Improving the Detection of Urine Sediment with a Modified Urinalysis Review Procedure

Currently, numerous review procedures are applied to perform the urine sediment examination. Clinical technologists and nephrologists use different procedures for the determination of specimen concentration and for particle counting. These techniques may underestimate the formed elements such as pathological casts (CASTs) and renal tubular epithelial (RTE) cells and might interfere with clinical diagnosis. The aim of this study was to evaluate a modified review procedure for urinary analysis and to narrow the gap between nephrologists and technologists by increasing the detection positivity rate for pathological formed elements.

We implemented a modified urinalysis procedure between October 2016 and January 2017 based on strict manual microscopic criteria and the currently available equipment. We confirmed the agreement between methods using a review procedure and Sysmex UF-1000i urinary flow cytometer (Pairwise Agreement > 0.88 for WBCs, RBCs, CASTs, and SRCs). Then we derived the review procedure that was based on the optimal sensitivity and specificity as follows: RBC > 26.1/µL, WBC > 37.0/µL, CAST > 1.0/µL, SRC > 8.2/µL, XTAL > 1.5/µL, YLC > 10.0/µL, BACT > 287.5/µL.

Of the 317 specimens investigated, 17.4% (26/149) and 31.5% (39/124) of the specimens for RTEs and Path. CASTs, respectively, were correctly detected using the proposed review procedure. Sensitivity and specificity for this procedure was 96.9% and 46.2%, respectively. In addition, we verified the ability of the procedure to detect the pathological elements with technologists and nephrologists and the agreement was satisfactory.

This modified review procedure can significantly improve the quality of urinalysis and reduce the risk of underestimating the detection of pathological particles.