Pulsed dye laser lithotripsy for ureteral stone fragmentation

Area of Science:

• Urology
• Nephrolithiasis Research
• Laser Lithotripsy Technology

Background:

• Ureteral stones pose a significant clinical challenge.
• Laser lithotripsy is a common treatment modality for urinary calculi.
• Efficacy varies based on stone composition and lithotripter technology.

Purpose of the Study:

• To evaluate the efficacy of a second-generation, high-power dye-laser lithotriptor (Pulsolith) for ureteral stones.
• To investigate the fragmentation of different stone compositions, including calcium oxalate monohydrate, dihydrate, phosphate, and cystine stones.
• To assess the impact of optical coupling and immersion solutions (rifampicin, tetracycline) on fragmentation rates in vitro.

Main Methods:

• Prospective study involving 35 patients with ureteral stones treated with the Pulsolith dye-laser system.
• In vitro experiments were conducted to test fragmentation of cystine and calcium oxalate stones.
• Cystine stones were immersed in rifampicin or tetracycline solutions, with and without optical coupling, to measure fragmentation efficacy.

Main Results:

• Ninety percent of calcium oxalate monohydrate stones were fragmented.
• Calcium oxalate monohydrate stones required higher total energy for fragmentation compared to calcium oxalate dihydrate or phosphate stones.
• Cystine stones demonstrated significant resistance to dye-laser lithotripsy, with in vitro fragmentation rates only 10% of that for calcium oxalate stones, even with optical coupling and immersion solutions.

Conclusions:

• The Pulsolith dye-laser lithotriptor is effective for most ureteral stones, particularly calcium oxalate monohydrate.
• Cystine stones remain largely resistant to current dye-laser lithotripsy techniques.
• While optical coupling may enhance the photo-acoustic effect, it does not overcome the inherent resistance of cystine calculi to this lithotripsy method.