Implementation of the Paris System for Reporting Urinary Cytology results in lower atypical diagnostic rates

The Paris System for Reporting Urinary Cytology (PSRUC) provides a standardized reporting schema for urine cytology with defined criteria for each diagnostic category. We report the impact at our institution of adopting the PSRUC on the frequency and distribution of urine cytology diagnoses, with particular attention to the "atypical" category as it serves as a potential laboratory quality control measure.

Urine cytology specimen diagnoses were evaluated during 5-month periods prior to and after the introduction of PSRUC. The number of cases in each diagnostic category by either the laboratory as a whole or by individual cytopathologists were analyzed. Following confidential feedback given to individual cytopathologists, a third 5-month period of cytology diagnosis analysis was performed.

The overall laboratory atypical call rate was significantly lower in the post-PSRUC as compared with the pre-PSRUC period (29.5% versus 21.8%; P < 0.0001), with individual cytopathologist atypical call rate lower post-PSRUC (range: 10.2%-37.9%) compared with pre-PSRUC (range: 12.2%-45.0%). The institution of feedback based on these findings did not result in any further statistical change in the atypical call rate (21.8% versus 22.2%).

Adoption of PSRUC resulted in a significant decrease in the number of atypical diagnoses with little change in the suspicious or malignant categories. Future studies are needed to determine the effect of decreased atypical call rates on the sensitivity/specificity of urine cytopathology, as well as to see if other measures (such as continued cytopathologist feedback or educational modules) can further reduce atypical rates.