Silent ureteral stones: impact on kidney function--can treatment of silent ureteral stones preserve kidney function?

Objective: To report our experience with silent ureteral stones and expose their true influence on renal function.

Methods: We analyzed 506 patients who had undergone ureterolithotripsy from January 2005 to May 2010. Silent ureteral stones were calculi found in the absence of any specific or subjective ureteral stone-related symptoms. Of the 506 patients, 27 (5.3%) met these criteria (global cohort). All patients were assessed postoperatively with dimercaptosuccinic acid scintigraphy (DMSA). A difference in relative kidney function of >10% was considered abnormal. Pre- and postoperative comparative DMSA analyses were electively obtained for 9 patients (kidney function cohort). A t test was used to assess the numeric variables, and the chi-square test or Fisher's exact test was used for categorical variables. Two-tailed P<.05 was considered statistically significant.

Results: Stones were diagnosed by radiologic abdominal evaluation for nonurologic diseases in 40% and after previous nephrolithiasis treatment in 33%. The primary therapy was ureterolithotripsy in 88%. The mean follow-up time was 23 months. The overall ureteral stone-free rate after 1 and 2 procedures was 96% and 100%, respectively. In the global cohort, the mean pre- and postoperative serum creatinine levels were similar (P=.39), and the mean postoperative function on DMSA was 31%. In the kidney function cohort, no difference was found between the pre- and postoperative DMSA findings (22%±12.1% vs 20%±11.8%; P=.83) and serum creatinine (0.8±0.13 mg/dL vs 1.0±0.21 mg/dL; P=.45).

Conclusion: Silent ureteral stones are associated with decreased kidney function present at the diagnosis. Hydronephrosis tends to diminish after stone removal, and kidney function remains unaltered.