Stone-Free Status after Kidney Stone Removal and the Need for Refined and Consistent Reporting

The rapid advancement of ureteroscopic (URS) technologies and techniques in recent years has revolutionized urologic stone disease treatment. Patients with large stone burdens are now being offered minimally invasive URS procedures with excellent clearance of stone. With these new advancements, however, comes the challenge of how we define the success of each intervention. "Stone-free rate," which uses maximal stone length to quantify stone clearance, is the term most often associated with the measurement of stone clearance in the literature and appears frequently throughout both the American Urological Association and European Association of Urology guidelines. However, maximal stone length might be an oversimplification of a three-dimensional structure such as kidney stones. We aim to review the challenges associated with traditional metrics, new and alternative metrics introduced in recent literature, and future directions for improved reporting and standardization.