Dusting versus fragmentation for renal stones during flexible ureteroscopy

Objectives: To compare stone dusting and spontaneous passage vs fragmentation and active fragment retrieval during flexible ureteroscopy (fURS) for renal calculi. Patients and methods: The study included patients who underwent fURS and holmium laser lithotripsy for renal calculi from January 2015 to March 2017. Dusting was done using low energy and high frequency (0.3-0.5 J and 15-20 Hz, respectively), and fragmentation was done with higher energy and lower frequency (1-1.2 J and 6-10 Hz, respectively) and then stone fragments were extracted using a basket. The stone-free rate (SFR) was evaluated after 2 months with non-contrast computed tomography. Operative time, complication rate, SFR, and the need for secondary procedures were compared. Results: The study included 107 consecutive patients, with a mean (SD) age of 49 (13) years. Dusting was performed in 51 patients and fragmentation in 56. The patients' demographics, laboratory tests, preoperative stents, stone and renal characteristics were comparable for both groups. Operative time was significantly shorter for dusting than fragmentation (76 vs 91 min, P = 0.009). Complication rates were comparable between the groups (7.8% for dusting and 8.9% for fragmentation, P = 0.840). The mean hospital stay was comparable for both groups (P = 0.686). The SFR was significantly better in fragmentation group (78.6%) compared with the dusting group (58.6%, P = 0.035). The need for a secondary procedure was 33.3% in the dusting group and 23.3% in fragmentation group (P = 0.244). Conclusions: During fURS for renal stones, the dusting technique had a significantly shorter operation time, whilst the fragmentation technique led to a significantly better SFR. Both techniques have comparable safety, hospital stay, and requirement for secondary procedures. Abbreviations: fURS: flexible ureteroscopy/ureteroscope; ICU: intensive care unit; KUB: plain abdominal radiograph of the kidney, ureter and bladder; NCCT: non-contrast CT; SFR: stone-free rate; SWL: shockwave lithotripsy; UAS: ureteric access sheath.