Steps for the Blood Cell Smear Test

Release time:

2014-03-19

Overview:

Microscopic examination of blood smears is a fundamental method in hematology, widely used in clinical practice. Preparing blood smears with appropriate thickness, uniform cell distribution, and excellent staining is one of the essential basic techniques in hematological examinations.
The smear method is one of the fundamental techniques for preparing biological microscopic specimens.

Steps:
It can be carried out in 5 steps.
Disinfection → Blood Collection → Smear Preparation → Staining → Observation

Disinfection
First, massage the blood-drawing site to promote smooth blood flow; then, disinfect the blood-drawing needle and the blood-drawing site (such as the fingertip) with alcohol.

Take blood
After the alcohol has dried, prick the skin to allow blood to flow out naturally—do not squeeze it. Take a clean slide and place a drop of blood about 4–5 millimeters from one end of the slide. Be careful to hold the slide by its edges only, avoiding contact with its surface. The slide must not come into contact with the skin at the site where the blood was drawn.

Push piece
Take a slide with smooth edges and use it as a spreader slide. Place one end of the spreader slide in front of the blood drop, then gently move it backward until it comes into contact with the blood drop, ensuring that the blood is evenly distributed at the point of contact between the spreader slide and the slide. Next, hold the spreader slide at an angle of 30° to 40° relative to the slide and smoothly push it toward the other end, as shown in the figure on the right. Once the smear is applied, quickly shake it gently in the air to allow it to dry naturally.

Dyeing
Using a special glass pencil, draw two lines on either side of the blood smear to prevent the staining solution from spreading beyond the edges. Next, drop the Wright’s stain (eosin-methylene blue) onto the blood smear until the entire smear is completely covered by the stain, and allow it to stain for half a minute. Then, add an equal volume of distilled water (or buffer solution) to the stain and continue staining for another 5 minutes. Finally, rinse off the staining solution with distilled water, blot dry with absorbent paper, and allow the slide to air-dry naturally before observation.

Observation
Red blood cells
Pale red, round cells without nuclei. Since erythrocytes are biconcave, the peripheral regions stain darker while the central regions stain lighter; their diameter is 7–8 micrometers.
Granular leukocytes
Neutrophilic granulocytes: Slightly larger in size than red blood cells, with a nucleus stained purple and lobed, typically ranging from 1 to 5 lobes. Diameter: 10–12 micrometers.
Eosinophilic granulocytes: Slightly larger than neutrophils, with a nucleus stained purple, typically consisting of two lobes. The cytoplasm is filled with large, eosinophilic granules that appear bright red. Their diameter ranges from 10 to 15 micrometers.
Basophilic granulocytes: Slightly smaller in size than eosinophilic granulocytes, these cells have cytoplasm containing purple-stained granules of varying sizes. The number of granules is fewer than that in eosinophilic granulocytes. The nucleus consists of 1–2 lobes and stains light blue. Their diameter ranges from 10 to 11 micrometers.

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