Percutaneous Nephrolithotomy for Removal of Encrusted Ureteral Stents: A Multicenter Study
Bibliographic record
Abstract
PURPOSE: Encrusted ureteral stents are a challenging endourologic problem. We performed a multi-institutional review of percutaneous nephrolithotomy (PCNL) as primary treatment for encrusted stents. MATERIALS AND METHODS: We identified 36 patients who underwent PCNL for treatment of an encrusted stent. A retrospective review was performed to compile details of procedures and outcomes for these patients. RESULTS: In 36 patients, 38 renal units underwent PCNL for encrusted ureteral stents. The mean patient age was 47.1 years (±16.7), and the female:male ratio was 15:21. Mean stent indwelling time before removal was 28.2 months (±27.8). The reason for long indwelling time was reported in 25 cases; these reasons included "patient unaware stent needed to be removed" (17 cases), pregnancy (2 cases), other comorbidities (3 cases), and patient incarceration (3 cases). In 3 cases, the stent had become encrusted within 3 months of placement. Mean operative time was 162 minutes (±71). There were no major intraoperative complications, and no patients required blood transfusion. Litholapaxy was required for bladder coil encrustations in 22 cases (58%), and ureteroscopy with lithotripsy was required for encrustation of the ureteral portion of the stent in 13 cases (34.2%). Second look percutaneous procedures were required in 13 cases (34.2%). The stent was removed at the time of PCNL without need for concomitant or delayed ureteroscopy and/or cystolitholapaxy in 8 cases (21%). Ultimately, all stents were removed successfully. Patients were rendered stone free according to radiographs in 24 cases (63%). CONCLUSIONS: In this multicenter review, PCNL is confirmed to be a safe and effective means of addressing the retained and encrusted ureteral stent. PCNL without ureteroscopy or litholapaxy was sufficient in a minority of cases (21%). Adjunctive endourologic modalities are often required, and the surgeon should anticipate the need for concomitant antegrade ureteroscopic laser lithotripsy and/or cystolitholapaxy. Although complete stent removal can be anticipated, residual fragments are not uncommon.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".