[Evidence of improved quality of urinary calculus analysis using results of 7 surveys with external quality controls. Improvement in the quality of urinary calculus analysis by establishment of uniform methodological assumptions in urinary calculus analysis laboratories. 2].

Seven quality control surveys confirmed the usefulness of standardized urolith analysis by X-ray diffraction. A method is suggested for tabulating the results of the surveys, which permits qualitative comparison of participating analysis centres. Quality improved considerably after the introduction of the standardized instructions for analysis. The results of the survey with international participants clearly demonstrated the superiority of X-ray diffractometric urolith analysis over polarization microscopical, infrared spectroscopic, differential thermoanalytical and wet chemical analytical techniques.