We herein report on 304 consecutive cases of bladder stones treated by electrohydraulic lithotripsy. The special armamentarium is described. The average age for male patients was 68.5 years, the oldest being 102 years, and for female patients it was 63.9 years. Of the patients 38.5 per cent were high risk. The weight of the transurethrally removed stones ranged from 1 to 135 gm. In 70.4 per cent of the male patients transurethral resection of the prostate was done under the same anesthesia and technical problems were encountered in 12 operations (4 per cent). Bladder perforations occurred in 5 patients but cystotomy and drainage were necessary in only 1 (0.3 per cent).

After in vitro and in vivo endoscopic laser investigation on normal and experimentally strictured urethras in dogs transurethral laser urethrotomy was done on men. A neodymium: yttrium aluminum garnet laser with a flexible laser light guide was used. The endoscope developed for this purpose is described in detail. The first laser operations were without complications.

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A capacitively coupled transverse radio frequency discharge has been successfully applied to excite a gasdynamically cooled supersonic CO laser operating at 105 K in a semiclosed gas cycle. The laser head is characterized by a very compact design and a high discharge power density (160 W/cm3). At a discharge pressure of 390 mbar a maximum laser output of 6 kW is obtained with an efficiency of 12.4%.

The beam quality of a gasdynamically cooled CO laser with an unstable resonator (M = 1.7) has been improved by use of an extracavity cylindrical mirror. This mirror corrects the phase distortion resulting from the supersonic f low. A 4.5-kW laser beam with a total divergence of 1.4 mrad is obtained with an efficiency of 9% and a Strehl ratio of 0.4. A strong degradation of the beam quality has been observed outside the resonator owing to water-vapor absorption. The use of dry air in the beam-guiding system signif icantly reduces this effect of thermal blooming.