Lecture 2

Question 1

Why do we still need to look at blood films?

Answer 1

validate numeric data generated by the hematology analyzer

add valuable info that only a trained human can provide

Question 2

List 6 things that need to be validated in the blood film?

Answer 2

RBC quantity (RBC count, HCT, Hgb)
RBC indices (MCV, MCHC, RDW)
WBC count 
WBC differential
Platelet count
Platelet indices

Question 3

What 4 things can you add that only a trained human eye can provide?

Answer 3

RBC morphology (clues to cause of anemia)
WBC morphology ( shows whether or not there is inflammatory response or neoplasia)
platelet morphology
infectious diseases

Question 4

What 4 things are important in a blood film preparation?

Answer 4

1. Anticoagulated blood (EDTA tube)
   - invert tube at least 8 times before making smear
2. Fill tube to appropriate line
3. Prepare the film asap after collection
4. rapidly dry films to prevent air drying artifact (DO NOT heat fix)

Question 5

2 blood film smear techniques

Answer 5

Push film

Coverslip

Question 6

What is the name of the stain used for the fixative?

Answer 6

Diff Quik stain

Question 7

how long do you leave the smear in the fixative?

Answer 7

at least 2 min won’t hurt it to stay longer

Question 8

What stain is used for detecting reticulocytes and Heinz bodies?

Answer 8

New methylene blue

Question 9

Can you use tap water to rinse the slide

Answer 9

yes if it is the right pH/ if not need to use distilled

Question 10

true/ False

You need to wash with water in between stains

Answer 10

False - just let it drip on paper towel in between stains

Question 11

What results in a refractile artifact or moth eaten appearance?

Answer 11

Water artifact

Question 12

What does refractile artifact mean?

Answer 12

As you focus up and down on the cell the artifact flashes; in one plane of focus it may appear dark while in another one it may appear bright

Question 13

What is water artifact often mistaken for?

Answer 13

Red blood cell inclusion ie. parasite

Question 14

What 3 things can you evaluate from the blood smear grossly?

Answer 14

if the smear was appropriately made
if the animal is anemic
if there is autoagglutination

Question 15

What part of the blood film is too thick to evaluate?

Answer 15

base

Question 16

What part of the blood film do you look at to see platelets or parasites ie. big things?

Answer 16

the feathered edge

clumped platelets, large cells, microfilaria, leukocyte inclusions

Question 17

What part of the blood film is used to evaluate and count RBC and WBC’s?

Answer 17

the “counting area”

Question 18

What is seen in the feathered edge?

Answer 18

Clumped platelets
large cells
Microfilaria
Leukocyte inclusions

Question 19

What part of the smear do you evaluate first on low power?

Answer 19

feather edge to check for platelet clumps and microfilaria

Question 20

IF analyzer says you have a low platelet count (thrombocytopenia) what should you do?

Answer 20

go to the feathered edge to see if there is platelet clumping

Question 21

what do the RBC’s look like in the feathered edge?

Answer 21

completely flattened and lack central pallor, look like spherocytes. Abnormal shapes are difficult to recognize in this area

Question 22

What is evaluated in the monolayer on the blood smear?

Answer 22

Estimate platelet number
Estimate leukocyte number and differential count
Morphologic evaluation of all the cells
Data validation

Question 23

What happens when you place a coverslip on the blood smear?

Answer 23

Big things will appear on the periphery of the coverslip

Question 24

Where is the monolayer located on the blood smear?

Answer 24

one 10x field behind the feathered edge

Question 25

Why is the monolayer the optimal area for examination of cells

Answer 25

it dries quickly
cells are spread out and not disrupted
RBC’s are separated with little overlapping
WBC’s are also uniformly distributed

Question 26

What do you evaluate on the blood smear on low power?

Answer 26

Confirm cell counts
Determine the predominant WBC
Look for big things: platelet clumps, abnormal cells, microfilaria

Question 27

What WBC cell should be predominate in dogs, cats, and horses?

Answer 27

neutrophils

Question 28

What WBC will be predominant in birds and reptiles?

Answer 28

lymphocytes

Question 29

What animal species usually have clumped platelets?

Answer 29

cats

Question 30

What are clumps of WBC’s referred to as?

Answer 30

Leukergy

Question 31

What do you evaluate under high power on the blood film?

Answer 31

WBC number and morphology
RBC arrangement, size, shape, color, and inclusions, and validate numeric data
platelet number and morphology

Question 32

True/ False

It is okay to accept a low platelet count from an automated analyzer w/o confirming it on the blood film

Answer 32

FALSE! - there may be platelet clumping

Question 33

What is the bare minimum of platelets in dogs and cats?

Answer 33

7-10 per 100x field

Question 34

How do you estimate platelets counts?

Answer 34

determine average # of platelets per 100x field and multiply by 20,000/microliter

Question 35

What do large platelets suggest?

Answer 35

increased marrow production of platelets

normal for felids and Cavalier King Charles Spaniels

Question 36

True/False

the analyzer will still count large platelets

Answer 36

False

Question 37

How do you estimate the number of leukocytes in the smear?

Answer 37

Take the average # of leukocytes per 100x field after evaluating 10 fields and multiply by 10,000

Question 38

What 3 things do you do when evaluating platelets on the smear?

Answer 38

Evaluate number of platelets per 100x field (should be at least 7-10)
Estimate platelet count
Check for large platelets

Question 39

What 3 things do you do when evaluating leukocytes on the smear?

Answer 39

• Estimate leukocyte number per microliter
• Do a differential leukocyte count on 50x or 100x (look at 200 WBC’s and tabulate the type)
• Evaluate leukocyte morphology on 50x and 100x

Question 40

What do you evaluate neutrophils for?

Answer 40

left shifting and toxicity

Question 41

What do you evaluate lymphocytes and monocytes for?

Answer 41

Reactivity (will have more cytoplasm)