The qualitative results of FCM DNA analysis on fresh and fixed urine specimens (28 and 97, respectively) from 68 normal subjects and 10 patients with a past history of bladder cancer were compared. FCM DNA evaluability was not significantly different in fresh and fixed samples (63% vs 73%, respectively) whereas mean CV was significantly higher (7.3% vs 5.7%, respectively; p=0.04). A double FCM analysis on fresh and fixed urine was also performed in 16 cases. In this subgroup, the percentage of evaluable histograms from fixed urine specimens was slightly higher than that from fresh specimens. Aneuploid cases were found only in the fixed urine samples but the CVs from fresh and fixed cell suspensions did not differ. The absence of inflammatory cells with cytological analysis of the same samples was associated with low percentages of FCM evaluability and higher CVs. The use of fixed samples improves the quality of FCM DNA analysis permitting its use for screening programs.

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