Purpose: To characterize microstructural and mechanical heterogeneity in calcium oxalate monohydrate (COM) renal calculi using high-resolution Vickers microhardness testing, and to explore potential implications for laser lithotripsy outcomes. Materials and Methods: Five highly selected COM stones retrieved during flexible ureteroscopy. Composition was confirmed by FTIR spectroscopy. Each specimen underwent a technically demanding preparation protocol, including embedding, high-precision polishing, light microscopy, and high-resolution Vickers microhardness mapping in collaboration with a university materials science laboratory. Results: Stone diameters ranged from 1.5–3 mm. Vickers hardness varied widely (45–180 HV0.2), with mean per-stone values between 76.2 and 137.5 HV0.2. All stones exhibited alternating hard and soft regions without concentric or radial patterns. Conclusions: COM stones demonstrate pronounced, irregular microhardness variation. This heterogeneity may explain why some regions dust easily while others resist laser ablation and persist as fragments. Mechanical profiling may serve as a useful adjunct in planning endourological stone treatment.
Heidler et al. (Mon,) studied this question.