The ureteral access sheath (UAS) has been a boon and a bane in flexible ureteroscopy (FURS), with its merits and demerits well established. Its design and dimensions were instrumental in reshaping the way flexible scopes were used and were key adjuncts to establishing retrograde intrarenal surgery (RIRS) as a standard of care in the endourological management of renal stones. With the ever-changing landscape of RIRS over the decades shaped by technological advancements in lasers and flexible scopes, the UAS has also continuously evolved. The utility of suction in endourology has recently changed the way RIRS is performed and is a game changer for FURS outcomes. With strong clinical and experimental evidence to support its use, the UAS has undergone a transformative change in the recent past, with its ability to monitor intrarenal pressure and provide a superior vacuum-cleaner effect that improves the trifecta of RIRS, namely an improved single-stage stone-free rate (SFR), minimise complications, and reduce reinterventions. Our comprehensive review outlines the key clinical and experimental evidence and traces the developments that were key to modifying the traditional UAS into a flexible and navigable suction ureteric access sheath (FANS) and highlights how the design and modifications, in turn, influence the ability to push the boundaries of RIRS.

Background: Technical advancements and intrarenal pressure are synergistic in improving perioperative outcomes during flexible ureteroscopy (FURS). Mismanaged intra-renal pressure (IRP) has negative consequences and it is associated with an increased risk of sepsis, bleeding, pelvicalyceal fluid extravasation, and even collecting system injuries and acute as well as chronic renal failure. The cornerstone of a safe FURS is the ability to continuously monitor IRP to avoid elevation of IRP above the normal range of 10 mmHg. Objectives: This scoping review aims to report the current state of real-time IRP monitoring in in vivo clinical studies and the various monitoring methods and technology to understand how this may be best used in daily clinical practice. Eligibility criteria: A systematic literature search was conducted. Only in vivo clinical studies published in English documenting IRP measurement methodologies during semirigid or flexible ureteroscopy for urolithiasis management were included. Results: Out of 1326 retrieved papers, 17 studies met the inclusion criteria, comprising 2 randomized controlled trials, 2 retrospective studies, and 13 observational studies. Current noninvasive IRP monitoring devices include ureteric catheters placed retrogradely or via percutaneous tubing and connected to pressure transducers, amplified by cardiology-used pressure sensing systems or urodynamic systems, automated pressure-regulating systems, pressure sensing guidewires, and IRP sensing flexible ureteroscopes. The review revealed significant variations in IRP measurement methods, reporting units, and irrigation techniques. Notably, elevated IRP above 30 mmHg was consistently associated with increased postoperative complications, including sepsis. Conclusion: Current clinical studies have only ascertained that increased IRP above 40 mmHg positively correlates with infectious complications and postoperative pain. No standardized values are available to predefine safe thresholds in practice. With the availability of noninvasive tools for IRP monitoring, future research should focus on multicenter studies to establish reference ranges and best practices for IRP management, ultimately improving patient outcomes in endourological procedures.