Disposable Ureteral Stents

The Disposable Ureteral Stents (Types C and D) are flexible, double-pigtail plastic tubes composed of polyurethane with hydrophilic coating, used for temporary internal drainage from the kidney to the bladder to relieve urinary obstruction. The stents are placed via endoscopic technique and are labeled for single use with a maximum indwelling time of 30 days; a silk thread attachment must be removed after 14 days.

The subject device differs from the predicate (Cook Universa Firm Stents) in labeled indwelling time (30 days vs. 12 months), available sizes (4.0–8.0 Fr vs. 5.0–8.0 Fr), stent lengths (14–28 cm vs. 18–32 cm), pusher tube specifications, and guide wire dimensions. Both use polyurethane with hydrophilic coating and double pigtails; sterilization is EtO for both.

Testing followed FDA guidance 'Guidance for the Content of Premarket Notification for Ureteral Stents' (1993), ISO 10993-1 for biocompatibility, ISO 11135:2014 for sterilization, and ASTM 1828-22 'Standard specification for ureteral stents.' Biocompatibility endpoints included cytotoxicity, sensitization, acute/subacute systemic toxicity, and genotoxicity.

Both devices share identical indications for use (temporary internal drainage to relieve benign, malignant, and post-traumatic urinary obstruction via endoscopic placement), the same material composition and coating, equivalent sterilization method, and double-pigtail design. Non-clinical bench testing demonstrated that technological differences (size range, indwelling time labeling) do not raise different safety or effectiveness questions, establishing substantial equivalence to the predicate device.