Adequacy of voided urine specimens prepared by ThinPrep and evaluated using The Paris System for Reporting Urinary Cytology

Introduction The Paris System for Reporting Urinary Cytology (TPS) currently includes a volume recommendation for voided urine specimens of 30 mL based on observations of performance with BD SurePath preparation system. Given that many labs use the Hologic ThinPrep methods for voided urines, an analysis of data acquired with this system is undertaken in this study. Materials and methods We identified a total of 744 voided urine specimens. All specimens were processed fresh by ThinPrep at a large academic center that had incorporated a tiered urine cytology reporting template prior to TPS. To determine the optimum binary cutoff thresholds for voided urine volume, the fraction of high-risk cytologic diagnoses—suspicious for high-grade urothelial carcinoma (SHGUC) or worse—was compared below and above various volumes cutpoints. Results The cytology diagnosis was inadequate in 1.5%, negative for high-grade urothelial carcinoma in 64%, atypical urothelial cells in 14.2% SHGUC in 6.6%, high-grade urothelial carcinoma (HGUC) in 11.3%, low-grade urothelial neoplasm in 1.9%, and other malignancies in 0.5%. High-risk cytology was diagnosed in 19.1% of specimens ≥25 mL and in 13.5% of specimens P = 0.090). Volume of ≥25 mL was associated with the optimum cutoff for diagnosing SHGUC or HGUC. Conclusions A specimen volume of ≥25 mL is associated with higher rates of diagnosis of HGUC or SHGUC in voided urine specimens processed by ThinPrep. This is similar to the 30 mL cutoff determined for SurePath preparation that was incorporated into TPS and may provide helpful information for ThinPrep labs that are in the process of adopting TPS.