Computed tomography-based mapping of ureteral stone distributions by anatomical segment and vertebral level

Classical anatomical teaching describes three ureteral narrowing points as the principal sites associated with ureteral stone localization; however, contemporary imaging studies suggest a more complex distribution. This retrospective study aimed to characterize ureteral stone distributions using detailed vertebral-level mapping complemented by conventional segmental classification and multiplanar stone measurements. Non-contrast computed tomography (CT) images of 398 patients, each contributing a single ureteral stone, were subjected to analysis. Stones were classified according to five anatomical ureteral segments and detailed vertebral levels. Vertical, transverse, sagittal, and maximum stone diameters were measured. The proximal ureter was the most frequent stone location (34.4%), followed by the ureteropelvic junction (UPJ; 26.1%) and ureterovesical junction (19.8%). Vertebral-level mapping demonstrated distinct clustering: UPJ stones were most frequently located at the upper third of L3 (25.0%), whereas proximal ureteral stones clustered predominantly around L3-L4, with the highest proportion at the lower third of L4 (21.9%). Stone dimensions differed significantly across the ureteral segments (p < 0.001 for all), the largest dimensions being observed at the UPJ and an overall tendency toward smaller dimensions at more distal locations. These findings demonstrate that ureteral stone distributions at CT presentation are not confined to the traditionally described narrowing points. Detailed vertebral-level mapping provides a more granular topographic characterization of stone localization than conventional segmental classification and may serve as a standardized anatomical framework for future studies.