Lecture 2 - Blood film evaluation

Question 1

What should you do to validate the data given by a hematology analyzer?

Answer 1

look at blood film, also gives info that analyzer can’t pick up

Question 2

what are 4 things that a machine can’t pick up that a trained person can when evaluating blood films

Answer 2

1. RBC morphology: clues to anemia cause
2. WBC morphology: +/- inflammatory or neoplastic dz
3. platelet morphology
4. infectious dz/parasite

Question 3

what tube is preferred for making blood films

Answer 3

EDTA (purple top)

note: green top can be used but causes cells to appear blue/green

Question 4

ideally a blood films should be prepared…

Answer 4

make ASAP after collection (push film or cover slip method)
gently invert the tube 8-10 times
do not heat fix but rapidly dry to prevent artifacts

Question 5

staining blood film with diff-quik stain should let it sit in fixative for __

Answer 5

2 minutes

Question 6

3 romanowsky type stains and what is the most common one

Answer 6

1. diff-quik (most common)
2. wright stain
3. wright-giemsa stain

Question 7

__ is used to stain reticulocytes (anemia) and heinz bodies (oxidative damage)

Answer 7

new methylene blue

Question 8

__ is used to stain iron for BM samples

Answer 8

prussian blue stain

Question 9

using __ will prevent pH changes/funky looking slides

Answer 9

distilled water, but tap water is okay to use if it’s the right pH

Question 10

__ is a refractile artifact that can result in moth-eaten appearance and is normally due to poorly maintained quik stains

Answer 10

water artifact (water in fixative)

Question 11

__ is often mistaken for RBC inclusions (parasites like Mycoplasma)

Answer 11

water refractile artifact

Question 12

__ means that when focused up and down on cell the artifact “flashes” in one plane of focus, appearing dark in one while bright in another

Answer 12

refractile

Question 13

After prep and staining the film what should be done

Answer 13

examine grossly for quality of smear, anemia, autoagglutination

Question 14

After examining the slide grossly what is done

Answer 14

evaluate on low (10-20x) then high/oil (50-100x) power

Question 15

big clumps of platelets, large cells, microfilaria and leukocyte inclusions can be seen in what part of the peripheral blood film

Answer 15

feathered edge (rainbow region)

Question 16

where should you count on peripheral blood film

Answer 16

monolayer, middle between the feathered edge and the base where the RBC are spread out and WBC are easy to see

Question 17

__ is the first part of the blood film examined on low power

Answer 17

feathered edge (look for platelet clumps and microfilaria) do not use for counting!

Question 18

__ in the feathered edge are excessively spread and appear larger than they should, a lot of cells are also smudged here

Answer 18

leukocytes

Question 19

RBC in the feathered edge are completely flattened and lack a central pallor which mimic __, abnormal shapes are hard to ddx in this area

Answer 19

spherocytes

Question 20

what 4 things do you look for in the monolayer

Answer 20

1. platelet estimate
2. WBC estimate and differential
3. morphologic eval of ALL cells
4. data validation

Question 21

The coverslip method makes one big __ layer

Answer 21

monolayer

Question 22

in the __ layer about on 10x field behind the feathered edge the RBC are spearated or barely touching/not overlapping and the WBC are uniformly distributed

Answer 22

monolayer

Question 23

First step to systematic blood film eval is

Answer 23

view on low power in a good area to confirm cell counts, assess dom WBC, and look for “big” things

Question 24

leukocyte clumping is called __, automated WBC count falsely decreased by this

Answer 24

leukergy

Question 25

most machines won’t report __ such as the “big blue uglies”

Answer 25

atypical WBC (BBU are immature lymphocytes)

Question 26

On high power look for WBC and Platelet #/morphology and what 5 RBC things (only a human can do these things!!!)

Answer 26

1. arrangement
2. size
3. shape
4. color
5. inclusions

Question 27

Normal min amount of platelets/100x field in dogs and cats

Answer 27

7-10

Question 28

to estimate platelet count

Answer 28

multiply the average # of platelets for 10 fields then multiply by 20,000/mcL

Question 29

large platelets suggest __ but can be normal for

Answer 29

BM production

normal: felids and cavalier king charles spaniels (macrothrombocytopenia is normal for these)

Question 30

how many WBC should be counted on high power for a WBC differential

Answer 30

200

Question 31

what 4 morphological features of WBC are looked for on high power (only a human can do these!!!!)

Answer 31

1. neutrophil - left shift or toxicity
2. lymphocyte and monocyte reactivity
3. parasites
4. atypical or neoplastic cells

Question 32

to estimate WBC

Answer 32

on 100x: average # (at least 10 fields) x 10,000 = WBC/mcL

Question 33

if using an objective other than 100x how do you estimate WBC

Answer 33

average #wbc x Square of the objective power used to do the count. (for 100x = 10,000)