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