Impact of stone density on the total laser time and other surgical outcomes in flexible ureteroscopy

Background and objectives: Several preoperative factors are assessed for the evaluation of operative time and fragmentation efficacy during retrograde intrarenal surgery. Due to limited energy capabilities, stone density is an important factor contributing to procedural time. This study aimed to evaluate the effect of stone density on the total laser time in lithotripsy. Methods: We conducted a cross-sectional prospective analysis where fifty-two patients who underwent flexible ureteroscopy using the Cyber Ho 60 holmium laser system (Quanta System) were prospectively analyzed from October 2017 to November 2020 in a cross-sectional study. These patients were divided into groups according to their stone attenuation values (Hounsfield units) and were followed up for 3 months to determine the success of stone clearance. Results: The mean stone size and density were 14.44 mm and 1043 Hounsfield units, respectively. Furthermore, the mean total laser time was 26.58 minutes, whereas the mean operative time was 41.44 minutes. The total laser time did not significantly differ between stones with attenuation >1000 and those with attenuation <1000 (p = 0.486). Stones measuring >13 mm in size required considerably longer lasering time than their smaller counterparts (p = 0.008). Conclusion: In the era of rapid laser technology and instrumental developments, our findings suggest that stone density has no value on the outcomes of flexible ureterorenoscopy, including the total lasering time, stone-free rate, and overall complications. In contrast, stone size significantly influences the total laser time and stone-free rate.