metallic ureteric stents (September 2015/July 2020). Baseline patient variables (age, gender, underlying aetiology, ASA) and stricture characteristics (length, level, continuity) were extracted. Intra- and post-operative clinical and radiological assessments at 6 weeks, 3 months and then every 6 months, as well as any emergency attendances, were reviewed. The primary outcome was duration of functional stent survival. Secondary outcomes included intra-operative placement success and, as anestimate of renal function, mean serum creatinine over time.

RESULTS

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). Kaplan-Meier estimates demonstrated that Resonance® provided superior functional stent survival. Overall median actual functional stent follow-up was 11.4 months for Allium® URS, 5.5 months for Memokath™-051 and 11.7 months for Resonance®. 47.8% of Allium® URS (11/23), 64.6% of Memokath™-051 (31/48) and 19% of Resonance® SIEs (11/58) failed. No Resonance® SIEs for benign indication ended in failure. Intra-operative placement success was high (Allium® URS: 95.7%; Memokath™-051 and Resonance®: both 100%). In the first year following SIE, 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. In this cohort, Resonance® provided superior functional stent survival. Prospective large-scale comparisons with long-term follow-up are needed to help inform stent choice dependant on individual patient and stricture characteristics.

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

Background

Refractory non-malignant ureterostenosis is challenging to treat. The experience to treat the stenosis primarily cause by retroperitoneal fibrosis with the Resonance and Allium metallic stent is still limited. We aim to evaluate the efficacy and safety of these two stents and provide alternative treatment options.

Methods

A retrospective study was conducted for patients with non-malignant ureterostenosis and treated with the Resonance and Allium stents from March 2011 to September 2020 in our department. The efficacy was evaluated by the change of serum creatinine, glomerular filtration rate (GFR), the proportion of GFR of the affected side and hydronephrosis grade. The safety was evaluated by postoperative presence of moderate or severe overactive bladder (OAB), recurrent urinary infection, pain, stent displacement, encrustation and re-obstruction.

Results

33 patients were eligible for the study, including 18 cases treated by the Resonance stents and 15 patients treated by the Allium stents. The patients of two groups had similar age and gender proportion. The cause of ureterostenosis was mainly retroperitoneal fibrosis in both groups but the Resonance group had more idiopathic cases. Follow-up time was significantly longer in the Resonance group than the Allium group (36.2 ± 24.0 vs 9.4 ± 5.0 months, p < 0.001). Both groups showed improvement or maintenance of serum creatinine level, GFR, the GFR proportion of the affected side and hydronephrosis grade after treatment. The Resonance group presented significant higher incidence of moderate or severe OAB, recurrent urinary infection and pain, while the Allium group showed significant more cases of re-obstruction.

Conclusion

Both the Resonance and Allium stent can relieve the non-malignant refractory ureterostenosis effectively. The Resonance stent may cause more irritable symptoms while the Allium stent may have a higher rate of re-obstruction. The long term efficacy and safety of the Allium stent in treating non-malignant refractory ureterostenosis requires further study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-021-00815-6.

A systematic review of long-duration stents for ureteral stricture: which one to choose?

OBJECTIVE

To define which long-term stent would work best in malignant ureteral obstruction (MUO) and benign ureteral obstruction (BUO), focusing on their mechanisms of action, price and insertion approach.

METHODS

A systematic review was developed using the MEDLINE and Scopus databases and in accordance with the PRISMA checklist. There were no language restrictions for the search. Studies describing the use of metallic ureteric stents for MUO and for BUO in humans were included.

RESULTS

We analyzed five types of metallic stents (35 papers) and also the experience with the tumor and extra-anatomical stents. The Resonance, Memokath and Allium ureteral stents were found to be useful in BUO and MUO. The Uventa stent performed well in chronic ureteral obstruction. The Detour bypass stent was a recommended option in those patients who had complete obstruction of the ureter and were unfit for reconstructive surgery. There was no difference with regard to the insertion technique and both antegrade and retrograde approaches were equally successful. Although tumor stents showed a good performance, there were very few published studies on it.

CONCLUSION

Metallic stents are a suitable option for MUO and BUO. When compared to standard double J stents, although they are relatively high priced, they show a financial benefit in the long-term. The Detour bypass stent seems to be an effective alternative for complete ureteral obstruction or patients unfit for surgery. Further prospective randomized studies should be done on the effectiveness of tumor stents versus metallic stents.

[Initial clinical experience and follow-up outcomes of treatment for ureteroileal anastomotic stricture with Allium coated metal ureteral stent]

OBJECTIVE

To summarize the initial clinical experience and follow-up results of the treatment for ureteroileal anastomotic stricture after radical cystectomy with Allium coated metal ureteral stent.

METHODS

From September 2018 to September 2019, 8 patients with ureteroileal anastomotic stricture after radical cystectomy underwent Allium ureteral stent insertion in Peking University People's Hospital and People's Hospital of Daxing District. The preoperative renal pelvis width under ultrasound was collected to evaluate the postoperative hydronephrosis, creatinine and urea nitrogen (BUN) before and after surgery, perioperative infection, and stent-related complications. The serum creatinine and BUN, renal pelvis width under ultrasound, urography and abdominal plain film (KUB) were reviewed at the end of 1, 3, and 6 months and annually postoperatively to observe the stent position and morphology. The long-term stent patency rate, complication rate, renal function and hydronephrosis were followed up and analyzed. The t-test or rank-sum test was used to compare the measurement data of the matched sample from the preoperative to the last follow-up.

RESULTS

In the study, 6 cases (7 sides) were ureteral ileal conduit stricture, and 2 cases (3 sides) ureteral orthotopic neobladder stricture. Before surgery, 5 patients underwent long-term indwelling of a single J ureteral stent, with an average indwelling time of (20.6±8.8) months and an average replacement frequency of (3.6±1.3) months/time. The mean width of renal pelvis was (26.5±9.1) mm on preoperative renal ultrasonography. Among them, 6 patients were successfully indwelled with Allium coated metal ureteral stent by retrograde approach, and 2 patients by combination of double-endoscopy and ante-retrograde approach. No surgery-related complications during perioperative period were observed. The mean follow-up period was 9.8 months and Allium stent and ureter remained unobstructed in all the patients at the last follow-up without replacement or removal. Compared with preoperative data, the mean width of renal pelvis and mean blood urea nitrogen (BUN) in the last follow-up period were significantly reduced [(26.5±9.1) mm vs. (13.4±2.5) mm, P=0.008; (11.6±2.3) mmol/L vs. (10.2±2.2) mmol/L, P=0.017], however, there were no significant differences in the average serum creatinine or hemoglobin (P>0.05). Ureteroileal anastomotic re-stricture and other stent-related complications were not observed in all the patients by antegrade urography.

CONCLUSION

Allium coated metal ureteral stent could be used for the treatment for ureteroileal anastomotic stricture, which could maintain relatively long-term patency rate and protect renal function. The indwelling time was longer and it could improve quality of life of patients.

Management and treatment options when facing malignant ureteral obstruction

Malignant ureteral obstruction is an unfortunate finding that can be caused by a wide-ranging number of malignancies with a prognosis of limited survival. Given its presentation and progression, it can be refractory to treatment by traditional single polymeric ureteral stents. With a higher failure rate than causes of benign ureteral obstruction, a number of other options are available for initial management, as well as in cases of first-line therapy failure, including tandem stents, metallic stents, percutaneous nephrostomies and extra-anatomic stents. We reviewed the literature and carried out a PubMed search including the following keywords and phrases: "malignant ureteral obstruction," "tandem ureteral stents," "metallic ureteral stents," "resonance stent," "metal mesh ureteral stents" and "extra-anatomic stents." The vast majority of studies were small and retrospective, with a large number of studies related to metallic stents. Given the heterogenous patient population and diversity of practice, it is difficult to truly assess the efficacy of each method. As there are no guidelines or major head-to-head prospective trials involving these techniques, it makes practicing up to the specific provider. However, this article attempts to provide a framework with which the urologist who is presented with malignant ureteral obstruction can plan in order to provide the individualized care on a case-by-case basis. What is clear is that prospective, randomized clinical trials are necessary to help bring evidence-based medicine and guidelines for patients with malignant ureteral obstruction.

The Ureter in the Kidney Transplant Setting: Ureteroneocystostomy Surgical Options, Double-J Stent Considerations and Management of Related Complications

Purpose of Review

In the setting of kidney transplantation, the ureter is a common source for complications. As a result, prevention of ureteral complications and their management is of crucial importance. In this context, the purpose of this review is to summarize recent literature on the ureter in the kidney transplant setting with a special focus on new findings. We conducted a PubMed and Medline search over the last 10 years to identify all new publications related to ureteroneoimplantations, stents and management of complications in the kidney transplant setting.

Recent Findings

Performance of the “Lich-Gregoir” technique for ureteroneocystostomy seems to be favourable in regard to postoperative complications when compared with other methods described in the literature. Moreover, major urologic complications can be further reduced by ureteral stenting.

Summary

A new approach for management of ureteral strictures in renal transplants is presented. We discussed the usage of a ureteral stent covered with a biostable polymer aiming to prevent tissue ingrowth into the lumen as a new option for management of ureteral stricture in the kidney transplant setting.

Metallic Ureteric Stents in Malignant Ureteric Obstruction: A Systematic Review

The effectiveness of metallic stents in the management of malignant ureteric obstruction is unclear. This systematic review evaluates the use of 4 commercially available metallic stents (Resonance, Memokath 051, Uventa, and Allium URS). Twenty-one studies met eligibility criteria. Overall success rates ranged from 88% for the Allium stent to 65% for Memokath 051. Resonance demonstrated the lowest migration rate (1%). Uventa had the lowest obstruction rate (6%). Metallic ureteric stents offer a viable alternative in the management of malignant ureteric obstruction. Further high quality studies are required to assess cost effectiveness and refine specific indications based on etiology and level of the ureteric obstruction.

Comparison of single and tandem ureteral stenting for malignant ureteral obstruction: a prospective study of 104 patients

OBJECTIVES

The aim of this study was to compare single and tandem ureteral stenting in the management of malignant ureteral obstruction (MUO).

METHODS

Our hospital's institutional review board approved this prospective study. Between November 2014 and June 2017, single ureteral stenting was performed in 56 patients (94 renal units) and tandem ureteral stenting in 48 patients (63 renal units) for MUO. A comparative analysis of the technical success rate, patient survival, stent patency, and complications was performed.

RESULTS

Similar demographic data were observed in patients receiving either single or tandem ureteral stenting. The technical success rate was 93.6% (88/94) for single ureteral stenting and 95.2% (60/63) for tandem ureteral stenting. There was no difference in overall survival between patients receiving single or tandem ureteral stenting (p = 0.41), but the duration of stent patency in tandem ureteral stenting was significantly longer (p = 0.022). The mean patency time was 176.7 ± 21.3 days for single ureteral stenting, and 214.7 ± 21.0 days for tandem ureteral stenting. The complications of ureteral stenting were urinary tract infection (n = 18), lower urinary tract symptoms (n = 5), haematuria (n = 3), and stent migration (n = 1).

CONCLUSIONS

Tandem ureteral stenting is a safe and feasible treatment for MUO, and had better efficacy compared to single ureteral stenting.

KEY POINTS

• Ureteral stenting is an established treatment for the management of malignant ureteral obstruction (MUO) • Prospective single-centre study showed that tandem ureteral stenting is a safe and feasible treatment for MUO • Tandem ureteral stenting provides longer stent patency compared to single ureteral stenting in patient with MUO.

Allium Stents: A Novel Solution for the Management of Upper and Lower Urinary Tract Strictures

Stents are widely use in endoscopic urological procedures. One of the most important indications is the treatment of urinary tract strictures. Allium™ Medical has introduced several types of stents for the treatment of different types of urinary tract strictures, based on anatomic location. All the stents are made of nitinol and coated with a co-polymer that reduces encrustations. These stents are self-expandable and have a large caliber and a high radial force. They have different shapes, designed especially for the treatment of each type of stricture. One of the most important features of Allium-manufactured stents is the ease of removal, due to their special unraveling feature. The company has introduced the Bulbar Urethral Stent (BUS) for treatment of bulbar urethral strictures; a rounded stent available in different lengths. Initial data on 64 patients with bulbar urethral stricture treated with the BUS showed a significant improvement in symptoms, with minimal complications and few adverse events. For treatment of prostate obstruction in patients unfit for surgery or unwilling to undergo a classical prostatic surgery, the Triangular Prostatic Stent (TPS) was introduced, which has a triangular shape that fits in the prostatic urethra. Its body has a high radial force attached to an anchor (which prevents migration) through a trans-sphincteric wire (which reduces incontinence rate). Initial data on 51 patients showed significant improvement in symptoms and in urinary peak flow rate, with a relatively small number of complications. The Round Posterior Stent (RPS) was designed for treatment of post radical prostatectomy bladder neck contracture. This short, round stent has an anchor, which is placed in the bladder neck. This stent being relatively new, the clinical data are still limited. Ureteral strictures can be treated with the Ureteral Stent (URS), which is round-shaped, available in different lengths, and has an anchor option (for very distal or very proximal strictures). We have previously published data on 107 URSs inserted in patients with ureteral stricture due to several etiologies, including patients who failed previous treatment. All patients were asymptomatic for a long period of follow-up after stent removal, with only one case of re-stenosis. In this paper, we review the urological "covered" stents produced by Allium Medical with the relevant clinical data available at the present time.

The effectiveness of ureteric metal stents in malignant ureteric obstructions: A systematic review

Objective

To review the literature on the effectiveness, safety and long-term patency of ureteric metal mesh stents (MSs), as a variety of MSs have been used for managing malignant ureteric obstruction over the last three decades.

Materials and methods

A systematic review using the search string; Ureter∗ AND (stent OR endoprosthesis) AND metal∗ was conducted on PubMed, Scopus, Web of science and Cochrane Library online databases in May 2016. Prospective, retrospective, and comparative studies including MSs were included. The primary endpoint was the patency rate and the secondary endpoint was complications.

Results

In all, 324 publications were screened and 31 articles were included in the systematic review; 21 prospective and 10 retrospective studies. These studies reported the effectiveness of specific MSs in population studies, in comparative studies among different MSs, as well as among MSs and JJ stents. It should be noted that all comparative studies were retrospective.

Conclusion

The experiences with vascular MSs, such as the Wallstent™ (Boston Scientific/Microvasive, Natick, MA, USA), were related to high occlusion rates, due to endoluminal hyperplasia, and long-term disappointing patency. The use of covered MSs designed for the vascular system was also unfavourable. The Memokath 051™ (PNN Medical A/S, Kvistgaard, Denmark) had better patency rates, but also higher migration rates. The long-term results were acceptable and rendered the Memokath 051 as a viable option for the management of malignant ureteric obstruction. The Uventa™ (Taewoong Medical, Seoul, Korea) and Allium™ (Allium Medical Solutions Ltd, Caesarea, Israel) MSs, specifically designed for ureteric placement, provided promising results. Nevertheless, the wide acceptance of these MSs would require well-designed clinical studies and long-term follow-up.

Allium stent for the treatment of a malignant ureteral stenosis: A paradigmatic case

OBJECTIVE

The aim of this study was to present a paradigmatic case where the new-generation Allium URS stent was the optimal choice to treat a malignant ureteral stenosis.

METHODS

We describe in detail all the steps of our surgery, performed on a 69-year-old patient with left hydronephrosis caused by lumbo-aortic nodal metastases compressing the ureter. The patient was intolerant to double-J stent due to strong irritative urinary symptoms. Allium URS stent was positioned under fluoroscopy in replacement of pre-existing double-J stent.

RESULTS

Our approach was successful and irritative urinary symptoms disappeared. At 6 months, the Allium URS was correctly positioned and no hydronephrosis was detected on ultrasound. The stent can be left in place for a maximum of 3 years.

CONCLUSIONS

In complicated scenarios of chronic ureteral stenosis, the new-generation Allium URS can be an interesting option to treat the obstruction while sparing the patient the irritative urinary symptoms and periodic replacements typical of a double-J stent.

[The Allium ureteral stent in the management of ureteral stenoses, a retrospective, multicenter study]

OBJECTIVE

To evaluate the performance of the Allium ureteral stent in the management of patients initially treated with double J stents for the long-term treatment of stenoses.

MATERIALS AND METHODS

We performed a retrospective multicenter study involving 36 patients who received 37 Allium ureteral stents (metallic 24 Fr) between September 2011 and January 2015 in one of three French teaching hospital centers. The mean age of the patients was 63.8 years (min-max: 33-88 years) and most were women (70%). Of these patients, 5.6% had ureteral fistulae and 94.4% stenoses. Mean stenosis length was 4.15cm (min-max: 0.5-12cm). All analyses were two-tailed with an alpha risk of 0.05. Statistical significance was set at P<0.05. Results were expressed as hazard ratios (HR) with 95% confidence intervals and P-values.

RESULTS

During the follow-up period, 37% of the stents were removed due to migration (complication occurring in 18.9% of the studied population), infection (10.8%) or intolerance (8.1%). The other stents were removed after 1 year. Clinical effectiveness, defined as a lack of stenosis or fistula recurrence, was 52.8% after a mean follow-up of 7.1 months.

CONCLUSION

Clinically effective in more than 50% of cases, the Allium ureteral stent appears to be an alternative to indwelling double J stents.

LEVEL OF EVIDENCE

4.

Endoureteral Management of Renal Graft Ureteral Stenosis by the Use of Long-Term Metal Stent: An Appealing Treatment Option

Background: Ureteral stenosis is part of the common complications of renal graft reported in 3% to 7% of cases. Multiple treatments have been introduced regarding length and position of the stenosis. Metal stents for urologic purpose were created in 1998. Double percutaneous antegrade and transurethral retrograde access to a ureteral stenosis to a long-term metal stent procedure has been rarely described. Case Presentation: Here, we present a case of a ureteral stricture in a double ipsilateral kidney graft with a common ureter. A 67-year-old patient presented with obstructive nephritis associated with acute renal failure 6 years after a double renal graft with a uretero-ureteral end-to-side anastomosis. Abdominal CT scan showed double pelvic dilation. The patient underwent double percutaneous nephrostomies and antegrade pyelogram showed both renal pelvic and ureter dilations caused by a severe chronic ureteral stenosis at junction into the bladder. A Double-J ureteric stent was then inserted retrogradely over a guidewire as first-line treatment. Due to recurrent urinary tract infections (UTIs), removal and replacement of Double-J stents were carried out by placing a thermoexpandable metal stent Memokath^® 051 (Bard, Pnn Medical) through the common ureter by a double antegrade and retrograde approach. Treatment was effective with a good renal function maintained after a 3-year follow-up without UTIs. Conclusion: Double antegrade and retrograde access to a long-term metal stent treatment can be seen as an alternative treatment to either endoscopy or open surgery. Further studies should be continued using larger series.

Ureteral strictures revisited…trying to see the light at the end of the tunnel: a comprehensive review

A ureteral stricture is a rather rare urological event defined as a narrowing of the ureter causing a functional obstruction and renal failure, if left untreated. The aim of this review article is to summarize and discuss current knowledge on the incidence, pathogenesis, management, and follow up of proximal, mid, and distal ureteral strictures.

Metallic stents in the management of ureteric strictures

Management of ureteric strictures is a challenging task. Subtle presentation, silent progression and complex aetiology may delay diagnosis. A wide range of available treatment options combined with the lack of adequate randomised trials has led to the introduction of personal bias in the management of this difficult group of patients. Metallic ureteric stents offer an alternative to the conventional treatment modalities. A review of the currently available metallic stents and their role in the long-term management of ureteric strictures is presented. Materials used in the manufacture of indwelling urological devices are evolving all the time. Improved endo-urological techniques combined with new devices made from better compounds will continue to improve patient experience.

Current status of minimally invasive endoscopic management of ureteric strictures

Endourological techniques are used more often nowadays in the treatment of ureteric strictures of various etiologies. Advances in technology have provided new tools to the armamentarium of the endoscopic urological surgeon. Numerous studies exist that investigate the efficiency and safety of each of the therapeutic modalities available. In this review, we attempt to demonstrate the available and contemporary evidence supporting each minimally invasive modality in the management of ureteric strictures.