Comparison of two liquid preservatives for SurePath™ slides prepared from voided urine

Blood-rich gynecologic specimens can be problematic in the processing of liquid-based cytology. However, little is known about the influence of erythrocytes and protein on urine specimens. In addition, the SurePath™ system has two preservatives for non-gynecologic specimens. In this study, we compared the epithelial cell counts and cytomorphology obtained from CytoRich™ (CR) Red and CR Blue. A total of 98 voided urine samples were processed using both CR Red and CR Blue. We made an assessment of the epithelial cell counts, fixation, and staining quality, and backgrounds of both slides. Urine protein and urine erythrocyte counts were analyzed, and those data were compared with the epithelial cell counts in CR Red and CR Blue slides. Overall, epithelial cell counts were equivalent for both CR Red and CR Blue slides. However, in high-level proteinuria cases, the CR Red slides showed higher epithelial cell counts than the CR Blue slides. On the other hand, in microscopic hematuria cases, the CR Blue slides showed higher epithelial cell counts than the CR Red slides. We have found both CR Red and CR Blue to be available for urine cytology. However, it is important to note that CR Blue is inferior to CR Red in epithelial cell recovery rates in cases of high-level proteinuria.