The Value of Conventional Urine Cytology in the Diagnosis of Residual Tumour after Transurethral Resection of Bladder Carcinomas

Background: Transurethral resection leads to characteristic histological changes of tissue repair (’TUR cystitis‘), which also cause non-specific cytological changes. The aim of this study was to investigate the diagnostic sensitivity and specificity of conventional exfoliative urinary cytology in diagnosing residual urothelial carcinoma after differential transurethral resection. Patients and Methods: 417 urinary cytology specimens of all 374 patients undergoing primary (n = 326) or secondary (n = 91) transurethral resection of urothelial carcinoma of the bladder at our institution between June 1996 and December 1997 were examined. The cytology specimens were stained according to Papanicolaou’s method. The sensitivity and specificity of the cytologic diagnosis and of the tumour grading were compared with histological findings. Results: The overall sensitivity of urine cytology in tumour detection was 77.6% for primary lesions and 74.5% in the detection of residual carcinoma after transurethral resection. The diagnostic specificity was 77% and 84.3% respectively. The degree of sensitivity was dependent on tumour grade and was lower for well differentiated tumours. After transurethral resection, the sensitivity for grade 1 residual tumours was 11%, whereas it was 54% for grade 1 tumours before primary transurethral resection. Conclusions: The inflammatory changes following transurethral resection of primary bladder carcinoma cause reactive cytologic changes that make the diagnosis of well differentiated residual carcinoma more difficult. However, urinary cytology after transurethral resection has the same diagnostic accuracy for medium and poorly differentiated tumours as before primary resection and thus remains a very useful diagnostic tool.