Application of resonance metallic stents for ureteral obstruction

Abstract

Study Type – Therapy (case series) Level of Evidence 4 OBJECTIVE To determine the effectiveness of the Resonance ureteral stent and clarify the risk factors that lead to stent failure. In the present study, we review our clinical experiences using Resonance stent in treating malignant and benign ureteral obstruction. PATIENTS AND METHODS Nineteen patients with extrinsic malignant ureteral obstruction (n= 15) and benign stricture (n= 4) were retrospectively evaluated. All patients had received Resonance stent insertion through antegrade or cystoscopic retrograde approaches. The pre‐insertion and follow‐up interventions included image studies and biochemical tests. The insertion success rate, obstruction patency rate and complications were reviewed. For categorical variables, the chi‐square test and Fisher’s exact test were carried out to determine associations between variables. RESULTS The technical success rate of stent insertion was 84.6%. The mean follow‐up was 5 months (range 1–10.5 months). Five stents failed to alleviate the obstruction, and the patency rate was 77.3% (17/22). Patients who had had previous radiation therapy had a lower ureter patency rate in comparison with non‐radiation patients (50% vs 92.3% respectively, P= 0.039). The 6‐ and 9‐month patency rates were 81.0% with 11 stents and 27.0% with 3 stents, respectively. CONCLUSIONS The results of the present study demonstrated that malignant or benign ureteral obstruction could be treated safely and sufficiently with the Resonance metallic stent. Careful patient selection is critical to achieve successful results. For malignant ureteral obstruction, previous radiation therapy is a risk factor for stent failure.

Outcomes of Metallic Stents for Malignant Ureteral Obstruction

“…Stent failure occurred in 1 patient with an ileal conduit in concordance with previously reported higher rates of metallic stent failure in this population. 16 XRT, which has been shown to predict failure with metallic stents in 1 previous study, 14 was not associated with a significant difference in outcome in this series (p ϭ 0.244).…”

“…14 In contrast, another study reported no difference in stent outcomes between XRT and nonXRT cases. 11 XRT did not appear to predict outcome in our series.…”

“…[11][12][13][14][15] Overall failure rates in cohorts including MUO and nonMUO cases have ranged widely from 7% to 66%. [11][12][13][14][15] Of note, although no prior studies have focused exclusively on patients with MUO, this subset of patients was found to have higher failure rates in 3 previous series. 11,14,15 Other series have demonstrated equivalent 13 or even improved outcomes 12 in patients with MUO.…”

“…For this analysis our definition of failure was similar to comparable studies, [11][12][13][14][15] as unplanned stent exchange or nephrostomy tube placement for signs or symptoms of recurrent ureteral obstruction (recurrent hydroureteronephrosis or increasing creatinine). In applying this standard to our cohort of 37 stents placed for MUO, a failure rate of 35% was identified.…”

“…[11][12][13][14][15] Of note, although no prior studies have focused exclusively on patients with MUO, subset analyses revealed higher failure rates with MUO in multiple series. 11,14,15 Given the indefinite need for urinary diversion in MUO, these patients would benefit a great deal from more durable ureteral stents. Therefore, we reviewed the outcomes of this stent when placed specifically for MUO.…”