[Laser-tissue interactions in urology].

The laser-tissue interaction is a complex phenomenon which is usually classified into 4 distinct mechanisms: electro-mechanical action, photoablative action, thermal action and photochemical action. Fragmentation of calculi by means of a pulsed dye laser is a good example of the electro-mechanical action. The thermal action can induce coagulation and/or volatilisation of tissues. Treatments of bladder tumors, urethral strictures and more recently benign prostatic hypertrophy are based on the laser terminal action.