CLINICAL LAB SCIENEC

CHAPTER 13: HEMATOLOGY AND COAGULATION 335
Evaluation of Results
A blood smear that has been properly made and stained greatly
facilitates the accuracy and efficiency of the hematology department
(Figures 13-4).
HEMATOLOGY AND COAGULATION PROCEDURE #2
Practical White Blood Cell Differentiation
Principles
The first step in performing the white blood cell (WBC) differentiation
is to examine the slide under low power to look for consistent
distribution of both white and red cells. The experienced hematology
professional will develop a quick “look-see” evaluation of the
blood picture presented. The quality of the film is readily
obvious to the trained eye, and increased or decrease
WBCs, quality and numbers of platelets, and whether
RBCs are normal in color, size and shape are evident.
In some cases, a repeat slide may be necessary due to
quality of the slide and the staining characteristics.
WBCs are classified into different type. Normally,
100 to 200 cells are counted and a percentage is calculated
for each type to determine if the ranges of types
of WBCs fall within a normal pattern. In various disease
presentations, certain WBC types are either increased
or decreased, or may appear as immature stages. The
types may be counted using an automated or mechanical
counter (Figure 13-5). WBC characteristics are useful in
diagnosing and monitoring a variety of diseases such as
leukemias and anemias.
Remember that the technical laboratory
professional should not merely focus on WBCs during
a white blood cell differentiation procedure but should
evaluate all cellular components of the smear, including
platelet appearance and RBC appearance.
To determine the type of leukocyte (WBC) , the
student should consider the following characteristics,
in conjunction with the illustration of cell types in
Figure 13-6:
• Look at the size of the cell. Monocytes are almost
always larger than lymphocytes.
• Eosinophils have more granulation than basophils
and are coarser than neutrophils.
• Neutrophils are smaller than eosinophils in most
cases.
Critical Reminder
One may count 200 cells if desired,
although the standard is 100 for the
experienced worker. The higher number
will ensure a more accurate percentage
of the various WBCs. For this microscopic
manual count, a WBC differential counter
is used such as the one illustrated in
Figure 13-6.
FIGURE 13-4 Normally distributed red and white blood
cells on properly made blood smear. (A) Red blood
cells. (B) Large lymphocyte. (C) Neutrophil. (D) Eosinophile.
(E) Neutrophil. (F) Monocyte. (G) Platelets.
(H) Small lymphocyte. (I) Band cell. (J) Basophil.
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