- Design
- Prospective randomised controlled study
- Population
- 185 patients with infectious upper urinary tract stones; 93 flexible negative-suction sheath, 92 traditional access sheath
- Primary outcome
- Stone-free rate on the first postoperative day
- Effect
- Higher stone-free rate at day 1 and 30 days (both P<0.05); lower WBC, CRP and procalcitonin at 6 and 24 hours (all P<0.05); shorter operative time and stay (P<0.001); lower overall complication rate (P<0.05)
Operating on an infected stone means accepting that irrigation raises intrarenal pressure and pushes bacteria and endotoxin into the circulation. A flexible negative-suction ureteral access sheath is designed to evacuate fragments and irrigant continuously, keeping that pressure down.
This prospective randomised trial enrolled 185 patients with infectious upper urinary tract stones — 93 to the suction sheath, 92 to a traditional access sheath — with stone-free rate on the first postoperative day as the primary outcome.
Stone-free rates were significantly higher in the suction group both at day one and at 30 days. White cell count, C-reactive protein and procalcitonin were all lower at 6 and 24 hours after surgery. Operative time was shorter, hospital stay was shorter, and quality of life improvement was greater (all P<0.001). The overall complication rate was lower. Ureteral stricture at three months occurred in three traditional-sheath patients and one suction-sheath patient, a difference too small to be significant.
The inflammatory markers are the part that distinguishes this from a stone-clearance study. Lower procalcitonin at six hours is consistent with less bacterial translocation during the case, which is the mechanism the device is meant to address — and infected stone surgery is where urosepsis actually happens.
- The value is in the infected stone, where intrarenal pressure translates into sepsis risk
- Procalcitonin and CRP at 6 and 24 hours are the markers that track the mechanism
- Higher stone-free rate at day one and at 30 days — the benefit was not just early clearance
- Cost and availability decide whether this is usable; the sheath is a consumable
- Stricture rates were not different, but four events cannot rule out a difference
Why it matters
It targets the specific mechanism by which infected stone surgery becomes urosepsis, and shows the markers moving.
Don't overread it
Single-study evidence with P values reported in place of effect sizes; the stricture comparison is underpowered.
The statistics, in plain English
The trial reports P values without effect sizes for most outcomes, so we know the differences were unlikely to be chance but not how large they were — that is a real limitation in reading this. The stricture comparison (3 versus 1) is the clearest example: with four events in 185 patients, the study had no ability to detect a difference either way, and 'not statistically significant' here means 'not measured', not 'no difference'.
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