Dual-Sheath Technique Linked to Fewer Residual Stones After Minimally Invasive Kidney Stone Surgery

Patients with complex kidney or ureteral stones who underwent minimally invasive percutaneous nephrolithotomy with a novel dual-sheath technique showed a significantly lower risk of residual stones than those treated with a conventional single peel-away sheath, according to a retrospective two-center study published in the European Journal of Medical Research. The dual-sheath approach combines a metal sheath with a peel-away sheath during the procedure, and the study reports it as a feasible and safe modification of the standard operation.

The retrospective study included 211 patients with complex renal or ureteral calculi who underwent minimally invasive percutaneous nephrolithotomy between January 2023 and December 2024. Of these, 123 were treated with the dual-sheath approach and 88 with a single peel-away sheath. All procedures were performed by experienced surgeons following a standardized protocol. Because patients were not randomly assigned to the two techniques, the researchers applied propensity score matching to balance baseline characteristics between the groups before comparing outcomes.

At four weeks after surgery, the dual-sheath group showed a trend toward a higher stone-free rate, at 82.9 percent compared with 71.6 percent in the single-sheath group, but this difference did not reach statistical significance, with a P value of 0.072. The authors emphasize that this remains a non-significant trend rather than a demonstrated improvement in stone-free rates.

Where the two groups clearly diverged was in the rate of secondary interventions. Only 0.81 percent of patients in the dual-sheath group required a repeat procedure, compared with 12.5 percent in the single-sheath group, a difference the authors report as statistically significant with P less than 0.001. Postoperative complication rates, by contrast, showed no significant differences between the two groups, suggesting that the modified technique did not come at the cost of additional safety concerns in this cohort.

In this analysis, dual-sheath use was independently associated with a reduced risk of residual stones, with a hazard ratio of 0.47 and a 95 percent confidence interval of 0.25 to 0.88, corresponding to a P value of 0.019. The authors report that the results were consistent across sensitivity models, and Kaplan–Meier analysis with log-rank testing showed a significantly lower cumulative incidence of residual stones in the dual-sheath group, with a log-rank P value of 0.0063.

The dual-sheath method evaluated here uses a combined metal and peel-away sheath arrangement, which the authors describe as a novel approach aimed at improving outcomes in complex stone disease.

The study’s conclusion is deliberately measured. The authors state that the dual-sheath technique appears to be a feasible and safe modification of minimally invasive percutaneous nephrolithotomy for complex renal or ureteral calculi, that it is associated with a reduced risk of residual stones and fewer secondary interventions, and that a non-significant trend toward improved stone-free rates was observed. They explicitly call for further prospective multicenter studies to confirm these findings.

Several limitations follow from the study design. As a retrospective analysis of patients treated at two centers over a two-year period, the study cannot establish causation in the way a randomized trial would, and propensity score matching can only balance characteristics that were measured and recorded. The article was published as an accepted manuscript under Springer Nature’s early-access process, meaning it is citable and carries a permanent DOI but remains subject to further edits before the final version of record appears. Within those constraints, the reported hazard ratio and the marked difference in secondary intervention rates offer a concrete signal that the dual-sheath arrangement merits prospective testing in a broader patient population.

Subject of Research: A dual-sheath technique in minimally invasive percutaneous nephrolithotomy for complex renal or ureteral calculi

Article Title: A dual-sheath approach in minimally invasive percutaneous nephrolithotomy is associated with reduced residual stone risk: a two-center retrospective study

Article References: Jiang, C., Li, Q., Li, J., Wang, E., Shi, Y., Wang, P., Chen, Y., Wang, Y., Han, D., Liu, H., Ke, C., & Xiao, M. (2026). A dual-sheath approach in minimally invasive percutaneous nephrolithotomy is associated with reduced residual stone risk: a two-center retrospective study. European Journal of Medical Research. https://doi.org/10.1186/s40001-026-05340-6

Image Credits: AI Generated

DOI: 10.1186/s40001-026-05340-6

Keywords: percutaneous nephrolithotomy, kidney stones, residual stones, dual-sheath technique, urology, retrospective study, propensity score matching, stone-free rate, secondary intervention, minimally invasive surgery, dual-sheath, approach