Abstract
BACKGROUND: Urinary cytology plays a pivotal role in the non-invasive diagnosis of upper tract urothelial carcinoma (UTUC), especially where histological sampling is limited or technically challenging. The second edition of the Paris System for Reporting Urinary Cytology standardizes for evaluating cytological specimens. However, in clinical practice, urinary samples obtained from the UT often contain residual contrast media (CM) due to prior imaging studies; hence, the effect of CM on urinary cytology accuracy remains unclear. AIMS: The aim of this study was to examine the impact of CM on diagnostic performance of Paris system. SETTINGS AND DESIGN: This was a controlled in vitro laboratory study using RT112 human bladder cancer cells to model UTUC. MATERIALS AND METHODS: Cells were exposed to 100%, 50%, and 30% CM. Morphology, membrane integrity, and viability were assessed through time-lapse microphotography, Trypan blue, and MTT assay. Cytology was evaluated by a cytotechnologist. RESULTS: CM exposure caused concentration- and time-dependent cellular degeneration. After 60 min, viability dropped to 2.0 ± 0.1% (100%), 29.0 ± 4.7% (50%), and 75.1 ± 2.0% (30%), while membrane integrity declined similarly. Trypan blue staining showed integrity of 1.6 ± 0.1%, 15.1 ± 1.6%, and 46.5 ± 2.8%, respectively. Cells treated with 100% or 50% CM were classified as atypical urothelial cells (AUC) after 1 h, while 30% CM preserved high-grade urothelial carcinoma (HGUC) features up to 6 h. However, 24-hour exposure to 30% CM led to nuclear degeneration and cytoplasmic loss, again resulting in AUC classification. CONCLUSION: CM at higher concentrations and longer durations significantly compromise cellular morphology and diagnostic accuracy in urinary cytology.