Urine sediment examination: a comparison of automated urinalysis systems and manual microscopy

Abstract

Background: Several automated instruments examining urine sediment have been introduced. We compared the performance of Sysmex UF-100 and Iris iQ200 with manual microscopy in urine sediment testing.

Methods: Four hundred and thirty-six urine samples were collected. The urine sediments were examined by manual microscopy and these 2 automated urinalysis systems.

Results: The within-run CVs for urine samples ranged from 3.4% to 22.3% for the iQ200, 1.6% to 24.2% for the UF-100 and 12.5% to 43.9% for manual microscopy. Between-run CVs on quality-control samples ranged from 6.1% to 32.4% for the iQ200 and 3.5% to 24.7% for the UF-100. The agreement between methods was good for red blood cells and white blood cells counts based on r values of 0.935 to 0.968. However, for epithelial cells, the values measured by different systems were poorly correlated (r=0.888-0.922). The Bland-Altman plot indicated a trend towards the automated cell count being greater than the manual microscopy as the epithelial cell count increased. Casts were difficulty differentiated by 2 automated systems.

Conclusions: These 2 automated urinalysis systems demonstrated good concordance with each other in urine sediment examination. The automated process could be used as a screening procedure but some manual microscopy was still necessary.