Rigid ureteroscopes with fiberoptic imaging bundles: features and irrigating capacity.

A new ureteroscope design incorporates fiberoptic imaging bundles to replace the rod lens system in a rigid ureteroscope body. These ureteroscopes have evolved along two lines: instruments with a movable eyepiece and those with a small outer diameter (< 10F). The fiberoptic imaging bundles take up less space than the rod lens system. These ureteroscopes thus have a larger working channel than instruments of a similar outer diameter with rod lens imaging systems. Measurement of irrigation rates through a representative sample of these ureteroscopes demonstrated that gravity irrigation was adequate through the empty working channel. However, if an accessory instrument was placed in the working channel, gravity irrigation was insufficient in the smaller models. Manual irrigation was more than adequate under all conditions. The larger models now offer relatively little advantage to counter the decrease in image quality associated with the "honeycomb" fiberoptic image. Nevertheless, the more recent small ureteroscopes allow an adequate irrigant flow while accepting working instruments suitable for a variety of procedures. They thus seem to be ideal for diagnostic ureteroscopy, as they are quick and easy to use, not even requiring ureteral dilation. Furthermore, their small size does not limit their therapeutic applications; on the contrary, it expands them.