Flow cytometric study comparing paired bladder washing and voided urine for bladder cancer detection

Paired bladder washings and voided urines from bladder cancer patients were compared as sources of exfoliated cells for detection of bladder carcinoma by flow cytometry (FCM). Bladder specimens fixed in 25% ethanol within sixty minutes of collection were found to be superior to unfixed bladder specimens. The percentage of specimens with good DNA resolution was greater for bladder washings (67% unfixed, 90% fixed) than voided urines (41% unfixed, 66% fixed). There was no difference in DNA resolution between specimens that remained unfixed less than one day, one day, or two days suggesting that the cells undergo the majority of degradation within a critical period soon after collection. Once fixed, there was no difference in DNA resolution for up to nineteen days, which suggests the feasibility of specimen transport to central FCM laboratories. Eighteen percent of unfixed bladder washings and 33 percent of unfixed voided urine specimens contained an insufficient number of cells (less than 5,000) at the time of analysis compared with 6 percent bladder washings and 17 percent voided urines fixed in 25% ethanol. Flow cytometry and cytology results were concordant in 28/43 (65%) of fixed bladder washings and 9/13 (69%) of fixed voided urine. Voided urine was unreliable in providing consistent FCM data due to the high number of specimens with poor resolution or insufficient cells and is not recommended as a substitute for bladder washing when screening high-risk populations or monitoring patients with past history of bladder cancer.