[Effect of disturbing factors on the specificity of exfoliative urinary cytology].

In the clarification of hematuria and subsequent treatment, a high specificity is expected from urinary cytology when no tumor is present, because false positive results lead to unnecessary diagnostic measures. The aim of this study was to investigate different disturbing factors to determine the specificity of urinary cytology and whether the specificity can be increased by cytometry. Out of 150 patients with no malignant disease, 125 were affected by the following disturbing factors: urinary infection, urolithiasis, transurethral electroresection, utilisation of hypo-osmolar flushing solution or administration of contrast agents. In 5 patients who were diagnosed with urinary infection or urolithiasis, the urine was falsely cytologically determined to be tumor positive, an error which was corrected by cytometric analysis. Therefore, cytometric analysis should be carried out in patients in whom a tumor has been cytologically diagnosed in order to increase the specificity of urinary cytology.