Intrarenal Calculi

Abstract

In 2000, the ureteral access sheath was introduced to the urologic practice, facilitating multiple ureteral and renal reentries during flexible ureteroscopy (URS). The advent of this sheath and the evolution of flexible endoscopic technology ushered in a new paradigm of kidney stone surgery, giving urologists the ability to manipulate previously inaccessible lower pole or very large kidney stones while minimizing ureteral trauma during their removal. Retrograde flexible ureterorenoscopy with stone lithotripsy has now become a mainstream procedure in urology operating rooms across the world. This chapter analyzes the evidence-based data available for this procedure to aid in appropriate patient selection and prediction of stone-free rates (SFRs).

After appropriate study exclusion, we identified 18 published, peer-reviewed URS studies for treatment of renal stones, totaling 1,362 patients. Multiple retrospective case series and cohort studies were identified, but only 90 of the included patients (6.6 %) were the result of prospective series with SFR calculated by strict computed tomography (CT) criteria. For all stone sizes, SFRs were variable but ranged from 53 to 86 %. Due to the lack of uniformity in outcome reporting among all studies, these rates must be considered biased and unreliable for comparative purposes. Strict CT criteria lowered SFR by ∼30–40 %, demonstrating how SFR can be falsely elevated by using imaging modalities other than CT. Overall, the development and progression of ureteroscopic technology has made this modality a promising tool in the urologist’s armamentarium. However, the majority of reported renal success rates for URS in the literature are retrospective, biased, and based on non-standardized imaging and follow-up protocols. To clarify the efficacy of this modality, future URS trials should compare matched groups while measuring cost-effectiveness, validated postoperative quality of life and pain scores, and SFR by strict CT criteria. Only by careful study design can urologists increase patient satisfaction while optimizing patient outcomes.