Small- and large-calibre ureteroscopes: an updated systematic review and meta-analysis

Objective: To systematically review and meta-analyse the available evidence comparing perioperative outcomes between small- (≤6.3/7.5 F) and large-calibre (≥7.5/9.8 F) ureteroscopes. Methods: A literature search of MEDLINE/PubMed, and Scopus was performed prior to March 2026 according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The endpoints of interest were stone-free rates (SFRs), overall complications, and operative time. Study quality and risk of bias were evaluated using the Newcastle–Ottawa Scale and the Revised Cochrane Risk of Bias Tool for Randomised Trials for non-randomised and randomised studies. Sensitivity analyses were completed on studies reporting flexible ureteroscopes only, 7.5- vs >7.5-F ureteroscopes, and on randomised controlled trials (RCTs). Results: Eight studies were included in the meta-analysis. Of those, four were RCTs while four were retrospective. Specifically, three studies compared 6.3- vs 7.5-F ureteroscopes, one 6.3- vs 8.5-F ureteroscopes, one 6- vs 7.5-F ureteroscopes, while three compared 7.5- vs >7.5-F ureteroscopes. Within the meta-analysis comparing 6.3- vs 7.5-F ureteroscopes, the small-calibre ureteroscopes were associated with a risk ratio [RR] for SFR of 0.99 (95% confidence interval [CI] 0.92–1.06), of 1.08 (95% CI 0.77–1.51) for overall complications, and a standardised mean difference in operative time of −14.5 min (95% CI −33.4 to 3.3 min). These results were virtually confirmed by all sensitivity analyses. No differences in the above outcomes were recorded for the comparison between 7.5- vs >7.5-F ureteroscopes. Conclusions: Within the present meta-analysis, the small-calibre ureteroscopes achieved comparable outcomes to large-calibre ureteroscopes. To overcome the substantial heterogeneity and residual confounding across studies, well-designed and adequately powered RCTs are required. © 2026 BJU International.