Drainage of Malignant Extrinsic Ureteral Obstruction Using the Memokath Ureteral Stent

Long-Term Temporary Drainage of Malignant Extrinsic Ureteral Obstruction Secondary to Inoperable Pelvic or Abdominal Malignancies Using the Memokath 051 Ureteral Stent

The purpose of this study is to evaluate the safety and efficacy of the Memokath 051 ureteral stent as a long-term temporary and minimally invasive means of providing ureteral drainage in the setting of malignant extrinsic ureteral obstruction secondary to inoperable abdominal or pelvic malignancies. Up to 15 adults who have extrinsic ureteral obstruction secondary to an inoperable abdominal or pelvic malignancy and need ureteral stent drainage will undergo outpatient placement of the ureteral stent. Ongoing monitoring will continue for as long as the stent is in place.

The Memokath 051 ureteral stent is a device designed to provide long-term temporary ureteral drainage in the setting of extrinsic ureteral obstruction secondary to inoperable pelvic and abdominal malignancies or secondary to changes caused by surgery, chemotherapy, or radiation for pelvic and/or abdominal malignancies. The management of malignant extrinsic ureteral obstruction secondary to inoperable neoplastic disease of the abdomen or pelvis is a common urologic problem, and has important implications for a patient's quality as well as quantity of life, which has been estimated to generally range between 6.5 to 23 months in this population. Currently, extrinsic ureteral obstructions are usually managed with double-J ureteral stents, placed either cystoscopically, or antegrade via a percutaneous nephrostomy tube. Double-J stents are prone to encrustation and obstruction over time, necessitating stent exchange under general anesthesia every 3 to 4 months. These repeat surgical procedures under general anesthesia carry subsequent risks of infection, drug reactions, and iatrogenic injury, leading to degradation in the quality of life of these patients who often have a year or less to live. To circumvent these disadvantages, the nickel-titanium Memokath 051 ureteral stent was developed to provide a means of minimally invasive long-term temporary ureteral drainage. 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. A control group 10 patients with extrinsic ureteral obstruction secondary to an inoperable pelvic or abdominal malignancy or secondary to changes caused by surgery, chemotherapy, or radiation for pelvic and/or abdominal malignancies and treated by other urologic staff surgeons in a standard fashion with retrogradely placed double-J stents will also be followed every 3 to 4 months.

The Memokath 051 ureter stent is used for the treatment of malignant or benign ureteric strictures in both men and women. The stent design consists of a tightly-coiled nickel-titanium alloy, with a diameter of 10.5 French (Fr) and a fluted proximal diameter expanding to 22 Fr. The stent is manufactured in multiple lengths which are chosen to position the device across the narrowed area rather than crossing the ureteropelvic or ureterovesical junction. It has a thermal memory system for its predetermined shape; the stent softens at temperatures below 10 degrees Celsius but regains its shape when heated above 55 degrees Celsius.

A JJ stent is a flexible plastic tube that drains urine from the kidney to the bladder and is supposed to stay in place temporarily. There is a coil on each end to keep the stent in place, preventing the stent from migrating down and out from the kidney or up from the bladder into the ureter. The stent can stay in place for few weeks to 3 months or more depending on the indication. If left for more than 6-9 months some stents may get encrusted leading to stone formation around the stent.

Stent dwell time is defined as the amount of time a stent can remain in the body after it placed, before it needs to be removed due to failure.

Inclusion Criteria: Presence of extrinsic ureteral obstruction secondary to inoperable pelvic or abdominal malignancy or secondary to changes caused by surgery, chemotherapy, or radiation for pelvic and/or abdominal malignancies who have had >2 standard double J stent exchanges with no prospect of being stent-free Life expectancy greater than 4 months Adult patient (18 years of age or older) Preoperative medical examination clearing the patient for general anesthesia No active urinary tract infection by urinalysis and urine culture. Exclusion Criteria: Ureteral obstruction of a benign or intrinsic etiology Lower urinary tract abnormality precluding cystoscopic stent placement Patients with a solitary kidney Patients not willing or unable to receive their post-operative follow-up at the Mayo Clinic in Rochester, Minnesota Pregnant female patient.