Introduction: Double-J ureteral stents are subject to encrustation. Studies have shown that the encrustation onset is linked with indwelling time. In prevention, it is admitted that the Double-J stent indwelt for medium or long term should be replaced periodically. However, in the absence of guidelines, indwelling durations vary with centers' habits, stent indication, and stent materials. Our target was to evaluate the actual ureteral stent medium-/long-term indwelling times and related encrustation rates perceived by urologists in daily practice. Methods: An observational retrospective study was performed over six European centers. All data of all consecutive removed stents of the same material implanted for more than 2 months within a same 2-year referred period were collected. Three stent types of various materials, with/without coating, were evaluated. Encrustation rates were analyzed according to indwelling times and stent indication. Results: Four hundred seventy-three stents were recorded with indwelling times between 60 and 679 days. An unexpected number of long-term indwelling times were noticed: globally one-third more than 6 months, and 9% more than 1 year. In case of malignant indication, these rates were, respectively, 44% and 17%. For nonstone indication, clinically significant encrustation rates stayed extremely low before 4 months (1.3%) and quite low before 6 months (5.2%), increasing with time to reach around 10% in the long term. However, as expected, the rate was higher for stone indication with a marked increase after 4 months (8% before 4 months, nearly 17% after). Conclusion: Our data confirm a higher encrustation risk for stone patients. Long indwelling times in nonstone patients beyond 6 months or even 12 months appear to be still requested and relatively well supported in usual practice by this population.

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