Evidence-based adequacy criteria for urinary bladder barbotage cytology

Adequacy criteria are well established in some areas of cytopathology to prevent false negative diagnoses. To date, no such criteria have been proposed and validated for urinary tract specimens. Our aim was to determine a cellularity cutoff point that significantly affects the sensitivity of detecting high-grade or in situ urothelial carcinoma (HGUC or UCIS) in bladder barbotage/washing specimens.

Bladder barbotage specimens collected in liquid-based media were selected. Specimens diagnosed as "positive for HGUC" (with histologic confirmation) composed the study group, with negative cases as control specimens. Samples were serially diluted and ThinPrep slides of decreasing cellularity were made and reviewed for diagnosis and cellularity. In a retrospective validation study, we identified cases with a "negative for malignancy" bladder barbotage/washing and a surgical pathology diagnosis of UCIS or HGUC (ie, false negative cytology). Cellularity was assessed.

A distinct difference in sensitivity was noted at a cutoff point of 2644 (20 per 10 high-power fields) urothelial cells. Sensitivities increased for atypical or higher (68.3% versus 100%) and HGUC (43.3% versus 88.0%) after application of this cutoff point with high statistical significance (P = 0.001 and 0.0001, respectively). For the retrospective review, cases below the cutoff point were reclassified as unsatisfactory, and sensitivity rose from 76.3% to 84.8% (P = 0.0027).

Our results indicate that, in the absence of atypical or malignant cells, an adequate bladder barbotage specimen should have a minimum of 2644 (20 per 10 high-power fields) well-visualized, well-preserved urothelial cells to increase the positive predictive value of this test.