Blood Smears made easy for vet nurses

When running a haematology analysis (including in-house) on a patient, it is recommended you also perform a blood smear. Blood smears are used to detect cell abnormalities and confirm the numbers provided by the analyser. The smear may also be sent to an external laboratory for a pathologist to assess, either by itself or in conjunction with an EDTA sample for them to run the haematology.

Using a beveled or ground edge slide as your spreader will give you a nicer film than using a cut edge slide.

1. Ensure that you use clean, dry microscope slides (only handle the slide by the sides).
2. Label a slide with the patient name and ID at one end of the slide.
   1. Place a small drop of blood around 3mm in size (fresh or mixed with EDTA) at the labelled end of the slide. This drop can be acquired by using a haematocrit tube or with a small-gauge needle and a 1ml syringe.
3. Holding the blood sample slide by the edges, keep it firmly on the bench. Use a clean spreader slide place the edge of this in the middle blood sample slide.
4. Draw the spreader back into the drop of blood at an angle of 45 degrees and allow the blood to spread along the edge of the spreader. If your patient is anaemic, then increase the angle to get a thicker smear.
5. Push the spreader away from the blood drop using a single, smooth motion.
6. Ensure that the end of the film has a ‘feathered edge’.
7. Let the film air-dry. Some clinics like to speed up the drying process with a hairdryer. If you do, ensure you only use a low temperature and hold 30cm away on the underside of the slide.
8. If you are unsure of the quality, make a few then select the best.
9. If examining the smear in-house, stain the slide after it dries. If the smear is being sent to the laboratory, allow it to dry and place it into a slide container (do not stain the slide).

SMEAR TOO SHORT

Try using a larger droplet of blood. You can also try decreasing the angle of your spreader slide and going a little slower.

SMEAR TOO THICK OR LONG

Try a smaller drop of blood for your next slide. You can also try increasing either the angle of your spreader, or move a little faster.

PAUSES OR HESITATION

It’s all about practice. You need to have a smooth action and keep the spreader slide edge in full contact for the entire movement.

TOO THIN

Firstly try using a larger drop of blood.

Failing that, increase the angle of your spreader side and/or decrease the speed at which you push it.

WAVES, RIDGES OR UNEVEN ENDS=

Ensure you are keeping your motion smooth and with the spreader slide in contact the whole time.

Try using a ground or bevel edge slide for the spreader slide,
not a cut edge. The cut edge slides can leave ridges and not run as smooth.

Try relaxing your wrist and use a little less pressure when pushing the spreader slide. A little faster could also help.