How accurate is urine cytology?

Exfoliative urinary cytology was performed on 260 new cases of histologically proven urothelial cancer. The site, size, shape and histological grade of the tumours were documented, and they were classified by the TNM system. Overall, urine cytology was positive in 135 (52%), suspicious in 28 (11%) and negative in 97 (38%) cases. Malignant cells were found most often when the urothelial tumours were large, papillary and solid, moderately or poorly differentiated and invasive (T2-4). Most upper tract tumours and those situated in bladder diverticula had positive urinary cytology. This study confirms that exfoliative urinary cytology is useful in detecting the more malignant bladder tumours including in-situ carcinoma, and other tumours in less accessible parts of the urinary tract.