Suction Sheath Use Raised Stone-Free Rates in High-Risk Ureteroscopy
Flexible ureteroscopy in the setting of an initially positive preoperative urine culture sits at the edge of surgical caution. Bacteria may persist in the collecting system even after antimicrobial treatment, and irrigation during endoscopy can force contaminated fluid under pressure into the bloodstream or renal parenchyma. In that setting, any device that lowers intrarenal pressure while improving fragment clearance has immediate clinical appeal.
A retrospective matched analysis now links flexible negative-pressure suction ureteral access sheath use with better operative and infectious outcomes in adults undergoing flexible ureteroscopy for renal stones after a positive urine culture had been cleared before surgery. Adults treated between August 2022 and August 2025 were screened, and after the suction sheath entered practice in January 2024, concurrent cases were matched 1:1 by surgeon and calendar half-year. The final cohort included 173 matched pairs.
The surgical pathway was already cautious. Patients received susceptibility-guided antimicrobial therapy and proceeded only after a negative repeat urine culture. Even with that preparation, the physiology of endoscopic stone treatment still leaves room for trouble, because irrigation pressure can climb quickly during inspection, basket work, and dusting. The suction sheath was designed to counter that problem by actively evacuating irrigation fluid and stone debris instead of letting pressure accumulate inside the kidney.
Lower Pressure, Better Clearance, Fewer Complications
The primary endpoint was single-session stone-free status, defined as residual fragments 3 mm or smaller on 1-month noncontrast CT. In the matched cohort, single-session stone-free status was higher with suction sheath assistance: 89.0% versus 75.7%, a risk difference of 13.3 percentage points. Complete clearance also favored the suction approach, at 74.0% versus 59.0%.
Those gains are clinically meaningful because residual fragments often become the substrate for regrowth, recurrent infection, and repeat intervention. A one-session success rate closer to nine in ten changes the postoperative conversation at the bedside. It reduces the likelihood that a patient who already entered surgery with microbiologic risk will need another anesthetic and another infected collecting-system exposure.
Pressure data moved in the same direction. Mean intrarenal pressure, peak pressure, and time spent under high pressure were all lower in the suction sheath group, with every comparison reaching statistical significance. That matters mechanistically. Renal pelvic overpressure promotes pyelovenous and pyelolymphatic backflow, a route by which bacteria and endotoxin can escape the collecting system. Lowering pressure should therefore reduce the chance that a contaminated renal unit becomes a systemic infectious event during or after ureteroscopy.
Complications were less frequent as well: 15.0% with suction sheath use versus 26.6% without it, corresponding to a risk difference of -11.6 percentage points. After adjustment, the odds of complications were lower with suction, with an odds ratio of 0.46. Fever without sepsis occurred less often in the suction arm. Urosepsis and septic shock did not differ between groups, so the signal appears strongest for nonsevere infectious morbidity rather than the rarest catastrophic outcomes.
That pattern is important. It suggests the device may be helping most where pressure reduction and debris evacuation can interrupt the pathway from bacterial shedding to febrile postoperative illness, while leaving severe sepsis too infrequent in this dataset to separate cleanly between arms.
Culture Positivity Declined, but Causality Remains Unproven
The study also tracked culture positivity over time. Positivity declined in the suction group, and the average odds were lower with suction, with an odds ratio of 0.53. The group-by-time interaction was not significant, which limits how confidently the temporal trend can be attributed to the device alone. Even so, the direction of effect aligns with the rest of the physiologic data: less pressure, less contamination spillover, and fewer febrile complications.
Because this was a retrospective study, the design cannot eliminate all confounding. Propensity-score matching by surgeon and calendar half-year narrows some of the bias introduced by learning curves and practice drift, but it does not recreate the balance of a randomized trial. The cohort also came from a single center, which means local technique, antimicrobial policy, and postoperative surveillance may have shaped the outcome profile.
Even with those limits, the data fit a plausible mechanistic chain. When a suction sheath continuously evacuates irrigation fluid, it may limit intrarenal distension, improve visibility, and speed fragment extraction. Better visibility can reduce operative hesitancy, and lower collecting-system pressure can reduce the risk of backflow-driven infection. In a patient who started with a positive urine culture, even after culture clearance, that combination is exactly the kind of physiologic control urologists want during flexible ureteroscopy.
The authors concluded that suction-sheath use was associated with higher stone-free rates, lower pressure, and fewer complications, while also calling for confirmation in multicenter randomized trials. That next step is necessary because the present results are associative, not causal, and because the most feared outcomes—urosepsis and septic shock—were too uncommon to prove a difference with confidence.
For now, the practical message is narrow but relevant: in renal stone surgery performed after an initially positive urine culture, active suction may improve the balance between stone clearance and infectious safety, but only a randomized trial can determine whether the benefit holds across surgeons, institutions, and broader case mixes.