الفهرس 
INTRODUCTION&RATIONALOnly 14 pages are availabe for public view
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Abstract
The utilization of a ureteral access sheathas an adjunct toureteroscopywas first reported byTakayasuin 1974 as a means to simplify access to the intrarenal collecting system. It was notuntil more than 2 decades later that the ureteral access sheath was rediscovered, simplifying the deployment and safety ofthese devices.(Takayasu H, 1974)
The ureteral access sheath has been developed to facilitate ureteral re-entry and to allow multiple re-insertions of the ureteroscopeinto the upper urinary tract while reducingtrauma to the distal ureter.(Monga M et al, 2004)
Routine use of the ureteral access sheath during ureteroscopy procedures provides consistent, reliable, access to the upper and lower ureter.The ureteral access sheath is simple in deployment and require no special training to use it. The access sheath facilitates rapid, repeated, and atraumatic access to the upper and lower urinarytracts. The access sheath reduces overall costs and decreases operative times. There is no evidence that the access sheath results in clinically significant ureteral ischemia. The extensive use of the access sheath for long procedures has not increased clinically significant ureteral ischemia nor ureteral stricture formation. (Vanlangendonck R,Landman J, 2004)
Unequivocal data are not yet available to suggest that ureteral access sheath use during ureteroscopy protects or harms the upper urinary tract. The ureteral access sheath also has the potential to improve stone-free rates by allowing active retrieval of fragments. A prospective study is needed to unequivocally determine ifureteral access sheath use is superior in terms of stone-free rates. (Stern JM et al, 2007)
Furthermore, ureteral access sheath in ureteroscopic procedure simplify placement of a ureteral stent through the sheath without the need to reinsert the cystoscope.The stent can be easily placed through the access sheath under fluoroscopic guidance.All urologists who routinely perform ureteroscopic procedures can easily master this timesaving technique. (Wu NZ et al, 2001)
Ureteral access sheath have a big role in controlling the irrigation pressure intrarenal and intraureter during work.New-generation flexible ureteroscopes allow the management of proximal ureteral and intrarenal pathology with high success rates, including complete removal of ureteral and renal calculi. One problem is that