Comparison of two preparatory techniques for urine cytology

Two methods of preparation of urine for cytology were compared retrospectively. In method 1 cells in the urine were fixed after the preparation of the smear; in method 2 the cells were fixed before smear preparation. Urine cytology reports were correlated with subsequent histological analysis. The specificities of urine cytology using both methods were high (99%). The sensitivity using method 1 was 87%; using method 2 it was 65%. This difference was significant. The cell preparation technique therefore significantly changes the sensitivity of urine cytology. Cellular fixation after smear preparation is preferable to smear preparation after fixation.