Application of resonance metallic stents for ureteral obstruction

• 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.

• 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.

• 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.

• 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.