Factors associated with total laser energy use and lasing time during ureteroscopic holmium: YAG laser lithotripsy: a retrospective observational study

Urolithiasis is one of the most common conditions encountered in urological practice and affects millions of individuals worldwide. Holmium: yttrium-aluminum-garnet (Ho: YAG) laser lithotripsy is widely used for stone fragmentation during ureteroscopy (URS). However, factors associated with total laser energy use and lasing time have not been evaluated collectively. This study aimed to evaluate preoperative patient- and stone-related factors associated with cumulative Ho: YAG laser energy use and lasing time during ureteroscopic lithotripsy. We retrospectively analyzed 183 ureteroscopic procedures performed at An-Najah National University Hospital. Stone lithotripsy was performed using a holmium: yttrium-aluminum-garnet (Ho: YAG) laser platform with a maximum rated output of 150 W and 272- or 365-µm laser fibers (MultiPulse HoPLUS). Noncontrast computed tomography was used to assess stone characteristics, including stone volume (calculated using the ellipsoidal formula), mean Hounsfield units (HU), and anatomical location.Intraoperative parameters, including total laser energy (kJ) and lasing time (seconds), were recorded in a standardized manner. Gamma generalized linear models with a log link were used for multivariable analysis of factors associated with energy applied and lasing time. A total of 183 ureteroscopic procedures were included. The median age was 49 years (IQR, 35–61), and 132 procedures (72.1%) involved male patients. In the multivariable Gamma-log model for energy applied, stone volume (exp(β) = 1.00017; 95% CI, 1.00004–1.00031; p = 0.01), HU (exp(β) = 1.00058; 95% CI, 1.00012–1.00105; p = 0.01), and renal involvement (exp(β) = 1.68; 95% CI, 1.18–2.41; p = 0.004) were associated with greater energy applied. For lasing time, stone volume (exp(β) = 1.00019; 95% CI, 1.00009–1.00029; p < 0.001), HU (exp(β) = 1.00052; 95% CI, 1.00017–1.00086; p = 0.004), renal involvement (exp(β) = 1.45; 95% CI, 1.11–1.89; p = 0.007), age (exp(β) = 1.01; 95% CI, 1.00–1.02; p = 0.046), and multiple stones (exp(β) = 1.46; 95% CI, 1.00–2.11; p = 0.048) were associated with longer lasing time. In this single-center retrospective study, greater stone volume, higher HU, and renal involvement were associated with greater laser energy use; these factors, together with age and multiple stones, were associated with longer lasing time. Prospective validation is required before these associations can be used for individualized preoperative prediction or procedural planning.