Effects of Laser Probes and Computed Tomography Findings on Ureterorenoscopic Laser Lithotripsy Success Rate, Laser Time, Laser Energy Level and Operative Time for Distal Ureteral Stones

Objective: To investigate the effect of preoperative non-contrast computed tomography (NCCT) findings and peroperative laser probe selection on total laser time, energy level and ureterorenoscopy (URS) time for distal ureteral stones. Materials and Methods: We prospectively evaluated 72 patients with single distal ureteral stone measuring 5-25 mm in diameter on NCCT, who were treated with ureteroscopic lithotripsy (URSL) between June 2015 and October 2016. The patients were divided into two groups according to probe selection as 365 mu m and 550 mu m groups. Stone diameters, stone volume and Hounsfield units (HU) measured on NCCT, and URSL findings were noted at the end of the treatment. These findings were compared between the groups. Also the possible predictive value of NCCT findings was evaluated for URSL data. Results: There were 17 patients in the 365 mu m and 55 patients in the 550 mu m groups. There was no significant difference in URSL success rate and other predictive data between the groups. However, among the peroperative data, laser time, laser energy level and laser energy/time ratio were significantly lower in the 365 mu m group compared to the 550 mu m group (p<0.05). Correlation analysis indicated that total laser time and URS time were correlated with stone diameter, stone volume, HU values and density (HD). Laser energy level was only correlated with longitudinal stone diameter and HD. Conclusion: Stone diameter, volume and HU values are significant predictors of laser energy level, URS and laser time for distal ureteral stones. Also, use of a thinner probe decreases total laser time, laser energy level and laser energy/time ratio. In addition, thinner laser probe shortens URS time.