Safety and efficacy of ureteral access sheaths.

The ureteral access sheath (UAS) was introduced as a means of passing a flexible ureteroscope. Although the device was initially lauded for its ability to facilitate ureteroscopic access, passage was difficult and risked ureteral injury, and the UAS fell out of favor until the development of a new generation of devices that was easier to insert. The UAS should be advanced under fluoroscopy over a stiff guidewire, and the surgeon should ensure copious hydration of all inner and outer surfaces. Use of the UAS is purported to improve irrigant flow and visibility. The UAS can induce transient ureteral ischemia and promote an acute inflammatory response, but it also prevents potentially harmful elevations in intrarenal pressure. Unequivocal data are not yet available to suggest that UAS use during ureteroscopy protects or harms the upper urinary tract. The UAS also has the potential to improve stone-free rates by allowing passive egress or active retrieval of fragments. A large prospective study is needed to unequivocally determine if UAS use is superior in terms of stone-free rates. Cost studies reported to favor UAS use, although a formal cost-effectiveness analysis has not been performed. Further study is needed before routine use of the UAS can be recommended.