Urine sediment analysis: Analytical and diagnostic performance of sediMAX^® - A new automated microscopy image-based urine sediment analyser

Background: We evaluated the analytical and diagnostic performance of sediMAX (77 Elektronika, Budapest, Hungary), a new automated microscopy image-based urine sediment analyser (which in some countries is also called Urised) in comparison with visual phase-contrast microscopy. Methods: Precision, linearity, carry-over and method comparison were carried out according to well-established guidelines. The diagnostic performance with respect to visual phase-contrast microscopy was evaluated with results from two centres (n₁ = 910, n₂ = 1233). Uncentrifuged urine samples were used in visual microscopy in centre 1, while urine sediments were used in centre 2. Results: Within-run precision for RBC was 17.8% and 6.7% at 18 × E6 RBC/L and 447 × E6 RBC/L respectively and for WBC it was 17% and 4.4% at 4 × E6 WBC/L and 258 × E6/L respectively. Between-run imprecision for RBC was 14.7% for 30 × E6/L and 7.2% for 283 × E6/L. For WBC it was 5.4% at 25 × E6/L and 3% at 166 × E6/L. In both studies areas under ROC curves (AUC) were 80-90% for RBC, WBC, squamous epithelial cells, yeast and calcium-oxalate crystals. For non-squamous epithelial cells and pathological and hyaline casts the AUC ranged 73-74%. There was no carry-over. Conclusions: The sediMAX is well able to count and identify RBC, WBC, squamous epithelial cells, yeast, bacteria and calcium-oxalate crystals. Recognition of pathological casts and non-squamous epithelial cells is adequate but needs to be improved.