Laser lithotripsy: experience with different laser systems in the treatment of urinary calculi

Two different systems for laserlithotripsy - the Q-switched Nd:YAG laser with an optomechanical coupler and the flashlamp pumped dye laser with integrated optical feedback mechanism are in clinical use for the treatment of urinary calculi at the Department of Urology of the Medical University of LUbeck. Seventy-five patients with ureteral calculi have been treated by laser lithotripsy. Eleven of 15 treatments using the Nd:YAG laser have been performed under visual control with the help of a rigid ureteroscope of 11.5 F. Thirty-five of 42 treatments with the dye laser were carried out with the help of a rigid ureteroscope of 9.5 F. Four patients with the Nd:YAG laser and 7 patients with the dye laser, respectively, have been treated without visual control using a flexible application system and fluoroscopy alone. Both systems showed excellent results. Fourteen of 15 laser lithotripsies with the Nd:YAG laser were successful showing complete (4 cases) or partial (10 cases) fragmentation. The analysis of the failure showed calcium oxalate monohydrate. Thirty-eight of 42 laser 1 ithotripsies with the dye laser were successful. Fragmentation was complete in 26 and partial in 12 cases. The 4 calculi which proved to be failures were all of pale color and 2 of them consisted of cystine alone. Both laser systems are suitable for the treatment of ureteral calculi under visual control or by blind application using fluoroscopy. No serious side effects of the treatment have been observed. Treatment results are satisfactory. Problems may occur in calculi of hard structure using the Nd:YAG laser due to its limited energy and in pale-colored stones using the dye laser due to poor absorption of the laser energy.