The value of ethanol as a fixative in urinary cytology.

Although 50% ethanol is widely used as a fixative in urinary cytology, the value of this procedure has received little systematic analysis. The purpose of this study was to examine the preservative qualities of 50% ethanol when added to freshly collected urine for both immediate and delayed processing. The results indicate that: (1) degenerative changes occurring in vivo are common among urothelial cells and probably represent the single most important factor in cell preservation in voided urine; (2) with few exceptions, fresh, unfixed urine yields the greatest number of well-preserved cells; and (3) reconstitution in either saline or 25% ethanol-saline and 24-hour storage result in increased cellular degeneration. For Millipore filter preparations, the addition of 50% ethanol has no apparent advantage, even when processing must be delayed for several hours.