Can radiological scores predict difficulties in removal of encrusted ureteral stents?

In the present study, we aimed to report our single-center experience in encrusted ureteral stent management and to compare the utility of two different scoring systems in patient management. This is a retrospective study of patients who underwent various surgical procedures to remove encrusted ureteral stent. Encrusted stent grading was performed using KUB and FECal grading sytems. FECal grading system scored from Grade 1 to Grade 5 according to stone size, location, and degree of stent incrustation and the KUB score is the sum of the stone burden scores of three different parts of an encrusted stent within the kidney, ureter, and bladder determined using a scale from 1 to 5 according to the maximal diameter of encrustation. We compared these two classifications for the prediction of perioperative outcomes. Fifty patients were included in the study (52% female, mean age 48 years). The mean time from ureteral stent insertion until diagnosis of encrustation was 11.4 ± 13.6 months. High-grade incrustations (FECal Grade 3, 4, and 5) accounted for 62% of cases. The mean KUB score was 9.8 ± 2.7. The average number of procedures required to remove the stent was 1.71 ± 1.38. Multimodal surgery was required to remove 42% of the stents. Both, a total KUB score ≥ 9 and high-grade FECal classification were found to be significant predictors of longer operative time (> 100 min), need for multiple surgeries, and need for invasive surgery. While high-grade FECal classification showed a significant association with need for multimodal surgery (OR 6.92, p = 0.008), a total KUB score  ≥  9 showed no association (OR 2.91, p = 0.086). These two scores seem to be good indicators in predicting difficulties for surgical management of encrusted ureteral stent with a clear advantage of the FECal score in terms of prediction of multimodal surgery.