Upward migration of indwelling ureteral stents.

Polyethylene ureteral stents suspended from the kidney by a pigtail memory in the proximal end were placed bilaterally in a patient with ureteral obstruction secondary to retroperitoneal sarcoma. Both stents migrated upward and 1 migrated into the renal parenchyma. We recommend that these stents be inserted into the renal pelvis, as opposed to the calices, and that sufficient length be allowed to prohibit migration above the bladder.