Collection fluid helps preservation in voided urine cytology

Degenerative change caused by delay in processing contributes to false-negative and false-positive diagnosis of urothelial carcinoma in cytology. The aim of the study was to see if the use of a collection fluid for urine samples made a significant difference to urine cytology diagnosis, and if one was better suited for routine use in the hospital laboratory. Three cell collection fluids were evaluated by analysing the preservation and degeneration of cells in urine samples, as was the routine preparation which did not use a collection fluid.

In the design study 50 voided urine specimens were taken at random from the hospital haematuria clinic. Three commercially available collection fluids cytolyt, cytospin and cytoRich Blue and the hospital's routine conventional preparation of urine were compared. The degree of degeneration, and so preservation, was assessed by a table of chosen criteria; then ranked and analysed by Friedman's nonparametric test, at P = 0.05. A second table showing the cell content of each slide was also made.

These showed no significant diagnostic difference between the collection fluids, but there was a significant difference between the collection fluids and the routine preparation. Minor differences that do not affect diagnosis, such as crystals and ghost red blood cells, were noted in cytospin and cytoRich Blue.

It is recommended that a collection fluid is used. This choice should be made after health and safety issues and cost are considered.