Lecture 3 Flashcards
WBC Count
Total Number of WBC reported in x10^9/L
WBC
Differential
Differentiates’ the five types of White blood
cells
RBC Count
Total Number of RBC reported in x10^12/L
PLT Count
Number of platelets reported in x10^9/L
Specific RI given according to
what is RI
Represents the results seen in the majority of healthy people in SI units
Specific RI given according to (where there is a difference):
‒ Gender
‒ Ag
Systematic Approach to CBC Interpretation
All counts within Reference Intervals
● No ‘flags’ by analyzer
● No follow up necessary – CBC reported
if there are flags it an be “L” for low counts “a” for action
it can have messages like anemia so you may have to do a smear and assess
Purpose of the PBF
Confirm CBC results
-Pathological - Confirm abnormal counts and/or indices
-Sample - Identify sample integrity issues (e.g., microclots)
Aid in the diagnosis of various disorders
- Demonstrate abnormalities not present in the CBC
-you see abnormal morphology or identify early or immature cells
Macroscopic Examination
Slide label - identification , legibility
Smear quality - direction of smear, length, spreading overall stain quality “feathered edge”
Microscopic Examination
done on low power 10x
Smear quality - even distribution of cells, artifacts like debris improper drying
Stain quality - if they have been stained properly, stain deposits
Specimen quality - microclots (fibrin strand) or platelet clumps -look at feathered edge or the edge of smear
when on 10x what will you Specifically look for in PBS Examination
-find an acceptable scanning area - monolayer or body of smear
- find a spot with even distribution and arrangement of cells - if too many WBC pushed to the edges - make a new smear
-scan the tail and edges for parasites - looks like a snake
how to find the monolayer on 10x
start at the tail - feathered edge and work your way inwards
the body is the monolayer it is found in between the middle and last third [ | ; | ]
the head of the smear is the thick area a little after the drop of blood before you reach the middle
where to find the monolayer and why is it the best place to look at
find a spot where the RBC are just touching look for salmon colored RBC some full and some with a pallor (clear middle)
this is where you do the estimates , diffs, morph assessments for RBC, WBC and PLTs
what is looked at on 40X objective
1.WBC & Platelet Estimates
2. 100-cell WBC Differential
3. RBC Morphology
4. WBC Morphology
5. Platelet Morphology
why are WBC and PLT estimates useful
estimates helps to conform automated counts and identify errors in processing
- if there are differences in the estimated and automated counts then maybe it was made from the wrong patients blood or a smear was mislabeled
procedures for estimation vary between different sites
how to do a WBC estimate
scan the smear on 10x - find the monolayer
then go on 40x and count the WBC in 10 random fields.
use this to determine the average # of WBC per High Field Power (HFP)
Check the estimates chart and report
Report as Decreased, Slightly Decreased,
Normal, Slightly Increased or Increased
how to do a PLT estimate
scan the smear on 10x and check for distribution - clumps, abnormal?
set to 40X
count the number of PLTs in a 10 random fields
Determine the average number per high
power field (HPF) and multiply by 2.5 x
109/L
Check the estimates chart and report
Report as Decreased, Slightly Decreased,
Normal, Slightly Increased or Increased
normal PLT
Normal platelet count
Average Number of platelets/HPF -60 - 180
Correlates with Estimated Platelet Count (x10^9/L) 150-450
Normal WBC count
Average Number of WBC/HPF -3-7
Correlates with Estimated WBC Count (x10^9/L) 3.6 - 10.6
what can causes sources of error when doing WBC and PLT estimates
doing counts in an incorrect area of smear
poor cell distribution
NRBCs counted as WBC
smudge cells counted as WBC
if PLTs are stained pale
if fibrin is trapping WBC or PLTs
if PLTs are clumped (poor phlebotomy technique or EDTA induced clumping)
Leukocytosis
increase in total WBC 10.6 x10^9
Leukopenia
Decreases in Total WBC count < 3.6 x 10^9/L
Thrombocytosis
Increases in PLT count > 450 x 10^9/L
Thrombocytopenia
Decreases in PLT count PLT < 150 x 10^9/L
what is the purpose of the wbc differential
CBC gives you the total WBC count of per liter of whole blood
what is a differential
determines the proportion of each type of WBC per liter of blood
a total count of WBC is not always significant because a normal count can have an abnormal diff%
what happens when you do an automated WBC diff
-the instrument “slots” cells into 5 mature WBC types
- will “flag” if there is a cell that does not meet criteria
-will ‘guess’ at abnormal types based on the same criteria
counts 1000s of cells
what happens when you do a manual WBC diff
- a visual interpretation of cells is done using morph criteria
- can identify the mature WBC and most immature ones
- can only do 100
what is the method for a WBC differential
count 100 WBC in the monolayer under 40x
count cells not artifact
identify as they are counted
the result is a % of each type identified
Battlement Pattern
when counting the WBC for a differential count 100 wbc in a pattern that is like a snake starting close to the edge of the monolayer||-||-
make sure you only move over one field - Inconsistent battlement method you may count the same cells twice
Challenges & Sources of Error\high WBC count
keeping track of a high count can be overwhelming
Challenges & Sources of Error
low WBC count
may end up deep in the thicker part of the smear where the WBC appear distorted and can be misidentified
mischaracterizing cells is also an error source
Cytoplasm
The protoplasm of a cell outside the nucleus
Nucleus
Central structure within a cell that contains the chromosomes
Chromatin
Deeply staining genetic material (DNA, RNA and proteins) present in the nucleus of a cell
Granules
Lysosomes – contain various proteins (e.g., enzymes)- staining is pH dependent
Vacuoles
Clear space formed in the cytoplasm of a cell
what to look for when comparing morphological characteristics
nucleus to cytoplasm ratio
shape of the nucleus and how it segmented
what does the chromatin look like? is it loose, clumped, condensed, is there nucleoli?
the color of the cytoplasm
the color of the granules
are there vacuoles present
the size of the cell
what will a neutrophil look like?
2-5 lobes in the nucleus
clumped chromatin
cytoplasm pink with lilac granules - it stains with neutral dye
look like sausage links
what will a banded neutrophil look like?
the nucleus isnt clearly segmented
the cytoplasm is pink
the chromatin is less clumped
what will a eosinophil look like?
the nucleas is 2-3 lobes
the chromatin is coarsely clumped
the cytoplasm is cream to pink
has large round orange/red granules - it stains with acidic dye
look like bubble letters
what will a basophil look like?
the nucleas is obsured - cant quite see it
clumped chromatin
the cytoplasm is lavender to colorless
there are purple black granules - the whole cell is basically purple- stains with basic dy
what will a lymphocyte look like?
the cytoplasm is sky blue
round oval nucleus
condensed to deeply condensed chromatin
a circle with a smaller circle inside that takes up most of the space
what will a monocyte look like?
the nucleus is shaped like a horseshoe
lacy chromatin - with little holes
the cytoplasm is blue -grey and looks like ground glass
its a larger cell
what types of Artifacts in PBF occur
smudge or basket cells- which are fragile cells that got damaged during smear prep
dontcount the cell if you dont clearly see the cell and the nuclear membrane
Pyknotic’ or ‘necrotic’ cells
where cells are dying and the nucleus is shrinking
the nucleus looks like little pebbles - dont count this cell
Distorted Cells- what type of error is that
its a lymphocyte that was squished
how do you report WBC
Relative Differential
● The ratio (% or fraction of 1) for each WBC type
● E.g., Neutrophils of 0.50 or 50%
what is the absolute differential
The relative percentage diff is converted to the total number of that specific leukocyte by multiplying the ratio to the total WBC count
● For example:
‒ Relative Neutrophil 0.50 ratio
‒ WBC count of 20.0 x 10^9/L
NEUTROPHILIA
An increase in # of neutrophils a 70% decrease
NEUTROPENIA
A decrease in # of neutrophils over 50%
LEFT SHIFT
specific increase in Band forms and some of the less mature forms of Neutrophils
LYMPHOCYTOSIS
An increase in the # of lymphocytes
LYMPHOPENIA
A decrease in the # of lymphocytes
MONOCYTOSIS
An increase in the # of monocytes
EOSINOPHILIA
An increase in the # of eosinophils
BASOPHILIA
An increase in the # of basophils above > 0.02 or 2% Relative
