Clinical and cytopathological factors affecting the cellularity of urinary cell blocks and the implication for diagnosis and follow-up of urinary bladder urothelial carcinoma

Objective: The methodology of cell blocks (CBs) has long been an integrated part of cytology. However, there are very few data on CBs derived from urine. Their main disadvantage is a lack of cellularity, which limits their broader clinical applicability. Factors affecting cellular adequacy in urine remain unclear. We assessed the impact of basic clinical and cytopathological factors on the adequacy of cellularity in urinary CBs.

Methods: Freshly voided urine was collected from 401 consecutive individuals. Of these, 167 patients were diagnosed with urothelial carcinoma. The remaining 234 patients had various benign urological conditions. Papanicolaou classes were determined and CBs produced. Cellular adequacy was assigned to each CB (acellular, hypocellular, moderate cellularity, high cellularity), and moderately and highly cellular CBs were considered as adequate. Several factors were analysed to find any correlation with the adequacy of the cellularity.

Results: In univariate analysis, seven factors significantly correlated with the adequacy of the CBs. In the multivariate model, positive sediment (OR = 3.7), female sex (OR = 2.7), positive urinary cytology (OR = 2.6) and positive leucocyturia (OR = 2.1) were independent predictors of adequate cellularity. Positive predictive value and negative predictive value of the model were 65.0% and 77.7%, respectively.

Conclusions: We determined four clinical and cytopathological factors which independently predict adequate cellularity in urinary CBs. Based on these results, several clinical situations have been proposed, in which the highest probability of adequate cellularity in urinary CBs can be achieved.