INTRODUCTION
During the past decades, the surgical treatment of kidney stones has undergone many technological advances and retrograde intrarenal surgery (RIRS) became one of the standard treatments for patients with renal stones. The ureteral access sheath (UAS) was developed in 1974 by Hisao Takayasu&Yoshio Aso [1] and it is often used during RIRS to facilitate entry of flexible ureteroscopes into the renal collecting system. Additionally it facilitates easy re-entry into the collecting system, consequently shortens the operating time, improve vision, decrease intrapelvic pressure and increases the flexible ureteroscope’s life span [2-5]. Currently, UASs are produced with various characteristics, including various lengths, diameters, materials, dilator tip designs, radiopaque markers and stiffness [6].Selection of the UAS among the choices of manufacturers and models typically depends on physician familiarity, cost, and size of ureteroscope.
Despite their advantages, there are some important misgivings concerning to UAS use. UAS usage entails a risk of ureteral damage including involving the smooth muscle layer after insertion [7]. Additionally to the over distention created by a UAS may decrease ureteral blood flow and theoretically induce long-term ureteral stricture formation [8]. In addition to that, a previous study reported that a large sized UAS had a more effect on ureteral blood flow [9]. Therefore, a UAS with a small outer diameter and large inner diameter is considered to be ideal in clinical practice.
To our knowledge; there is no prospective study in the international literature has evaluated the effect of UAS related ureteral injury and possible ischemia on the development of ureteral stricture. In the current study, we aim to analyze intraoperative, postoperative complications and the incidence of ureteral injury with using smallest diameter UAS on the market and the effect of injuries and possible ischemia/inflammatory changes on the risk of ureteral stricture development in the long term.