Objective: To obtain an ideal cell block wherein the maximal number of cells are displayed within the smallest area on the block surface.
Study design: Cyto-Rich Red (AutoCyte, Inc., Elon College, North Carolina, U.S.A.) is added to fresh cellular sediment in a centrifuge tube at a ratio of 1:1. After two minutes, three to four drops of plasma and topical thrombin (5,000 U/10 mL) is added. The tube is then gently agitated for two minutes, until a gelatinous clot is obtained. The clot is then slid onto a lens tissue on top of paper towels. The lens tissue is folded once over the clot. By gently squeezing the excess fluid from it through the lens tissue into the paper towels, the clot is transformed into a flat, compact, densely cellular aggregate, which is painted with mercurochrome prior to fixation in formaldehyde.
Results: From each of the 495 cases, including 250 body cavity fluids, 170 fine needle aspirates and 75 endometrial brush biopsies, processed with the above protocol, there was a compact cell block containing packed cells or tissue fragments in a clean background devoid of red blood cells.
Conclusion: The compact cell block is about 10-20% the size of a conventional cell block, yet more cells are on display, thus reducing the need for deeper cuts and screening time while increasing the efficiency of cytodiagnosis. The compact cell block technique is particularly helpful for endometrial brush biopsies.