Palliative care of malignant ureteral obstruction with polytetrafluoroethylene membrane-covered self-expandable metallic stents: initial experience

Unraveling the Complexities of Uretero-Enteric Strictures: A Modern Review

PURPOSE OF REVIEW

The purpose of this review article is to provide a contemporary overview of benign uretero-enteric anastomotic stricture (UAS) management and outcomes.

RECENT FINDINGS

In this article, we will review the most recent studies investigating UAS and evaluate etiology, potential risk factors, presentation, diagnosis, and management options, along with personal insight gained from our experience with managing this challenging reconstructive complication. Benign UAS is a relatively common long-term complication of intestinal urinary diversion, affecting approximately 1 in 10 patients. It is thought to be caused by ureteral tissue ischemia and fibrosis at the anastomotic site. Risk factors appear to include any that increase the likelihood of leak or ischemia; it is not clear if anastomotic approach impacts risk for stricture as well. Management options are varied and include endourologic, open, and robotic approaches. Endoscopic approaches may be less morbid but are considerably less effective than reconstruction performed after a period of ureteral rest.

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.

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.

Self-Expandable Covered Metallic Stent (UVENTA) to Treat a Ureteral Stricture After Renal Transplant: A Case Report

We present the use of a self-expandable covered metallic stent (UVENTA; TaeWoong Medical, Gyeonggi-do, South Korea) to treat a ureteral stricture after kidney transplant. In this report, we describe the procedure and short-term outcomes of a patient with a recurrent distal stricture who did not respond to percutaneous balloon dilation. We decided to place this temporary stent as an alternative to complex surgery. The aim of the procedure was to get a chronic dilation of the stricture up to 7 mm to stabilize the fibrotic tissue. The procedure was easily and quickly performed by an antegrade and retrograde combined approach. The postoperative course was uneventful. The stent was left in situ for 7 months. No complications were noted, and the renal function remained stable. The stent was easily removed, and 5 months later there were no signs of recurrence. The UVENTA device was shown to be an easy, safe, and effective minimally invasive treatment for ureteral stricture in renal transplant. Proper permanence time and long-term results need to be explored.

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.

A Prospective Randomized Comparison of a Covered Metallic Ureteral Stent and a Double-J Stent for Malignant Ureteral Obstruction

Objective

To compare the safety and efficacy between a covered metallic ureteral stent (CMS) and a double-J ureteral stent (DJS) for the treatment of a malignant ureteral obstruction (MUO).

Materials and Methods

Nineteen patients (seven men and 12 women; mean age, 53.4 years) were randomly assigned to the CMS (n = 10) or DJS (n = 9) group. The following were compared between the two groups: technical success, i.e., successful stent placement into desired locations; stent malfunction; stent patency, i.e., no obstruction and no additional intervention; complications; and patient survival.

Results

The technical success rate was 100% in all 10 and 12 ureteral units in the CMS and DJS groups, respectively. During the mean follow-up period of 253.9 days (range, 63–655 days), stent malfunction was observed in 40.0% (4/10) and 66.7% (8/12) in the CMS and DJS groups, respectively. In the per-ureteral analysis, the median patency time was 239.0 days and 80.0 days in the CMS and DJS groups, respectively. The CMS group yielded higher patency rates compared with the DJS group at three months (90% vs. 35%) and at six months (57% vs. 21%). The overall patency rates were significantly higher in the CMS group (p = 0.041). Complications included the migration of two metallic stents in one patient in the CMS group, which were removed in a retrograde manner. The two patient groups did not differ significantly regarding their overall survival rates (p = 0.286).

Conclusion

Covered metallic ureteral stent may be effective for MUO.

Endoscopic Management of Ureteral Strictures: an Update

PURPOSE OF REVIEW

This review focuses on the role of endoscopic treatment of ureteral stricture disease (USD) in the era of minimally invasive surgery.

RECENT FINDINGS

There is a relative paucity of recent literature regarding the endoscopic treatment of USD. Laser endopyelotomy and balloon dilation are associated with good outcomes in treatment-naïve patients with short (< 2 cm), non-ischemic, benign ureteral strictures with a functional renal unit. If stricture recurs, repetitive dilation and laser endopyleotomy is not recommended, as success rates are low in this scenario. Patients with low-complexity ureteroenteric strictures and transplant strictures may benefit from endoscopic treatment options, although formal reconstruction offers higher rates of success. Formal ureteral reconstruction remains the gold-standard treatment for ureteral stricture disease as it is associated with higher rates of complete resolution. However, in carefully selected patients, endoscopic treatment modalities provide a low-cost, low-morbidity alternative.

Risk Factors for Primary Failure of Metallic Ureteral Stents: Experience from a Tertiary Center

Introduction: We provide primary patency rate of metallic ureteral stents in cancer patients and investigate the factors affecting primary patency. Methods: All cancer patients who had received metallic stents for malignant ureteral obstruction between July 2009 and November 2012 in our institute were included. No patients were excluded. Patient profiles, imaging studies, and laboratory data were collected. Patient profiles included age, gender, body height, body weight, body mass index, cancer types, treatment for cancer, response to cancer treatment, methods of stent insertion, and prior ordinary stents. Imaging studies included renal ultrasonography, antegrade pyelography, CT, and MRI. Laboratory data included urinalysis, urine culture, and serum creatinine. Complications were defined according to the Clavien-Dindo classification. Primary patency was defined as a complete resolution or downgrading of hydronephrosis shown by imaging studies or success in the removal of a preexisting nephrostomy tube; otherwise the procedure was considered a primary failure. The primary endpoint was the primary patency rate of the stents. The secondary endpoints were risk factors for primary stent failure. Results: A total of 124 stents were inserted into 96 patients with malignant ureteral obstruction. There were no grade 3/4 complications. The overall primary patency rate was 87.9% (109/124). In univariate analysis, antegrade insertion (OR = 24.15, p-value = 0.0086) and urinary tract cancer (OR = 4.18, p-value = 0.0164) were significantly associated with primary failure. Those with prior ordinary stents (OR = 0.20, p-value = 0.0158) or response to cancer treatment (OR = 0.25, p-value = 0.0228) were associated with stent patency. In multivariate analysis, antegrade insertion (OR = 22.04, p-value = 0.0041) and response to cancer treatment (OR = 0.15, p-value = 0.01081) remained significant factors. Conclusions: In this large cohort of cancer patients requiring urinary diversion to preserve renal function, several factors were associated with the success rate of metallic stents.

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.

Early Application of Permanent Metallic Mesh Stent in Substitution for Temporary Polymeric Ureteral Stent Reduces Unnecessary Ureteral Procedures in Patients With Malignant Ureteral Obstruction

OBJECTIVE

To identify risk factors for metal stent failure in patients who received polymeric double J (PDJ) ureteral stents for malignant ureteral obstructions (MUOs) and review our clinical experiences using a ureteral metallic stent.

PATIENTS AND METHODS

Patients who underwent metallic stent placement to replace a double J ureteral stent for nonurological MUO between January 2011 and February 2014 were included. The collected data included gender, age, laterality, cause of obstruction, PDJ ureteral stenting duration, immediate success of the metal stent, and additional procedures to relieve obstruction after metal stenting (eg, additional metal stenting or percutaneous nephrostomy (PCN) indwelling catheter placement). Cox regression tests were used for the statistical analyses.

RESULTS

In this analysis 40 ureteral units were included. There was no initial technical failure. However, 9 (22.5%) units required additional procedures due to de novo ureteral obstruction, including additional indwelling metal stents (7.5%), additional PDJ stenting (10%), or indwelling percutaneous nephrostomy (5%). Univariate and multivariate analyses revealed that the duration of previous PDJ ureteral stenting was an independent prognostic factor for predicting ureteral metal stent failure (hazard ratio = 1.063, 95% confidence interval = 1.004-1.125; P = .037).

CONCLUSION

Long-term indwelling of a PDJ ureteral stent increases the risk of additional management for de novo ureteral stricture after ureteral metal stent replacement for nonurological MUO. Our data suggest that careful patient selection and counseling for those at high risk are needed when metal stent replacement is considered for patients with long-term PDJ ureteral stents for MUO.

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.

Palliative management of malignant upper urinary tract obstruction

Malignancies of the genitourinary tract are diagnosed with increased frequency compared to the past. Currently prostate and bladder cancer account for the majority of urological malignancies. While for prostate cancer recent developments in the management of local and metastatic disease are likely to lead the majority of patients to either cure from the disease or to longer survival time, for bladder cancer advanced disease will unfortunately lead to death within months. However, the common clinical scenario in both prostate and bladder cancer includes, in high incidence, upper urinary tract obstruction in the advanced stages of these malignancies. This coupled with the fact that average life expectancy in the western world is increasing, will result in a significant patient population with either advanced, non-curable disease or with problems related to the received therapeutic surgical or medical interventions. There is no doubt that in both circumstances the room and role of palliation therapy is increasing. The care of patients with advanced urologic malignancies requires a multi-disciplinary effort from physicians of many specialties under the guiding role of the treating urologist. This review focuses on currently available palliative therapeutic options for upper urinary tract obstruction in the setting of patients with advanced malignancies of the urinary tract, as recently significant advancements have been witnessed in this field.

Comparison of efficacy and safety between a segmental thermo-expandable metal alloy spiral stent (Memokath 051) and a self-expandable covered metallic stent (UVENTA) in the management of ureteral obstructions

OBJECTIVE

To determine the efficacy and safety of the Memokath 051™ (PNN Medical, Glostrup, Denmark) and UVENTA™ (Taewoong Medical, Seoul, Korea) metal stents, we reviewed our experience with these two metallic ureteral stents for treating benign and malignant ureteral obstructions.

SUBJECTS AND METHODS

Twenty-seven patients who received treatment with metallic ureteral stents (Memokath 051, 10 patients; UVENTA, 17 patients) from November 2011 to May 2013 at our institution were identified and analyzed. We conducted a comparative analysis of the causes of obstruction, technical/clinical success rate, cause of failure, and complications.

RESULTS

No difference was observed between the two metallic stents for the causes of benign and malignant ureteral obstructions (P=.073). The Memokath 051 and the UVENTA were inserted successfully in all ureters using a retrograde technique. The mean follow-up was 13.6 months for Memokath 051 and 12 months for UVENTA (P=.244). The clinical success rate of the UVENTA was higher than that of Memokath 051 (82.4% versus 42.9%; P=.031). The causes of failure were obstruction by tumor progression (n=2) and stent migration (n=6) in cases that received Memokath 051 and stent migration (n=1) and obstruction by mucosal hyperplasia (n=2) in UVENTA. The complications caused by Memokath 051 were intermittent flank pain (n=1) and acute pyelonephritis (n=1), whereas those of UVENTA were intermittent flank pain (n=1), gross hematuria (n=1), and acute pyelonephritis (n=1).

CONCLUSIONS

The UVENTA achieved a higher clinical success rate than the Memokath 051. Our study demonstrated that the UVENTA is safe and effective in the management of benign and malignant ureteral obstruction. The complications were similar between the two metallic stents.

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.

Predicting factors for stent failure-free survival in patients with a malignant ureteral obstruction managed with ureteral stents

Purpose

To determine predictive factors for stent failure-free survival in patients treated with a retrograde ureteral stent for a malignant ureteral obstruction.

Materials and Methods

We retrospectively reviewed 71 patients who underwent insertion of a cystoscopic ureteral stent due to a malignant ureteral obstruction between May 2004 and June 2011. Performance status, type of cancer, hydronephrosis grade, location of the obstruction, presence of bladder invasion, C-reactive protein (CRP), serum albumin, and inflammation-based prognostic score (Glasgow prognostic score, GPS) were assessed using a Cox proportional regression hazard model as predicting factors for stent failure.

Results

A univariate analysis indicted that hypoalbuminemia (<3.5 g/dL; hazard ratio [HR], 2.43; 95% confidence interval [CI], 1.21 to 4.86; p=0.012), elevated CRP (≥1 mg/dL; HR, 4.79; 95% CI, 2.0 to 11.1; p=0.001), and presence of a distal ureter obstruction (HR, 3.27; 95% CI, 1.19 to 8.95; p=0.021) were associated with stent failure-free survival. A multivariate analysis revealed that the presence of a mid and lower ureteral obstruction (HR, 3.27; 95% CI, 1.19 to 8.95; p=0.007), GPS ≥1 (HR, 7.22; 95% CI, 2.89 to 18.0; p=0.001), and elevated serum creatinine before ureteral stent placement (>1.2 mg/dL; HR, 2.16; 95% CI, 1.02 to 4.57; p=0.044) were associated with stent failure-free survival.

Conclusions

A mid or lower ureteral obstruction, GPS ≥1, and serum creatinine before ureteral stent insertion >1.2 mg/dL were unfavorable predictors of stent failure-free survival. These factors may help urologists predict survival time.