Previous studies have suggested that urine cytology adequacy may be related to both specimen volume and cellularity.
The authors reviewed cytospin preparations from 314 urine specimens (162 voided and 152 instrumented specimens) found to have high-grade urothelial carcinoma on biopsy.
The sensitivity of instrumented urine cytology was significantly higher than that of voided cytology (82% vs 25%; P < .001). The cellularity (at least 30 urothelial cells/10 high-power fields [HPF]) of instrumented urine specimens also was significantly higher than that of voided specimens (57% vs 9%; P < .001). The sensitivity of voided urine cytology with a cellularity of 20 to 39 cells per 10 HPF was significantly higher than that of cases with <20 cells per 10 HPF (77% vs 19%; P < .001). The sensitivity decreased with higher cellularity for both types of specimens. The sensitivity of voided cases with a volume of at least 30 mL was higher than that of cases with a volume <30 mL, but this was not statistically significant (31% vs 17%; P = .07).
The sensitivity of voided urine cytology for high-grade urothelial carcinoma is significantly associated with urothelial cellularity but not specimen volume. Both the cellularity and sensitivity of voided urine specimens are less than that of instrumented specimens.