Preparation of body fluid smears for microscopic examination requires concentration techniques that preserve cell integrity and morphology. Cytocentrifugation (also known as "cytospin") provides the best method for both concentrating cells in body fluid samples and maintaining cellular morphology. The cytospin process works by wicking fluid into a filter while fluids samples are spun into a central column and deposited in a mono-layer onto a defined area of a slide. This allows the cells to be concentrated for appropriate identification.
Most technologists working in the clinical hematology setting are familiar with the morphology of blood cells found in peripheral blood smears. Many of the same blood cells found in the peripheral blood are also found on cytospin preparations of body fluids. While the morphologies are similar between the two sources, there may be changes to the "comfortable/familiar" peripheral blood morphology that are introduced by the cytospin technique. Cytocentrifugation of body fluid samples can cause some morphologic artifacts. The technique can stretch and distort cellular and nuclear morphology and allow nucleoli to appear more prominent than would normally be seen in peripheral smears. Incorrect cytocentrifuge speed and time settings can accentuate these artifacts. Adding a drop of 11% or 22% albumin to the volume of a serous fluid sample being cytocentrifuged aids in preserving the cellular morphology. (Albumin should not be added to synovial fluid samples as they inherently have sufficient protein to preserve cellular integrity).
Cytospin, however, does not change nuclear:cytoplasmic ratios nor does it alter relative chromatin textures or clumping patterns. Though this technique can make cells appear larger than on the peripheral blood smear, it does not change cytoplasmic textures and granulation. Focusing on these features can make cytospin morphology less intimidating.