Microhematuria found by mass screening of apparently healthy males.

Preparation of urinary sediments was adapted for mass screening purposes. The procedure, characterized by most careful collection and transfer of the sediment and by a rigidly controlled work scheme, was tested in a limited population screening program with 446 healthy male participants. A capacity of 100 samples per 12 manhours was achieved. The procedure was found effective in collecting the cellular content, but there was serious cytolysis due to a 11 hours delay between micturition and processing. An unexpected finding was the presence of erythrocytes in all the samples. In 8.8 per cent of the smears more than ten RBC/hpf were present. The significance of this feature is still in study, but it might prove to be a useful prescreening criterion in the cytologic assessment of bladder cancer in large populations.