Cellular fixation. A study of CytoRich Red and Cytospin Collection Fluid

To test a new fixative system (Roche Image Analysis System, Inc. [RIAS]) that may create a background free of blood and blood products, and to determine if the CytoRich Red system has a potential for automation of nongynecologic cytology. We compared the amount of red blood cells, background material and diagnostic ability in 40 bloody specimens prepared using the CytoRich Red system and our routine fixative, Cytospin Collection Fluid (Shandon, Inc.).

Thirty bloody, nongynecologic specimens and 10 fresh FNA surgical specimens were prepared by adding specimen to equal volumes (10 mL) of CytoRich Red Fixative and Cytospin Collection Fluid. After initial centrifugation, the specimens were resuspended and cytocentrifuged using the Cytospin III (Shandon, Inc.) and the Hettich Universal cytocentrifuge. To test system dependency, specimens from each fixative were prepared using the alternate method of cytocentrifugation. Slides from both fixatives were stained, coverslipped and reviewed for the presence of red blood cells, background and diagnostic ability.

Of the 40 CytoRich Red specimens, 92.5% (37) had little or no red blood cells as compared to 22.5% (9) of the 40 Cytospin Collection Fluid specimens. Seventy five percent (30) of the 40 CytoRich Red specimens showed reduction of background material in contrast to 15% (6) of the 40 Cytospin Collection Fluid specimens. Diagnostic ability using CytoRich Red was enhanced by the reduction of red blood cells and background material. CytoRich Red performed equally as well with each cytocentrifugation device.

CytoRich Red reduces red blood cells and background. Nuclear and cytoplasmic stain appear improved. This allows better evaluation of the cytologic features and interpretation of bloody specimens. It is non-system dependent and can be used with any method of preparation. Also, the reduction of background and blood lends itself to adaptation in the automation of nongynecologic cytology.