Ureteral stents have been widely used in many urological operations. The main purposes of placing ureteral stents include improvement of ureteral obstruction, protecting renal function and drainage of infection. Although there are several reports regarding the effectiveness of long-term ureteral stents for malignancy ureteral obstruction, ureteral stricture and urolithiasis, the experience is limited about the long-term ureteral stents made by Taiwan. Thus, The investigators will conduct this post-marketing survey to observe and investigate the changes of ureteral stents, e.g. hydronephrosis, infection and stone formation. Now this product has been approved by European Medical Device Administration. The investigators have to propose the 5-year post-market survey report. Though this observation study, The investigators can further understand the clinical safety and effectiveness of placing ureteral stents