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• UriSed 3 PRO was tested for bacteriuria screening with 56 426 regional samples. • The sensitivity reached was 87–92% with a NPV 90–96% depending on criteria. • Preanalytical detail on bladder incubation time would improve NPV. • Economy of screening depends on costs and specificity against urine cultures. • Complexity of regional health-care guides adaptation of screening processes. We assessed the possibility to rule out negative urine cultures by counting with UriSed 3 PRO (77 Elektronika, Hungary) at Helsinki and Uusimaa Hospital District. Bacteria counting of the UriSed 3 PRO automated microscope was verified with reference phase contrast microscopy against growth in culture. After acceptance into routine, results of bacteria and leukocyte counting from 56 426 specimens with eight UriSed 3 PRO instruments were compared against results from parallel samples cultured on chromogenic agar. Laboratory data including preanalytical details were accessed through the regional database of the Helsinki and Uusimaa Hospital District. A combined sensitivity of 87–92% and a negative predictive value of 90–96% with a specificity of 54–50% was reached, depending on criteria. Preanalytical data (incubation time in bladder) combined with the way of urine collection would improve these figures if reliable. Complex patient populations, regional logistics and data interfases, and economics related to increased costs of additional particle counts against costs of screening cultures of all samples, did not support adaptation of a screening process of urine cultures. This conclusion was made locally, and may not be valid elsewhere. [ABSTRACT FROM AUTHOR]

• UriSed 3 PRO automated microscope was successfully verified for nine laboratories. • Uncertainties were estimated for imprecision and comparisons of low particle counts. • New autoverification rules managed 70–75% of samples using 10 instruments. Ten UriSed 3 PRO automated microscopes (77 Elektronika, Hungary) were verified for nine HUSLAB laboratories with 160 000 annual urine samples. Particle counting of the primary UriSed 3 PRO instrument (77 Elektronika, Hungary) was verified against reference visual microscopy with 463 urine specimens, and against urine culture on chromogenic agar plates with parallel 396 specimens. Nine secondary instruments were compared pairwise with the primary instrument. Relative imprecisions compared to Poisson distribution, R(CV), were estimated to be 1.0 for white blood cell (WBC) and 1.5 for red blood cell (RBC) counts, respectively. Spearman's correlations against visual microscopy were r S = 0.94 for WBC, r S = 0.87 for RBC, and r S = 0.82 for squamous epithelial cell (SEC) counts. Agreement with visual microscopy (Cohen's weighted kappa) was 0.94 for WBC, 0.89 for RBC, 0.88 for SEC, 0.59 for combined casts, and 0.49 for non-squamous epithelial cells (NEC). Bacteria were detected with a sensitivity of 90% and specificity of 39 against culture at 107 CFB/L (104 CFU/mL). Created flagging limits allowed automated reporting for 70–75% of patient results. UriSed 3 PRO instruments were adopted into routine use after acceptance of the verification. [ABSTRACT FROM AUTHOR]