Internal quality control of the urinary sediment light microscopy using home-brew control materials

Since there is wide interobserver variabilities in microscopic urinary sediment evaluation, quality control programs for urinary sediment test using control materials are warranted in Japan. We performed internal quality control using home-brew control materials and cross-checking of urinary sediment tests by the three technologists including two experts and one newcomer. Variabilities among the three technologists in counting red blood cell (RBC), white blood cell (WBC), and casts were found to be improved as early as five days after the start of quality control particularly in the newcomer. Half a year later, coefficients of variation of the three technologists in counting these components were all about ten percent, which were lower than those observed in the initial examination. In the cross-checking of urinary sediments, more than 93% of the results of RBC and WBC and 84% of the results casts were reported within one lank difference. The rare components including waxy cast, atypical cell, dysmorphic RBC, Trichomonas vaginalis were detected similarly by the three technologists. Thus, internal quality control of urinary sediment tests using home-brew control materials and cross-checking among medical technologists is useful for standardization of urinary sediment tests and training of a newcomer in a clinical laboratory.