Guy’s stone score and S.T.O.N.E. nephrolithometry score as predictive tools for percutaneous nephrolithotomy outcome

Abstract

Percutaneous nephrolithotomy (PCNL) is a standard surgical modality for the management of renal calculi, and accurate preoperative prediction of surgical outcomes and complications is essential for optimizing patient care. This prospective observational study aimed to compare the predictive effectiveness of Guy’s Stone Score (GSS) and the S.T.O.N.E. Nephrolithometry Score in determining PCNL outcomes. The study was conducted in the Department of Urology, Bangabandhu Sheikh Mujib Medical University (BSMMU), from February 2023 to August 2024, and included 35 patients undergoing PCNL selected through purposive sampling. Preoperative evaluation involved intravenous urography and non-contrast CT KUB to calculate GSS and S.T.O.N.E. scores, followed by PCNL and assessment of perioperative complications and stone-free status at four weeks postoperatively. The mean age of participants was 38.14 ± 8.58 years, with a male predominance and more frequent left-sided stone involvement. Overall stone-free rate was 82.86%, with higher success in lower score categories for both systems; GSS Grade I and low-risk S.T.O.N.E. scores (4-5) achieved 100% stone-free rates, while higher grades and scores were associated with increased residual stones and complications (p