Different methods for preparing the cytology smears are available. Nevertheless, these methods work best with different types of specimens. Understanding each procedure can help to determine the right approach for particular cases, eliminating procedures that may yield suboptimal findings and hinder diagnosis. Easy manual techniques with a minimum of supplies and equipment will offer excellent preparations. Different types of cytological smear are:
- Direct smear
- Large volume centrifugation
- Small volume centrifugation
- Membrane filtration
- Density gradient centrifugation
- Gravity sedimentation
- Cell blocks preparation
DIRECT SMEARS
The direct spreading makes a cytological smear of the specimen onto a glass slide. Forward smears are the easiest and quickest of the various methods to move cells from a fresh specimen to a sheet. Specific smears are scrapings, brushings, Tzank smears, smears for viral inclusion. Clinical personnel often make smears at collection time. This includes a system that is quick to interact, which is simple to execute, and that prevents the drying of the soil.
Blood smear technique
- Place a small drop of deposit near one end of glass slide.
- Touch a second slide to a front edge of the drop
- Push the second slide across the surface of first slide.
- The final preparation is thin and uniform.
- The technique is useful for producing thin air dried smear for Giemsa type stain.
Nickel method
It is simple to describe and fast to execute. Spreading of the specimen in a close circular fashion instead of laterally reduces the risk of dried dust. To extract and stain cytology slides, stop cotton swabs as the fibers remove moisture from the specimen, inducing drying of air and cellular distortion.
Procedure
- Smear the substance from the scraper or brush onto a numbered slide in a nickel-sized region utilizing a circular motion.
- Immediately fix by immersing in 95 percent ethyl alcohol or by flooding the slide with fixative cytology spray.
Pull-apart method (Squash method)
The pull-apart approach is a successful general-purpose strategy for mouse-free cellular fluids. It is easy and allows cells still monolayer
Procedure
- Place 2-3 drops of sediment on a labeled glass slide.
- Place another labeled glass slide upside-down on top.
- Allow the sediment to spread naturally.
- Gently pull the slides apart endways
- Fix immediately to prevent air-drying, using 95% ethyl alcohol or a cytology spray fixative.
Crosshatch method
A crosshatch approach is an excellent option for cellular body fluids, especially those that contain lots of blood. Spreading the sample back and forth deposits the more massive, more sensitive cells at the ends of the ‘heads’ and removes them effectively from the blood cells.
Procedure
- Using a disposable loop, place 2 or 3 loopful of sediment on a labeled glass slide
- Working quickly, spread the specimen diagonally, going back and forth and corner to corner.
- Fix immediately to prevent air-drying by quickly submerging in 95% ethyl alcohol or flooding with a cytology spray fixative.
- Ensure that a sufficient quantity of spray fixative is used.
- If the sediment beads form, spread it again with the wire loop, attempting to get a monolayer of cells.
Crush (mash) method
Specimens containing dense mucus may need more vigorous intervention to split up the mucus properly. This manual procedure is beneficial to disperse the cells effectively and to create an even smear
Procedure
- Pick out any streaked or blood-tinged material and place it on a labeled glass slide.
- Place another labeled glass slide on top, and mash the material forcibly, but carefully, between the two slides, to yield a smear that is thin and evenly distributed over the entire slide.
- A quick “slap” back and forth motion of the slides is helpful to break apart chunks of material that may be in the specimen and thus allow a thin, even preparation.
- Fix immediately to prevent air drying, using 95% ethyl alcohol or cytology spray fixative.
LARGE VOLUME CENTRIFUGATION
Historically, large-volume centrifugation has been used to keep the fluid specimen contained. The goal is to choose a buffy coat for smear preparation after fluid centrifugation. The buffy coat coating is a portion of centrifuged fluid that includes white blood cells and tumor cells, if present.
Fishtail smear
If the specimen is suspected to be hemorrhagic fishtail smear is suggestive. Buffy coat is collected for the selection of malignant cells. A drop of buffy coat in the shape of the fishtail is scattered over a glass slide.
SMALL VOLUME CENTRIFUGATION
Small volume (average 0.5ml) specimen that does not produce a sufficiently buffy layer for a smear may be handled by cyto-centrifugation. A cytocentrifuge is a system that uses centrifugal force to spin the cell directly onto a glass slide in a fluid suspension. This prevents having to create a sample stain.
MEMBRANE FILTRATION
Specially designed filter paper comprising microscopic pore with membrane filtration from which fluid sample can be drawn. Big cell-like tumor cells will accumulate in a thin, even layer on the pipe. Afterward, the sheet is moved to a microscopic panel.
DENSITY GRADIENT CENTRIFUGATION
Through this procedure, a determined sample aliquot is cautiously dispensed in a centrifugal tube at the tip of a pressure gradient gas. Concentrated sugar water is applied to the specimen with a density gradient solvent and centrifuged, splitting various forms of cells into layers according to particular gravity.
GRAVITY SEDIMENTATION
A glass slide is clamped into a settling container, and a cell suspension is attached. It has allowed enough time for the cell to settle under gravity on the slide. The slide may be either electrically or covered with the correct substance to promote cell adhesion. The commonly utilized adhesive is albumin and poly-l-lysine.
CELL BLOCKS PREPARATION
A cell block is a way to process as a histopathological specimen a cytology sample. For a more precise cytopathological examination, cell blocks formed from leftover tissue fluids and fine-needle expectations may be useful.