AI Blood Smear Analysis slide preparation

Shannon Mitchell Updated by Shannon Mitchell

Collect blood sample

  1. Select the largest vein and appropriate needle for blood collection.
  2. Use the minimum amount of alcohol and let dry prior to venipuncture, as alcohol can cause sample haemolysis.
  3. Minimise suction on the syringe, and do not draw it back too quickly.

Blood sample storage

  1. After blood is collected from the patient, it should be transferred to the EDTA sample collection tube.
  2. Remove the needle from the syringe and remove the cover from the blood tube for transfer if not using a BD Vacutainer® system.
  3. Fill the tube to the manufacturer’s recommended fill line.

Label slides

  1. Label the slides with the patient’s ID and date using a pencil.

Important: Markers and pens should be avoided, as they will wash off in the staining process.

Prepare the slide

  1. Mix the EDTA anticoagulated blood.
  2. Use a microhaematocrit capillary tube or precision pipette to draw blood from the just-mixed tube and gently place a drop onto the labelled slide. Care should be taken not to tap the tube against the slide.

Important: A wooden stick should not be used for the blood transfer, as platelets and white blood cells tend to adhere to it.

Place spreader slide

  1. Place the spreader slide on top of the labelled slide in front of the blood droplet and hold at a 30° to 45° angle.

Spread the blood

  1. Draw the spreader slide back until it makes contact with the blood droplet.
  2. Capillary action will draw the sample toward the edges of the slide.

Important: Do not allow the blood to reach the edges of the slide.

Complete the spread

  1. Before the blood reaches the edges of the slide, push the spreader slide away from the sample blood drop across the bottom slide with a smooth, stable and fluid motion. Maintain the same angle throughout the motion, and do not apply downward pressure. This should produce a uniform blood film covering approximately ½ to ⅔  of the slide. 
  2. Let the slide air-dry to avoid air-drying artifacts.
    Important: Do not heat-fix the slide.
  3. After the blood smear is made, visually inspect the slide. The smear should look like a thumbprint and exhibit a visible feathered edge at its end.

Stain the slide

  1. Using a Romanowsky-type stain (e.g. Diff-Quik™), closely adhere to the manufacturer’s instructions for processing:
    1. Fixative
    2. Red stain
    3. Blue stain
    4. Water rinse
    5. Air-dry.

Regularly replace the stain according to the manufacturer’s recommendation or when the stain has been compromised.

Place the coverslip 

  1. After the slide has been stained and air-dried, place a drop of immersion oil on the smear.
  2. Then place a 24 x 60 mm coverslip on the slide.
  3. The immersion oil will allow the coverslip to adhere to the slide.
  4. The slide is now ready to be scanned by Vetscan Imagyst.

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