The Effect of Ureteral Access Sheath Use/Caliber Change on Outcomes of Retrograde Intrarenal Surgery, Short-Term Kidney Functions, Radiation Exposure, Ureteroscope Lifetime, and Factors Predicting Insertion Failure: A RIRSearch Study.

Background: The aim of this study was (1) to explore effect of ureteral access sheath (UAS) use on primary retrograde intrarenal surgery (RIRS) outcomes, short-term kidney functions, radiation exposure, and ureteroscope lifetime (URS-LT) and (2) to reveal factors that predict UAS insertion failure. Materials and Methods: Patients ( n  = 1318) who underwent RIRS without UAS (Group 1), those who had operation with a <11-13 Fr (Group 2), and those with a ≥11-13 Fr UAS were matched (1:1:2) and compared. Stone-free rate (SFR), intra- and postoperative complications, acute kidney injury (AKI), fluoroscopy time, URS-LT, and UAS insertion failure were the outcomes. Results: SFR, which was highest in Group 3 (75%, 71% and 87.3%, respectively; P  = .001), was significantly associated with use of ≥11-13 Fr (odds ratio [OR]: 4.2, P  < .001), but was not with use of <11-13 Fr UAS (OR: 1.3, P  = .3). Group 3 had less need for auxiliary procedure (15%, 16%, and 7.4%, respectively; P  = .03). Five percent of patients had a risk of AKI, but only 0.3% developed AKI. Although UAS use was protective against creatinine increase (OR: 0.65, P  = .02), increased risk of AKI was only associated with female gender (OR: 5.5, P  < .001). Fluroscopy times were 5, 15, and 87 sn, respectively ( P  < .001). Short URS-LT was strongly associated with high frequency of lower calix stones ( r  = -0.94, P  = .005), but URS-LT was not correlated with sheathless case rate ( r  = 0.59, P  = .22). UAS insertion success in first attempt was more likely in younger (OR: 0.99, P  = .03), hydronephrotic (OR: 3.4, P  < .001), and female cases (OR: 1.5, P  = .008). But absolute UAS insertion failure was associated with female gender (OR: 2.7, P  = .017). Conclusions: Not any UAS use but a higher caliber UAS use may improve SFR and protect against AKI after RIRS. Although UAS insertion failure is seen mostly in men, it may be more challenging in women owing to less efficacy of preoperative Double-J stent.