LABORATORY DIAGNOSIS
PERIPHERAL BLOOD
SMEAR
PERIPHERAL BLOOD SMEAR
A properly prepared blood smear is
essential to accurate assessment of
cellular morphology
The wedge smear is the most convenient
and commonly used technique for making
PBS
PERIPHERAL BLOOD SMEAR
Wedge technique of making
PBS
A. Correct angle to hold
spreader slide
B. Blood spread across width
of slide
C. Completed wedge smear
PERIPHERAL BLOOD SMEAR
Characteristics:
– About two thirds to
three fourths of the
slide is covered by the
smear
– It is very rounded at
featheredge (thin
portion), not bullet
shape
– Lateral edges of the
smear should be
visible
Well-made PBS
PERIPHERAL BLOOD SMEAR
Characteristics:
– It is smooth without
irregularities, holes, or
streaks
– When the slide is held
up to light, the
featheredge of the
smear should have a
“rainbow” appearance
– The whole drop is
picked up and spread
Well-made PBS
PERIPHERAL BLOOD SMEAR
Examples of unacceptable smears
PERIPHERAL BLOOD SMEAR
Examples of unacceptable smears
PERIPHERAL BLOOD SMEAR
Staining of PBS
Purpose of staining is to identify cells and
recognize morphology easily through the
microscope
Uses Wright stain or Wright-Giemsa stain which
contain both eosin and methylene blue 
polychrome stains
PERIPHERAL BLOOD SMEAR
Optimally stained smears have the
following characteristics:
1. RBC’s should be pink to salmon in color
2. Nuclei are dark blue to purple
3. Cytoplasmic granules of neutrophils are
lilac
4. Cytoplasmic granules of basophils are
dark blue to black
5. Cytoplasmic granules of eosinophils are
red to orange
6. The area between the cells should be
clean and free of precipitated stain
PERIPHERAL BLOOD SMEAR
Peripheral smear
examination
Correct area of blood in
which to evaluate cellular
distribution and perform
WBC estimate
PERIPHERAL BLOOD SMEAR
Peripheral smear
examination
“Battlement” pattern for
performing a WBC
differential count