Discolored ureteral stents: Findings in urinalysis and urine culture

Objective: Discolored ureteral stents are sometimes encountered in daily clinical practice; however, the mechanism(s) underlying the development of discolored ureteral stents remain unknown. In this study, we retrospectively analyzed the characteristics of discolored ureteral stents based on the results of a urinalysis and urine culture. Materials & Methods: We identified a total of 26 patients with discolored ureteral stents and compared the findings in the urinalyses and urine culture in 21 discolored versus 45 non-colored ureteral stents. Results: The median and mean (±SD) duration of stenting time was 78.0 and 81.3 (± 21.3) days for the discolored ureteral stents and 69.0 and 74.9 (± 19.8) days for the non-colored ureteral stents, respectively (P = 0.25). The discolored ureteral stents were associated with a higher mean urine pH than the non-colored ureteral stents (mean: 6.4 vs 6.0, P< 0.05). There were no significant differences between the two groups in the RBC (P = 0.51) and WBC (P = 0.35) counts in the urinalyses. In addition, the rate of a positive culture in the patients with discolored stents [20 of 21 (95.2%)] was significantly (P <0.01) higher than that observed in the patients with non-colored ureteral stents [33 of 45 (73.3%)]. Conclusions: In this study, the subjects with discolored ureteral stents showed a significantly higher likelihood of having a positive urine culture and also demonstrated higher pH values in the urinalyses. However, no clear cut-off point to predict discoloration was indicated.