This is a prospective non-randomized clinical study to evaluate the efficacy of the Memokath 051 ureteral stent in managing extrinsic malignant ureteral obstruction secondary to an inoperable abdominal or pelvic malignancy or secondary to changes caused by surgery, chemotherapy, or radiation for pelvic and/or abdominal malignancies. Enrollment of study subjects will take place over a period of two to three years for to a total of 15 patients.