Microscopic estimation of bacteria and cells in urine. I. Theoretical considerations

The present paper describes theoretical considerations how urine samples should be microscoped so that "cells/particles per microscope field" well correlate to "cells/particles per cm3". Within the method described here, significant bacteriuria should be easily found and contaminations (below 10(4) bacteria per cm3) would not be visible. Theoretically the method is suitable for microscoping bacteria, white cells, erythrocytes, epithelial cells and cylinders. The calculations presented indicate the importance of quality control in microscoping urine samples, and can explain the differences between the results obtained in different laboratories.