CLINICAL LAB SCIENEC

CHAPTER 13: HEMATOLOGY AND COAGULATION 331
Preparation and Staining of Blood Smear
for Differential
The blood smear or “film” is made from a drop of blood spread evenly on a slide
and stained. While blood cell film preparation is a simple and straightforward
procedure, the quality of blood films in many laboratories is often poor. It is
important to ensure that the film is well made and stained with a valid and effective
stain. A properly made and stained blood smear should be demonstrated
by the instructor. The student should duplicate the streaking and staining of the
film, and sufficient practice should be provided for the student to become familiar
with identifying the various WBCs.
In the Lab
BASIC HEMATOLOGY AND COAGULATION PROCEDURES
HEMATOLOGY AND COAGULATION PROCEDURE #1
Preparing a Stained Blood Smear (Film)
Principles
Preparing a blood smear that can be stained adequately and viewed
for accuracy is the most important step in producing a complete blood
count. The cells must be distributed properly to avoid distortion of
shapes by adjacent cells. Visual examination by microscope should
confirm the results of the complete count obtained from an autoanalyzer.
Such examination is often necessary when the autoanalyzer
finds an irreconcilable discrepancy in the results obtained.
Wright’s or a combination of Wright’s-Giemsa stain is most often
used for routine blood smear examinations; other special stains are
used for determining certain pathological conditions of the blood. It is
paramount that the blood be spread properly over the slide or it is impossible to accurately
and thoroughly examine the sample. Blood smears may be prepared directly
from a finger “stick” or from an anticoagulated (non-clottable) specimen within 1 hour
of collection. Specimens in an anticoagulated tube must be mixed adequately before
using them to prepare a blood smear.
Equipment and Supplies
1. Gloves, disposable paper towels, and disinfectant or other cleaning solution
2. Sample from a finger “stick” or from an anticoagulated (non-clottable) specimen
examined within 1 hour of collection
3. Microscope slides
Safety Alert
It is quite easy to break the slide used to
draw blood across the surface of another
slide if too much pressure is placed
on the slide, or if the slide is not held
correctly. Please observe the instructor’s
demonstration and avoid a nasty cut that
would require an incident report being
filed, and possible medical treatment
and follow-up to prevent complications
or to determine if the student has been
exposed to infected blood.
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