The Paris System for Reporting Urinary Cytology reduces atypia rates and does not alter the negative predictive value of urine cytology.

Introduction: The Paris System for Reporting Urinary Cytology (TPS) was developed for standardization purposes and it placed an emphasis on screening for high-grade urothelial carcinoma (HGUC). Since then, it has shown to reduce atypia rates and better correlate with surgical specimens. The aim of this study was to calculate the negative predictive value (NPV) of urinary cytology for detecting HGUC using TPS and compare these data to our recently published pre-TPS cohort. As a screening test, it is imperative that TPS has a high NPV.

Material And Methods: A search of our institution's pathology database for the term "negative for HGUC" from January 1, 2016, to December 31, 2017, was conducted. A true negative was defined as a patient with at least 1 subsequent negative urine cytology/surgical biopsy specimen or the patient being clinically negative for 6 months. NPV rates were calculated based on the data obtained.

Results: The cohort consisted of 2960 urine cytology specimens from 1894 patients. A total of 99 false negatives were identified, generating a NPV of 96.7% (2861/2960). This NPV is identical to our previously published pre-TPS cohort (years 2012-2013; NPV: 96.7%). The clinical indication most effected NPV, with a history of urothelial carcinoma with a NPV of 93.9% followed by hematuria at 98.9%. The atypia rate in years 2012-2013 was 8.2% and in 2016-2017 it was 5.7% (P < 0.001).

Conclusions: We demonstrate that TPS did not alter the NPV for detecting HGUC compared to our pre-TPS cohort. We believe that TPS is an effective reporting system for screening HGUC in urinary cytology.