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There are considered characteristics of the laser medical devices working at the wavelengths 1.94; 2.01 and 2.1 µm, which are used in urology for surgical operations. It is shown that unlike action in the air environment, section of the biotissue in the water environment (physiological solution) is performed by the steam-gas stream which is formed as a result of superintensive boiling in thin (about 0.1 mm) a liquid layer in which absorbed laser radiation. Coagulation of the biotissue, adjacent to a section, happens due to heat which is produced via vapor condensation.

Currently, transurethral resection of a bladder tumor (TUR) is the gold standart treatment for non-muscle invasive bladder cancer (NMIBC). Standard TUR for a bladder wall tumor has a high recurrence rate, which is caused mainly by malignant cell implantation during the surgery. Besides, specimens obtained with conventional TUR are insufficient for accurate pathological staging. The non-conformity of the standard TUR with the established oncological principle of dissecting through normal tissue prompted a search for the optimal surgical modality. En-bloc resection of the bladder wall tumor has been proposed as an alternative method for surgical management of NMIBC. This technique involves the resection of bladder tumor through the underlying muscle layer as a single piece thus providing high quality material for subsequent morphological study and reducing the risk of metastasizing by implantation of malignant cells. This paper presents an analysis of relevant research literature published in the last twenty years, describes all currently existing techniques of the bladder tumor resection using a variety of energy sources, including laser.

Aim Experimental evaluation of the efficacy and safety of lithotripsy using a new pulsed thulium fiber laser operating at a wavelength of 1.94 microns, peak power of 500 watts (maximum average power of 50 watts) by comparing it with a holmium laser operating at a wavelength of 2.1 microns (average maximum power 100 W and 120 W). Relevance The proportion of minimally invasive surgery in the management of urolithiasis, including retrograde intrarenal surgery, is steadily growing. The most appropriate tool for stone destruction is a laser. To date, the gold standard of minimally invasive surgical treatment of nephrolithiasis is holmium laser lithotripsy, which uses a laser on yttrium-aluminum-garnet activated by holmium ions (Ho: YAG) operating at a wavelength of 2.1 m. However, in recent years, lasers on a Tm-activated fiber with a wavelength of 1.94 m have become increasingly popular since the water absorption coefficient for the Tm radiation of a fiber laser is 5.5 times higher than for a Ho: YAG laser and in 2.2 times higher than for the Tm: YAG laser. This difference may translate into greater effectiveness and speed of stone crushing, which in turn leads to shorter operating time. Materials and methods This article describes physical foundations of holmium and thulium laser radiation, the mechanisms of stone fragmentation, data from a series of experiments comparing the efficiency and safety of ex-vivo lithotripsy using a holmium solid-state laser with a wavelength of 2.1 m and a thulium fiber laser with a wavelength of 1.94 m. Results The study findings suggest that the STA IRE-Polyus thulium fiber laser operating at a wavelength of 1.94 microns and a maximum power of 500 watts has several advantages over the holmium laser in the stone fragmentation in urological practice. Conclusion The results of the experimental work allow us to conclude that the use of a thulium fiber laser operating at a wavelength of 1.94 m and a maximum peak power of 500 W enables highly effective and safe lithotripsy.