Outcome analysis and negative predictive value of the "unsatisfactory/nondiagnostic" category of The Paris System for Reporting Urinary Cytology.

Introduction: The Paris System (TPS) for Reporting Urinary Cytology (UCyto) was published in 2016, but to date, no study addressing the unsatisfactory (UNSAT) category has been published. We aimed to identify the negative predictive value (NPV) for UNSAT UCyto after the implementation of TPS at our institution.

Method: For the period from January 1, 2017, to December 31, 2019, we identified all cases with UNSAT diagnosis on UCyto specimens and available cytologic and/or surgical pathology follow-up within 6 months from the UNSAT diagnosis. Cases were deemed true negative (TN) if the follow-up was "negative for high-grade urothelial carcinoma" (NHGUC). Information regarding previous medical history, clinical indications, and specimen type were tabulated and analyzed.

Results: From 6348 UCyto specimens, there were 230 (3.6%) UNSAT diagnoses made on 209 patients (112 [53.6%] men and 97 [46.4%] women) with a median age of 64 years. Of these, 116 UCyto specimens from 106 patients, which had cytologic and/or surgical pathology follow-up within 6 months, were further studied. Most UNSAT UCyto specimens were bladder washing/barbotage (BW/BB), and the most common indication for UCyto was cancer surveillance. The main cause of UNSAT UCyto was low cellularity. There were 5 false-negative (FN) results for high-grade urothelial carcinoma (HGUC), which corresponds to an overall NPV of 84.4%. NPV was highest for patients with UCyto for hematuria, and for patients with BW/BB as UCyto specimen type.

Conclusions: Our results show that UNSAT diagnoses have a lower NPV than that typical of NHGUC diagnoses, and should be managed accordingly.