Polyurethane internal ureteral stents in treatment of stone patients: morbidity related to indwelling times.

The morbidity and complications associated with use of internal polyurethane ureteral stents in a series of 290 stone patients treated endourologically or with extracorporeal shock wave lithotripsy were retrospectively reviewed. Of the 299 stents retrieved 141 were also tested for patency to relate the rate of luminal blockage with stent caliber, indwelling time and clinical evidence of obstruction in the stented tract. Stent indwelling times ranged from a few days to 18 months: 11.3% were indwelling longer than 6 months and 1.9% were lost to followup. Incrustation occurred in 9.2% of the stents retrieved before 6 weeks, 47.5% indwelling 6 to 12 weeks and 76.3% thereafter. In 19 cases over-all (6.4%) an auxiliary procedure was required to decrease incrusted stone burden and enable stent retrieval. Other complications included stent migration (3.7%), infection (6.7%) and breakage (0.3%). Despite a 30% rate of luminal blockage in stents retrieved after indwelling times up to 3 months, the incidence of clinical obstruction in stented tracts up to 3 months was 4%, confirming other reports that significant urine flow occurs around rather than through hollow, vented stents. Our findings underline the importance of restricting the use of stents to stone patients who will be reliable at followup. Morbidity was minimal if stent indwelling times did not exceed 6 weeks.