Differential Leukocyte Count in Blood Smears

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Questions and Answers

What is the aim of differential leukocyte count?

To examine the morphology of platelets

To determine the relative count of different types of leukocytes (correct)

To count the total number of white blood cells

To identify different types of red blood cells

What is the purpose of using EDTA anticoagulant blood in preparing peripheral blood smear?

To slow down the degenerative changes in blood cells (correct)

To enhance the visibility of platelets

To preserve red blood cell morphology

To accelerate the staining process

Why should differential smears be made as soon as possible?

To allow for easier examination of the smear

To prevent degenerative changes in blood cells (correct)

To minimize the risk of contamination

To allow for better staining of blood cells

What is the purpose of spreading the blood drop along the line of contact of the spreader with the slide?

To create a thin film of blood Signup and view all the answers

What is the desired length of the film in a peripheral blood smear?

3-4 cm Signup and view all the answers

What can a deviation in the percentage of different types of leukocytes indicate?

An allergic reaction or parasitic infection Signup and view all the answers

What is the ideal time frame for preparing a peripheral blood smear after collection?

Within 3 hours after collection Signup and view all the answers

Why is it important to examine the blood smear accurately?

To provide an accurate interpretation of the blood cell morphology Signup and view all the answers

What determines the thickness of the spread when pulling the smear in a blood film preparation?

The angle of the spreader slides Signup and view all the answers

What is the purpose of a thin smear in a blood film preparation?

To describe the blood Signup and view all the answers

What is the composition of Giemsa stain?

Giemsa powder (0.3g), glycerin (25ml), and methyl free alcohol (25ml) Signup and view all the answers

What is the purpose of fixing the blood film with methyl free alcohol?

To preserve the morphology of the cells Signup and view all the answers

What is the normal range for Neutrophils in a blood film?

35-85% Signup and view all the answers

What is the purpose of the differential leucocytes count?

To identify the different types of leucocytes Signup and view all the answers

How many cells should be counted in a differential leucocytes count?

100 cells Signup and view all the answers

What is the normal range for Lymphocytes in a blood film?

20-25% Signup and view all the answers

Study Notes

Differential Leukocytes Count

Aim and Principle

The aim is to prepare a blood smear and count different types of leukocytes to express their relative counts in percentage.
The principle is based on the fact that the number of different types of leukocytes may deviate from the normal range, indicating certain disease states or infection.

Preparation of Peripheral Blood Smear

Blood smears must be prepared correctly to provide an accurate interpretation.
EDTA anticoagulant blood is used to minimize degenerative changes in blood cells.
Differential smears should be made as soon as possible, no later than 3 hours after collection.

Procedure for Slide Preparation

A drop of blood is placed on a slide, and a spreader is used to make contact with the drop at a 45-degree angle.
The drop should spread out quickly along the line of contact, and the film should be spread by a rapid, smooth forward movement of the spreader.
The thickness of the spread is determined by the angle of the spreader and the size of the blood drop.

Staining

Different stains used to count leukocytes include Wright stain, Leishman stain, and Giemsa stain.
Giemsa stain composition: 0.3g Giemsa powder, 25ml glycerin, and 25ml methyl-free alcohol.
The stock solution is diluted by adding 1ml of stain to 9ml of buffered water before use.

Normal Ranges and Mean Values

Neutrophils: 35-85%, mean value 60%, size 10-14μ.
Lymphocytes: 20-25%, mean value 30%, size 6-12μ.
Monocytes: 2-6%, mean value 4%, size 12-18μ.
Eosinophils: 0-4%, mean value 2%, size 10-14μ.
Basophils: 0-1%, mean value 0.5%, size 10-14μ.

Staining Method

The blood film is fixed with methyl-free alcohol for 2 minutes.
Giemsa stain is poured over the smear for 8-10 minutes.
The smear is washed with buffer and dried.

Counting

The dry and stained film is examined without a cover slip under an oil immersion objective lens.
The area is chosen where cell morphology is clearly visible.
A total of 100 cells are counted, recording every white cell seen in a table with headings for each type of leukocyte.

Results Interpretation

The results of the lymphocyte count are interpreted based on the mean volume of each type of leukocyte.

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Description

Learn to prepare and analyze blood smears to count different types of leukocytes, understanding their percentage counts to diagnose diseases like allergic reactions, parasitic infections, and more.