Pitfalls in Urinary Tract Cytology: Algorithmic Approach and The Paris System

Abstract

Urine cytology is sensitive for detection of high-grade urothelial carcinoma. However, urine is a hostile medium for the exfoliated cells leading to degenerative changes with various interpretation challenges. Chances of misinterpretation can be avoided if the interpreter is conversant with potential pitfalls during evaluation of urine cytology. The causes may be due to pre-analytic, analytic, or post-analytic factors which include method of collection (voided versus cystoscopic versus bladder washing versus other procedures), use of preservative if any, and availability of relevant clinical history. Most common pitfalls are related to low-grade urothelial neoplasms; however, clinically critical are those which are mimickers of high-grade urothelial carcinoma (HGUC).