Stone volume instead of maximum stone diameter: results from an international survey.

Objectives: To evaluate Urologists' perception regarding stone volume (SV) to assess the stone burden in current practice. Whilst SV might be considered as the most accurate measure of stone burden, international guidelines are to date based on maximum stone diameter (MSD).

Subjects and methods: An on-line survey (four parts, 22 multiple choice questions) designed by international Endourology experts was submitted to the urological community between December 2023 and January 2024. In addition to questions on clinical practice, stone burden reporting and lithotripsy methods, participants were asked to intuitively estimate the spherical SV equivalent of several stone sizes and situations. Interest in SV overall, including knowledge about SV measurement tools were also investigated.

Results: A total of 218 participants completed the survey, of whom 83% were male and 43% were aged 30-40 years. Approximately two thirds were European (63%), consultant Urologists (66%) and worked in a university hospital (66%). In all, 79% had specialist Endourology training and 44% declared more than half of their surgical activity was dedicated to Endourology. Although MSD was preferred to SV (67% vs 3%) for preoperative stone burden estimation, 64% of respondents were 'very keen' to have a tool to provide SV in future. The rate of correct intuitive SV estimations decreased with case complexity (from 40% to 20%). Endourology experts and academic Urologists were keener to adopt SV in practice but their ability to estimate SV was similar to those who were not Endourology trained or in non-academic posts.

Conclusions: Urologists agree that SV provides a better estimation for stone burden than MSD. However, intuitive SV estimation based on stone diameters seems insufficient, hence readily accessible SV estimation tools are warranted for using SV in routine practice.