A comparison of the FREDDY and holmium lasers during ureteroscopic lithotripsy

Two laser devices that are used today in endoscopic treatment of renal and ureteral calculi are the frequency-doubled double-pulse neodynium:YAG (FREDDY) and Holmium:YAG lasers. The mechanism of action of these lasers differs, thus conferring potentially different safety and efficacy profiles. The in vitro efficacy of these lasers in treating urinary stones has been explored, but to our knowledge no study compares the in vivo efficacy. The purpose of this study is to compare the stone-free and complication rates of the FREDDY and holmium lasers.

Subjects were included in the study (from January 2004 to September 2006) if they had adequate documentation of stone size and location, postoperative stone burden, and perioperative complications. Stone-free status was determined based on intraoperative findings and postoperative imaging. Complications included bleeding, ureteral perforation, any intraoperative event necessitating termination of the procedure, ureteral stricture, hydronephrosis, and admission to the hospital with a diagnosis related to the procedure.

Sixty patients with adequate follow-up were identified. Thirty patients were treated with FREDDY and 30 patients with Holmium laser. Fisher's exact test was employed for statistical analysis. There was no significant difference in the average stone size between the FREDDY and Holmium groups, which were 6.7 mm and 6.1 mm, respectively. Stone-free rates in the FREDDY and Holmium groups were 76.7% and 93.3%, respectively, P = 0.149. The complication rates were 17.4% in the FREDDY group and 10% in the Holmium group, P = 0.667.

The complication and stone-free rates did not significantly differ between the FREDDY and Holmium lasers, though there was a trend toward a higher stone-free rate and lower complication rate with the holmium laser. Holmium laser may be more effective than the FREDDY laser in fragmenting calcium oxalate monohydrate stones. The device and laser fiber costs were comparable.