Ureteral stents — materials and new forms

Abstract

Three different types of polymers are currently used for self-retained ureteral stents: thermoplastic materials such as polyurethanes, and thermoset elastomers such as silicone and hydrogels. Polyurethane stents are easy to form and have high drainage capacity, whereas silicone shows the best biocompatibility but a lower drainage efficacy than the former. A mock urinary system consisting of a “collecting system” and a 9-F tube was used to evaluate the flow characteristics of various double-pigtail stents in cases of urinary obstruction. For simulation of an unobstructed urinary system a human urogenital system was used. “Inner flow” polyurethane stents showed the best drainage as compared with “inner flow” silicone and “outer flow” ESWL stents in an obstructed ureter, whereas ESWL stents maintained the best flow in an unobstructed ureter or in respect to conventional stents with obstructed sideports.