The purpose of this study is to evaluate Efficacy and Safety of a covered self-expandable dual-layered metallic mesh stent (UVENTA) in ureteral obstruction.

Prospective, Multi-center, open label, single arm Study

1. Treatment

   - Covered self-expandable dual-layered metallic mesh Stents(cSEMS) are implanted in patents with malignant ureteral obstruction

2. Follow up

   • Assessments including X-ray(KUB), are done 3, 6, 12, 18 and 24 months after the procedure.
   • Diuretic RI scan (DTPA, MAG-3) 3, 6, 12 months after the procedure
   • Imaging such as IVP(Intravenous Pyelogram), ultrasonogram, CT(Computed Tomogram) are performed at 6 and 12 months.

Inclusion Criteria:

1. Patients who voluntarily agree to participation and submitted a written informed consent for this study, and 20~80 years

2. One out of following cases below apply to Patients who have malignant ureteral obstruction or have benign ureteral obstruction without improvement after previous treatment

   • Patients who doesn't want to have regular replacement of plastic stent
   • Patients who has no improvement of obstruction after plastic stent implant
   • Patients who want other Urinary diversion because of stimulatory sign or pain due to plastic stent

3. Patients with no previous ureteral metal stenting procedure experience.

4. Patients with more than 6 months of life expectancy

5. Patients understanding the objective of the study and who are willing to sign a consent

Exclusion Criteria:

1. Patients with Urothelial Carcinoma
2. Patients with bladder invasion of malignant tumor
3. Patients with bladder dysfunction or obstruction of lower urinary tract
4. one or more times Recurrent Urinary stone in the last 3 years
5. 2 or more times upper urinary tract infection without upper urinary tract obstruction
6. Karnofsky scores < 60
7. Patients with Bacteriuria
8. Inadequate Patient to participate in the study as judged by the investigator