Peripheral Blood Smear (Blood Film), Types, Materials Used And Procedure Involved In It

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In this article, we will share some information about peripheral blood smears and the procedure to perform them. And if you are interested in more articles, then make sure to comment with us below.

Peripheral Blood Smear (Blood Film):

The blood film or the blood smear test or peripheral blood smear ( PBS) is a type of blood test that is performed to get detailed information about the shape and the number of blood cells under the microscope, which helps the physician in diagnosis of any changes.

This test mainly focuses on RBCs, Platelets, and WBCs features.

Types of blood films:

1. Thin blood film (1mm-2mm): A small drop of blood is placed on a glass slide. This type of smear is used in most cases.
2. Thick blood film (1cm): A large drop of blood placed on a glass slide. This type of blood smear enables more efficient detection of parasites in the collected blood specimen.

What causes abnormalities in the structure of cells?

• A blood film is found abnormal when there are variations in the morphology of cells like changes in the color, shape, size, and number of cells in the blood sample.

• The abnormalities in the white blood cells are caused due to inflammatory difficulties or due to other infections.

• The abnormalities in the red blood cells are caused due to the deficiency of vitamins and minerals. And also due to inherited disorders like sickle cell anemia.

• The abnormalities in the platelets are due to the number of counts of more or fewer platelets.

What conditions does the blood film test help to diagnose?

The peripheral Blood Smear test helps the physician to diagnose the following conditions:

• Jaundice.

• Bone pain.

• Anemia.

• Sickle cell anemia.

• Discoloration of the skin (Abnormal bruising).

• Severe infections.

• Persistent flu-like symptoms.

• Viral infections of cough/sneeze.

• Sudden weight loss, etc.

Materials required to perform blood film:

• Syringe & needle.

• Blood preserving EDTA vacutainer.

• Tourniquet.

• Sterile lancet.

• 70% isopropyl alcohol.

• Microscopic glass slides.

• Spreader slide.

• Stain.

• Stopwatch or timer.

• Patient's blood.

• Microscope.

• Water tap, etc.

Procedure to perform peripheral blood smear:

• Collect the blood sample in an EDTA vacutainer after drawing it from the patient's body by venipuncture method.

• One should use a capillary tube or micropipette to transfer a drop of blood from the vacutainer to a clean microscopic glass slide.

• Make it a notice, if blood is collected by other techniques like fingerprick or heel puncture, you should discard the first drop of blood and then transfer the other drops to a clean glass slide.

• You should place the drop of blood in the center of the clean glass slide, leaving about a 1cm gap between the drop and the one end of the glass slide.

• Keep the glass slide on a flat surface and hold it with your index finger and thumb, then place a smooth, clean edge spreader slide on the specimen slide at an angle of 30°-45°.

• Carefully spread the sample of blood with a spreader slide.

• Make sure that the smear should resemble the shape of the tongue.

• Then allow the blood smear to air-dry completely.

• After it is completely dry, use a glass marking pencil (lead pencil or glass marking pencil) to write the patient's name, identification number, and date of smear on the frosted end of the slide. (Do not use wax pencil or marker or any pen as it dissolves during the process of staining).

• The smear is then stained using Leishman's stain comprising of eosin, methylene blue with methyl alcohol.

• After staining, keep it for three minutes, then add a buffer solution to the slide and keep the smear for about 10-15 minutes.

• After 15 minutes wash the slide under the running tap water, such that water is falling on your hand and flows through the slide.

• Do not wash the slide directly under tap water, as it will wash out the smear.

• After washing, keep the smear for some time to dry and then examine the glass slide under the microscope to detect any abnormalities in the morphology of the cells.

This is the perfect procedure to perform the peripheral blood smear.

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