Calcium oxalate stone morphology: fine tuning our therapeutic distinctions.

PURPOSE: We determined specific radiographic morphological patterns of crystallographically analyzed pure and mixed calcium oxalate dihydrate and calcium oxalate monohydrate urinary calculi.
MATERIALS AND METHODS: A total of 86 greater than 1 cm. calculi crystallographically analyzed as pure calcium oxalate monohydrate, calcium oxalate dihydrate or admixtures of the 2 types was studied to determine whether various forms of calcium oxalate differed in radiographic morphology.
RESULTS: Four distinct radiographic patterns could be identified by plain film roentgenography: group 1--14 patients with smooth edged, homogeneously dense calculi, some with dentate shapes (12 had pure calcium oxalate monohydrate stones), group 2--33 with multinodular calculi with irregular edges and variegated areas of more and less radiodensity (32 had greater than 60% calcium oxalate monohydrate), group 3--33 with a uniform, stippled pattern, often with identifiable radial striations, and with a larger amount of calcium oxalate dihydrate than groups 1 or 2, and group 4--6 with poorly radiodense, loosely aggregated crystals with a lacy structure.
CONCLUSIONS: At least 4 patterns of calcium oxalate stones are recognizable by plain film roentgenography. Because the fragility of calcium oxalate calculi is determined by the relative calcium oxalate monohydrate and dihydrate content, pretreatment recognition of these radiographic patterns may affect the selection of a therapeutic modality.