Endourologists continually strive to maximize stone clearance while curbing infectious complications during retrograde intrarenal surgery (RIRS). While conventional ureteral access sheaths facilitate instrument passage, they rely entirely on passive irrigation outflow. Consequently, high intrarenal pressure during prolonged lithotripsy can provoke pyelovenous backflow and systemic bacteremia. To address this persistent challenge, innovators developed suction ureteral access sheaths that actively evacuate irrigation fluid and pulverized gravel. A newly updated systematic review and meta-analysis of 29 comparative studies comprising 5,604 patients now provides decisive clinical insights. This study rigorously evaluates whether active suction mechanisms and specific sheath tip designs enhance stone clearance and perioperative patient safety.

Core Findings on Stone Clearance and Residual Fragments

Achieving complete stone clearance represents the benchmark of successful endourological intervention. In this comprehensive meta-analysis, suction sheaths significantly decreased residual fragments across both early and late assessment intervals. Specifically, investigators evaluated early clearance within three weeks post-surgery across 22 comparative studies. Patients treated with active suction demonstrated a 51% relative reduction in early residual fragments compared to traditional sheaths. Furthermore, this stone-clearing benefit persisted into late radiological follow-up at four weeks or beyond across 23 studies. At this late milestone, suction technology achieved a 47% relative reduction in persistent fragments. Continuous fluid evacuation constantly aspirates particulate dust during laser lithotripsy. Consequently, the operating surgeon maintains an unobstructed visual field without performing repetitive basket extractions. This streamlined mechanism prevents stone dust from settling into dependent calyces, thereby lowering the probability of post-procedural colic and secondary surgical procedures.

Suction Ureteral Access Sheaths and Infectious Complications

Infectious complications present substantial clinical hazards during endoscopic renal surgery. Traditional sheaths often fail to prevent rapid elevations in intrarenal pressure when irrigation rates rise. In contrast, suction ureteral access sheaths maintain a continuous negative pressure gradient that safely drains irrigation fluid. The meta-analysis revealed that active suction sheaths cut the incidence of postoperative fever by more than half. Furthermore, the risk of overt postoperative sepsis decreased by 53% compared to conventional sheaths. The pooled risk ratio for severe systemic complications also dropped to 0.48, demonstrating notable protection. Septic shock occurred infrequently across both cohorts, totaling 4 events in suction cases versus 12 in control cases. Although this shock reduction favored suction, the finding did not achieve statistical significance. Nonetheless, lowering febrile episodes and systemic sepsis proves clinically meaningful, especially in patients with colonized urine or large stone burdens.

Evaluating Tip Flexibility: Navigable Versus Fixed Sheath Designs

A central question in modern endourology centers on sheath tip engineering. Fixed-tip suction sheaths remain stationary in the proximal ureter or renal pelvis. Conversely, flexible and navigable suction ureteral access sheaths (FANS) deflect directly into targeted calyces alongside the flexible ureteroscope. Post hoc subgroup analyses within the meta-analysis revealed that tip design significantly modifies late stone-free outcomes. Specifically, patients treated with tip-flexible sheaths experienced a superior reduction in late residual fragments, achieving a risk ratio of 0.47. In contrast, fixed-tip sheaths achieved a more modest risk ratio of 0.72, and this difference reached statistical significance. Navigable sheaths bring the suction lumen directly to dependent anatomical niches, such as lower-pole calyces. Consequently, surgeons can evacuate heavy stone debris at the exact point of laser disintegration. However, because observational studies largely drove this finding, dedicated randomized controlled trials must confirm whether flexible tips justify higher device costs.

Operative Efficiency and Length of Hospitalization

Clinical teams frequently adopt new surgical technology to shorten operating times and accelerate patient recovery. Intuitively, active stone evacuation should reduce time-consuming basket retrieval during lithotripsy. However, the meta-analysis revealed no statistically significant difference in operative duration between suction sheaths and traditional sheaths. Setting up suction tubing, regulating pressure dials, and maneuvering steerable sheaths likely offset gains in fragment evacuation speed. In addition, the researchers analyzed post-procedural length of hospital stay across eligible trials. Patients receiving suction sheaths experienced a slight reduction in hospital stay of 0.32 days. Nevertheless, sensitivity analyses indicated that this modest difference lacked statistical robustness across centers. Hospital discharge practices vary widely based on local protocols rather than purely physiological recovery markers. Thus, while suction access does not dramatically compress procedure times, it establishes a clearer surgical field and reduces surgeon fatigue throughout complex intrarenal cases.

Evidence Certainty and Clinical Translation Under the GRADE Framework

Translating meta-analytic conclusions into institutional protocols requires a careful appraisal of methodological quality. Using the GRADE framework, the study authors assigned moderate certainty to evidence regarding stone clearance and postoperative fever reduction. These endpoints demonstrated consistent effects across numerous cohorts, supporting reliable clinical adoption. In contrast, the certainty of evidence for early stone clearance in non-randomized studies remained low due to potential confounding. Similarly, researchers graded the evidence for sepsis, septic shock, and severe complications as low or very low certainty. Only four of the twenty-nine included studies were randomized controlled trials, which limits overall certainty. Furthermore, variable definitions of stone-free status and differing suction pressures introduced between-study heterogeneity. Despite these methodological limitations, the physiological benefits of low intrarenal pressure remain undeniable. Endourologists can confidently deploy suction sheaths in high-risk patients while awaiting further confirmatory randomized trials to standardize specific suction parameters.

Frequently Asked Questions

How do suction ureteral access sheaths improve stone-free rates during RIRS?

Suction ureteral access sheaths establish a continuous negative pressure gradient within the renal collecting system during laser lithotripsy. Consequently, the fluid current immediately vacuums pulverized stone fragments and dust through the sheath lumen. This continuous evacuation prevents debris accumulation in dependent lower-pole calyces, eliminates the need for repetitive basket retrievals, and significantly improves endoscopic visibility. As a result, surgeons achieve higher stone clearance rates and drastically reduce residual stone burden at postoperative follow-up.

Why does suction reduce postoperative fever and infectious complications?

Traditional ureteral access sheaths rely solely on passive fluid outflow, which frequently causes intrarenal pressures to spike above critical thresholds. Such pressure spikes trigger pyelovenous backflow, forcing bacteria and endotoxins directly into systemic circulation. In contrast, suction ureteral access sheaths continuously aspirate irrigation fluid, maintaining safe intrarenal pressures throughout the entire procedure. Therefore, this active fluid regulation drastically mitigates bacterial translocation, significantly lowering the incidence of postoperative systemic inflammatory response syndrome, fever, and urosepsis.

What advantage do flexible and navigable suction sheaths offer over fixed-tip designs?

Flexible and navigable suction sheaths allow endourologists to deflect the distal sheath tip directly into specific renal calyces. This active deflection provides direct suction at the exact site of stone fragmentation, which fixed-tip sheaths stationed in the upper ureter cannot achieve. Consequently, navigable sheaths effectively evacuate dependent lower-pole calculi with greater precision. Meta-analytic data indicate that flexible-tip sheaths yield significantly lower late residual fragment rates compared to conventional fixed-tip configurations in retrograde intrarenal surgery.

Disclaimer: This content is for informational and educational purposes only, and does not substitute professional medical advice, diagnosis, or treatment. Healthcare professionals must exercise independent clinical judgment. Refer to the latest local and national guidelines for clinical practice.

References

1. Shiomi da Cruz JA et al. Suction versus traditional ureteral access sheaths in retrograde intrarenal surgery: an updated systematic review and meta-analysis of stone-free rates and complications. World J Urol. 2026 Nov 05. doi: undefined. PMID: 42986335.
2. Gonçalves FGA, Porto BC, Terada BD, et al. Enhanced stone-free rates with suctioning ureteral access sheath vs traditional sheath in retrograde intrarenal surgery: a systematic review and meta-analysis. BMC Urol. 2025;25(1):86.
3. Kayano S, Matsukawa A, Laukhtina E, et al. Impact of suction ureteral access sheath in ureteroscopy/retrograde intrarenal surgery: a systematic review and meta-analysis. Transl Androl Urol. 2025;14(5):1120-1131.