In 2020, external quality assessment trials for urinalysis and fecal occult blood (FOB) testing were conducted using data from 1,696 participants. Urine chemistry tests were performed three times, and urine sediment and FOB tests were performed twice. Urine chemistry tests consisted of pH, protein, glucose, ketone bodies, bilirubin, blood, urobilinogen, nitrite, leukocyte, and specific gravity analyses. The results of urine chemistry and specific gravity tests showed acceptable rates of >95%, except for the pH, bilirubin, and urobilinogen tests; however, with some instruments, the acceptable rates of pH, ketone, bilirubin, protein, and urobilinogen tests were <50%, suggesting matrix effects of quality control materials. The acceptable rates of urine sediment analyses were low, especially for renal tubular epithelial cells, waxy and broad casts, and calcium oxalate crystals. In contrast, the acceptable rates for uric acid crystals, squamous epithelial cells, and ammonium biurate crystals were high. In the FOB quality test, five reagents showed acceptable rates of <90% for the negative samples, indicating the possibility of false positives. In the FOB quantitative test, the Alfresa NS-Plus C instrument showed high values in negative specimens; based on the 2019 results, its usage has now declined.

Keywords: Quality control, Urinalysis, Occult blood, Accuracy