Smearing techniques: How good do you smear?

Back to the days when I was a third year medtech student, I struggled a lot making the so-called ideal blood smear. It is still fresh in my memory how I wipe again every failed smears just to save slides and how frustrated I am when instructors tell me that my smears are not good enough. I asked a lot of times when will I ever be adept in smearing until over the years I developed a technique on my own on how to make a good one and realized I learned much from it.

So basically, what is a good-quality blood smear?

• it should have a feathered end
• has a rainbow sheen when reflecting the light 
• length is 3/4 of the slide
• has margin; optional 

Factors to consider:

• Angle- around 30-40 degrees; adjust the angle higher if the blood is thin as seen in anemic patients or lower if the blood is thicker mostly evident from dehydrated patients
• Speed- requires a very smooth motion
• Amount of blood- one drop of blood is enough to create a monolayer 
• Pressure-  push the spreader completely across the slide. Avoid jerky movements.
• Spreader- it is better to check if the surface is still smooth to facilitate the spreading smoothly. 

First technique: Horizontal spreader approach

One disadvantage employed in this technique is the lack of margin. Make sure to tilt the horizontal spreader gently until the blood is evenly distributed to the sides before smearing. 

second technique: vertical spreader

Draw the spreader backwards. When the spreader is already in contact with the blood provided the blood spreads evenly on the spreader) gently push the spreader to make a smear

Third technique: This is what I call the 'Youtube style' as this is the frequently demonstrated technique from youtube tutorials. I think you have to learn the vertical approach first as prerequisite to this because you don't carry the slide and spreader up. Guide the spreader lightly while the slide is held on a flat surface and you'll make an evenly distributed smear with a nice feathery edge. My preferred technique.

To conclude, it is really essential that you master how to make good smears for your benefit and to the pathologist as well. Examination of blood smear is an integral part in hematological testing. Your differential count depends on your smear. Constant practice makes perfect so don't get frustrated if you can't make it today. Better yet, develop your own technique where you comfortable doing. Don't forget to label the patient's name on the slide.