Metallic ureteral stents in malignant ureteral obstruction: short-term results and radiological features predicting stent failure in patients with non-urological malignancies

Analysis of Ureteral Tumour Stents for Malignant Ureteral Obstruction: Towards Reshaping an Optimal Stent

Introduction

Ureteral obstruction hinders the management of malignant diseases. Adequate stent placement does not necessarily guarantee renal decompression. The stent stiffness may play a major role to maintain patency. We carried out the present study in order to evaluate drainage efficiency by using stents with distinctive degrees of stiffness and to identify the physical factors that could prevent obstruction of the stent in patients with malignant ureteral obstruction (MUO).

Materials and Methods

We performed an analysis of 150 patients with MUO drainage at a single institution from June 2009 to June 2019. A progressive choice of stents was shaped to overcome each failure by focusing on the criterion of increasingly stiff stents.

Results

During the study period, 556 ureteral stent procedures (USP) were analysed separately. The stent failure with obstruction occurred in 23.0% (128/556) of USP at a mean of 4.4±3.6 months and depended on the type of stent. Stent failure occurred in 34.2% (70/205) of Vortek^® stents, in 42.9% (15/35) of Urosoft stents, in 15.4% (39/254) of Superglide or ureteral catheters and in 6.5% (4/62) of tandem stents. No significant differences were found between Vortek^® and Urosoft stents regarding stent failures, but there were significant differences between Superglide or Tandem stents and Vortek^® or Urosoft stents (p<10⁻⁷). The study demonstrated that ureteral stent obstruction significantly decreased with a larger lumen or a stiffer stent (p<10⁻⁷).

Conclusion

In the present study, Superglide and tandem stents were the best stents against stent failure, and the lumen and the stiffness of the stent have been shown to be critical factors in controlling patency. The results suggest that the lumen seems more important than the stiffness, and the stiffness would be the only means of keeping the lumen intact. Future stents for MUO should integrate the importance of the lumen of the stent.

Clinical factors predicting ureteral stent failure in patients with external ureteral compression

Double-J stent (DJ) placement is usually the treatment of choice for relieving external compression of the ureter. However, in some cases DJ function may become impaired and a percutaneous nephrostomy (PCN) may be required. Previous studies have reported different predictive factors for choosing PCN or DJ insertion as the initial treatment. In this study, we analyzed the risk factors for DJ failure in patients with external ureteral compression. Our results showed that the patients with moderate and severe hydronephrosis (p-value = 0.0171 and 0.0249, respectively), preexisting pyuria (p-value = 0.0128), or lower ureter obstruction (p-value = 0.0305) were more prone to DJ laterality. Age was also an important predictor. Urologists should pay more attention to these patients and consider PCN as the initial treatment.

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

Background

Malignant 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.

Methods

This 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).

Results

The 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.

Conclusion

The 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.

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.

Flexible ureteroscopy lithotripsy combined with metallic ureteral stents for the treatment of patients with upper urinary tract calculi

Flexible ureteroscopy lithotripsy (FURS) is the most common treatment for patients with upper urinary tract calculi (diameter, <2 cm). The purpose of this prospective study was to assess the efficacy of FURS combined with metallic ureteral stents (MUS) for the treatment of upper urinary tract calculi. A total of 38 patients with upper urinary tract calculi were recruited in the present study, to compare the efficacy between FURS and FURS combined with MUS (FURS-MUS). The results demonstrated that FURS-MUS shortened operative time compared with FURS (35.2±1.2 vs. 57.4±1.7 min, respectively; P<0.01). Data also indicated that the clearance rate in FURS-MUS and FURS was decreased from 94.5 and 87.8%, respectively (P<0.05). FURS-MUS treatment decreased the duration of postoperative hospital stay compared with FURS (4.5±0.5 vs. 7.5±1.5 days, respectively; P<0.05). These data demonstrated that FURS-MUS significantly increased postoperative inflammation score compared with FURS (6.2±0.8 vs. 4.2±1.0, respectively; P<0.05). The complication rate and blood loss exhibited no significant difference between FURS-MUS and FURS (complication rate, 6.5% vs. 5.9%, respectively; blood loss, 4.2% vs. 4.6%, respectively). FURS-MUS significantly decreased inflammatory cytokines and risk of sepsis, and improved readmission rate, stone recurrence and progression-free survival compared with patients treated with FURS. In conclusion, these data suggested that FURS-MUS may be an efficient, minimally invasive and reproducible operation for patients with upper urinary tract calculi.

Risk factors in the prediction of long‐term patency of Resonance metallic ureteric stent in malignant ureteric obstruction

Objectives

Cancer is the second leading cause of death globally in 2018 with an estimated 9.6 million deaths. The costs of managing malignant ureteric obstruction (MUO) is a significant burden to any healthcare system. However, the management of MUO has long been a challenge for urologists. The standard options of percutaneous nephrostomy or polymer double J stents are fraught with problems. We report a large patient series with long‐term follow‐up in the use of Resonance metallic ureteric stents to relieve MUO, and identification of risk factors associated with stent failure.

Patients and methods

All patients with MUO who were arranged to have Resonance metallic ureteric stent insertion at two university hospitals were included in this cohort study, starting from June 2011 to July 2016. Data were retrieved retrospectively. The primary outcome was the total duration of stent patency before stent failure due to malignant disease progression. Stent failure was defined as ureteric obstruction identified on imaging (functional radioisotope scan or antegrade pyelogram), acute renal failure resolved by subsequent percutaneous nephrostomy, or any other cause requiring stent removal prematurely. Secondary outcomes were identification of factors associated with stent failure, grade III or above complication, and development of a risk‐adopted model to predict metallic ureteric stent patency rates in MUO patients. Median duration of functioning metallic ureteric stent was determined with Kaplan‐Meier survival curve.

Results

A total of 124 renal units in 95 patients with MUO were eligible for the study, with a median follow‐up period of 22.9 months. About 106 (85.5%) renal units had successful metallic stent insertion, of whom 41 (33.1%) renal units ultimately progressed to ureteric obstruction despite the metallic stents, and required subsequent insertion of nephrostomies. Median duration of functioning metallic ureteric stents was 25 months. Female gender (HR 3.0, 95% CI: 1.3‐7.2, P = .014) and suspicious bladder lesion (HR 2.9, 95% CI: 1.4‐6.2, P = .005) were independent risk factors for stent failure, respectively. Stratifying patients into low (0 risk factor), intermediate (1 risk factor), and high (2 risk factors) risk groups, we found that this could predict the duration of stent patency in MUO with the metallic stents. (Low risk: 30.3 months vs intermediate group: 17.8 months vs high risk: 4.9 months, P < .001).

Conclusion

Resonance metallic ureteral stents are able provide a median of 25 months of ureteric drainage in patients with MUO. Determining whether a patient has one or both risks factors (female gender and bladder lesion) will allow one to estimate the duration of metallic stent patency, which in turn may aid in determining cost‐effectiveness in individual patients.

Application of metallic ureteral stents in gynecological malignancies: a literature review

Ureteral obstruction caused by extrinsic compression from advanced pelvic malignancies are not unusual in urology, with gynecological origin being the most common. As minimally invasive treatments for malignant ureteral obstruction (MUO), metallic ureteral stents have been promoted to provide long-lasting urinary patency and overcome the inherent limits of traditional double-J stents. In this review, we demonstrated three types of frequently used metal stents, including coiled stents, self-expendable stents and thermo-expendable stents. The Wallstent presented discrepant patency rates ranging from 6% to 100%, along with a high occlusion rate. The Memokath 051 stent showed satisfactory patency rates, often > 90%, but also a specific higher migration rate. The Resonance stent provided overall promising results with published success rates ranging from 20% to 100%, which on the whole remains relatively high. The long-term effectiveness rendered metal stents as viable options for managing MUO.

Treatment outcomes of ureteral stenting for malignant extrinsic ureteral obstruction: a comparison between polymeric and metallic stents

Purpose

To compare treatment outcomes, more specifically patency rate, of polymeric and metallic stents for malignant ureteral obstruction.

Patients and methods

Between August 2007 and September 2017, we retrospectively analyzed the data of 92 patients (126 ureters) having a diagnosis of malignant extrinsic ureteral obstruction treated with indwelling ureteral stents (polymeric and full-length metallic stents). Of these patients, 35 (54 ureters) were treated with polymeric stents and 57 (72 ureters) with a Resonance® metallic stent. The observation period was censored to 1 year. Survival rate in cases of malignant ureteral obstruction was calculated, and the relationship between the causes of ureteral obstruction, the stent type, and the patency rate was evaluated.

Results

The median observation period was 145 days, with a median survival time of 258 days. The stent patency rate was 70.9% at 1 year, regardless of stent type. Stent occlusion was observed in 20 patients (33 ureters). According to stent type, occlusion of the polymeric and metallic stents was identified in 12 (22%) and 8 (11%) cases, respectively. The clinical features associated with stent failure were assessed. In univariate analysis, the patency rate was significantly better for the metallic stent than for the polymeric stent (1-year patency rate; 78.4%, 61.1%, respectively, HR, 2.15; 95% CI, 1.07-4.33; p=0.031). However, the patency rate among patients with abdominal dissemination, lymph node metastasis, and direct compression by tumor was not significantly different.

Conclusion

Indwelling ureteral stents, particularly metallic stents, are effective for the treatment of malignant ureteral obstruction.

Initial Experience in the Use of Novel Auto-expandable Metal Ureteral Stent in the Treatment of Ureter Stenosis in Kidney Transplanted Patients

INTRODUCTION

Ureter stenosis in renal transplantation patients is a relatively frequent complication that negatively conditions graft evolution. The use of ureteral stents is a valid treatment alternative to the use of double-J catheters in patients for whom surgery is not contemplated or after surgical recurrence. We present our initial experience with five patients treated using this technique.

MATERIALS AND METHODS

We describe a total of five patients with ureteral stenosis after renal transplantation who were treated using ureteral stent model UVENTA (Taewoong Medical, Seoul, Korea) in our center. The median follow-up was 18 months (range, 4 to 38 months). We describe the clinical history of patients and previous treatments on ureteral stenosis. The technical procedure of placement is described. The clinical course is analyzed by measurement of renal function and imaging tests, as well as post-stent complications. Survival of the renal graft is evaluated.

RESULTS

The procedure could be completed in all patients without complications. The technique was effective in all patients, with correction of creatinine value and hydronephrosis during the renal ultrasound test. One patient suffered a urinary tract infection episode associated with the use of the ureteral stent. One patient suffered the loss of the renal graft secondary to the development of cryoglobulins. One hundred percent of the ureteral stents are functioning as of the writing of this article.

CONCLUSIONS

In renal transplantation patients with ureter stenosis, metallic stents are a useful technique with low morbidity and associated complications.

Application of resonance metallic stents for malignant ureteral obstruction

Purpose: To determine the effectiveness of the Resonance metallic stent in treating malignant ureteral obstruction (MUO) and clarify the risk factors that lead to stent failure. Material and methods: We retrospectively identified and analyzed the records of patients who had MUO and underwent placement of Resonance metallic stents from November 2014 to June 2017 in our hospital. Stent failure was defined as unexpected interventions including stent exchange, need of percutaneous nephrostomies (PCN) or ureterocutaneostomy. Results: A total of 22 stents were placed in 14 patients with MUO. The median follow-up was 145 days (4.8 months) and the maximum duration of stenting was 21.3 months. The technique success rate was 100%. Two patients experienced early postoperative increasing creatinine with oliguria but only one of them failed to achieve primary patency. The overall success rate was 90% (9/10). Conclusion: Resonance metallic stent is a safe and effective treatment for MUO and can maintain durable patency over 12 months. Preoperative urinary tract infection (UTI) and tumor invasion into the bladder are considered as risk factors of stent blockage and failure. Early postoperative elevated creatinine oliguria, suggestive with intrarenal and prerenal disease, should not be deemed to be stent failure.

Urological Management of Extramural Malignant Ureteric Obstruction: A Survey of Irish Urologists

Introduction

The absence of guidelines in the management of extramural malignant ureteric obstruction leads to confusion in decision making and in the interaction between urology and other clinical disciplines. In this study, we surveyed consultant urologists with the goal of achieving a better consensus on optimal management options.

Methods

A multiple choice survey was sent via the online survey tool "SurveyMonkey" to all consultant urologists practicing in the Republic of Ireland.

Results

There was a response rate of 57.5% (n = 23). Twenty-two (96%) consultants consider the use of percutaneous nephrostomy with placement of antegrade ureteric stent but only 22% (n = 5) would consider using a metallic stent. Eleven (48%) respondents favor retrograde stenting in the first instance with an equal proportion choosing an antegrade method. Nine (39%) consultants perform the initial stent change at 4-6 months, 8 (35%) at 2-4 months, and 1 at < 2 months and 6-10 months respectively. Total 59% (n = 13) of respondents felt that the duration of expected patient survival influenced their decision and agreement to stent with 42% (n = 8) saying this survival would need to be > 6 months and 82% (n = 18) were generally happy with the level of ongoing communication between urology and the primary service managing the patient.

Conclusion

There is a lack of consensus regarding the management of this challenging problem, particularly with regard to timing of first stent change and whether to initially use an antegrade or retrograde approach. This reflects the heterogeneous patient cohort and the important factors of life expectancy and patient co-morbidities.

Stents for malignant ureteral obstruction

Malignant ureteral obstruction can result in renal dysfunction or urosepsis and can limit the physician's ability to treat the underlying cancer. There are multiple methods to deal with ureteral obstruction including regular polymeric double J stents (DJS), tandem DJS, nephrostomy tubes, and then more specialized products such as solid metal stents (e.g., Resonance Stent, Cook Medical) and polyurethane stents reinforced with nickel-titanium (e.g., UVENTA stents, TaeWoong Medical). In patients who require long-term stenting, a nephrostomy tube could be transformed subcutaneously into an extra-anatomic stent that is then inserted into the bladder subcutaneously. We outline the most recent developments published since 2012 and report on identifiable risk factors that predict for failure of urinary drainage. These failures are typically a sign of cancer progression and the natural history of the disease rather than the individual type of drainage device. Factors that were identified to predict drainage failure included low serum albumin, bilateral hydronephrosis, elevated C-reactive protein, and the presence of pleural effusion. Head-to-head studies show that metal stents are superior to polymeric DJS in terms of maintaining patency. Discussions with the patient should take into consideration the frequency that exchanges will be needed, the need for externalized hardware (with nephrostomy tubes), or severe urinary symptoms in the case of internal DJS. This review will highlight the current state of diversions in the setting of malignant ureteral obstruction.