Chapter 52- Preparation of Cytology Smears
Modified Compression Preparation
•Rotate second slide 45 degrees and lift upward
Wedge Smear
●A drop of fluid is placed on the slide. approximately 1 to 1.5 cm from the end. ●Second slide is pulled backward at a 30- to 40-degree angle until it makes contact with the drop. ●The fluid spreads across the width of the spreader slide. ●The spreader slide is then quickly and smoothly pushed forward until all fluid is drained away. ●Creates a feathered edge.
Starfish Smear
●Drags the aspirate peripherally in several directions with the point of a needle ●Tends not to damage cells, but leaves a thick layer ●Ideal for viscous samples
Papanicolaou Stains
●Excellent nuclear detail and delicate cytoplasmic detail ●Do not stain cytoplasm well ●Do not demonstrate bacteria ●Requires many steps and time; difficult to locate, prepare, and maintain in a practice
Compression Preparation
●Expel contents of aspirate onto the middle of slide ●Gently place a second slide at right angles to the first slide ●The spreader slide is quickly and smoothly slid across the prep slide. ●Downward pressure should not be placed on the spreader slide.
Cytology Techniques
●Impression smears ●Compression or modified compression preparations ●Line smears ●Starfish smears ●Wedge smears ●Type of preparation depends on characteristics of the sample
Line Smear
●Low cellularity or small volume sample ●A drop of fluid is placed on the slide and a blood smear technique is used except. ●The spreader slide is raised directly upward approximately three fourths of the way through the smear, creating a line containing a higher concentration of cells.
Combination Techniques
●Place aspirate on the middle of slide ●Place prep slide on flat surface ●Pull spreader slide backward at 45-degree angle until it makes contact with approximately one third of the aspirate ●Then smoothly and rapidly move spreader slide forward ●Next place spreader slide horizontally over back third of aspirate at a right angle ●Quickly slide the spreader slide across the prep slide ●This preparation leaves three different types of areas to evaluate
Staining Problems
●Poor stain quality can be perplexing ●Can be avoided if: -Always use clean (new) slides -Fresh, well-filtered stains and fresh buffer solution should be used. -Cytologic preparations should be fixed. -The surface of the slide should not be touched by human hands. -Avoid contamination with foreign substances
Preparations of Smears from Fluid Samples
●Should be prepared immediately after collection ●If possible, should be collected with EDTA ●Cellularity, viscosity, and homogeneity of the fluid influence the selection of smear techniques.
Fixing and Staining the Cytology Sample
●Step ensures the highest quality preparation. ●Fixed before staining ●Preferred fixative is 95% methanol. -Must be fresh and not contaminated -Protect from evaporation and dilution ●Prepared slides should remain in fixative for 2 to 5 minutes.
New Methylene Blue
●Useful adjunct to Romanowsky stain ●Stains cytoplasms weakly, but gives excellent nuclear detail ●RBCs do not stain with NMB.
Submission of Cytologic Preparations, Samples for Interpretation
●When in-house evaluations do not furnish sufficient reliable information, the samples should be submitted to a veterinary clinical pathologist or cytologist. ●Submit 2 to 3 air dried unstained smears and 2 to 3 Romanowsky-stained smears. ●Fluids—direct smears and concentrated smears and EDTA and red-top tube should be submitted. ●Protect slides when mailing. ●Do not mail unfixed slides with formalin-containing samples
Romanowsky stain
●Wright, Giemsa, Diff-Quik, DipStat ●Inexpensive, readily available, and easy to prepare, maintain, and use ●Stain organisms and the cytoplasm of cells ● Slide must be air dried. -Preserves and fixes the cells to the slide ●Acceptable for staining cytologic preparations ●Each type of stain has a unique staining procedure.
