Development of microscopic review criteria by comparison urine flow cytometer, strip and manual microscopic...

Microscopic examination is essential for urine analysis, but a time-consuming procedure. This study was undertaken to evaluate an automated urinalysis system - the Sysmex UF-1000i (URISYS 2400) for the analysis of urine constituents including chemistry components and particles. The objective was to screen urine samples and determine the screening criteria which would minimize the number of specimens reviewed with the microscope yet ensuring correct results.

A total of 1300 urine samples were sent for urinalysis using the automated system and compared with results obtained from manual microscopy using the Fuchs-Rosenthal counting chamber.

Using Pearson statistics, we observed correlation between the UF-1000i and manual microscopy: for red blood cells (RBCs) r was 0.949, for white blood cells (WBCs) r was 0.882, for epithelial cells (EC) r was less than 0.76, for casts r was less than 0.7, while correlation between the URISYS 2400 and manual microscopy: for red blood cells r was 0.772 and for white blood cells r was 0.771. With the help of Uriaccess (an expert system provided by the Sysmex Corporation), 37 rules for microscopic review were set up. The review rules were validated, the review rate was less than 30% and the false-positive and false-negative results were acceptably low.

UF-1000i is capable of reproducible measurement of urine particles within the clinically relevant range and shows its advantage over URISYS 2400. It is an optimal strategy for urine sample screening using the combination of the two methods.