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

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.

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).

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.

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.