automated analyzers

Question 1

What is the difference between a hematology (cytology) analyzer and a blood chemistry machine?

Answer 1

The hematology machines do a CBC utilizing a sample preserved with EDTA, Blood chemistry machines analyze serum or plasma for certain blood chemistries

Question 2

What are 3 advantages of using a machine rather than doing the diff by hand

Answer 2

a. Faster than doing a manual count
b. No operator bias
c. More reproducible counts more cells than manual

Question 3

Name at least 3 drawbacks of depending upon automated cytology machines alone

Answer 3

a. Clots, and large platelets can cause errors
b. Machine cannot pick up diagnostic changes in cell morphology
c. NRBC can also cause errors must do a manual blood smear to correct the WBC count

Question 4

What anticoagulant is used for samples in a hematology machine? In a blood chemistry machine?

Answer 4

EDTA; Lithium heparin-plasma

Question 5

Explain the difference between a rocker and a vortex mixer

Answer 5

Rocker- need to hand mix just before use
Vortex mixer- useful for breaking up microclots that are common in felines

Question 6

Explain how impedance is used to count cells and how the machine can tell an RBC from a WBC using this method

Answer 6

Cells pass through a charged aperture, disrupting the current, each interruption is counted, the length of interruption is proportional to size. Chemical lysing agents are also used to help differentiate the cells

Question 7

If you are collecting blood for a CBC to be run by an automated cytology analyzer, why would it be a good idea to make a blood smear? When should the smear be made? Why?

Answer 7

To pick up machine errors and to identify abnormal morphology; To correct a WBC count, NRBCs will cause an elevated WBS count

Question 8

What are the graphs called that are shown on the results screen? What does each dot represent?

Answer 8

Dot plots; Each dot in the plot represents a single cell as it is analyzed by the device

Question 9

Which part of the dot plot changes most from one species to another?

Answer 9

eosinophils

Question 10

What are doublets?

Answer 10

Doublets are two discreet red blood cells that are in close proximity to one another when they are examined by the laser beam. They are mapped as one event but counted as two cells

Question 11

what are RBC fragments?

Answer 11

Red blood cell fragments are portions of red blood cell membranes from broken cells. The particles have a similar size to platelets but refract light differently and are therefore located to the left of the platelet population. The red blood cell fragments are colored pink

Question 12

What is a uRBC?

Answer 12

The unlysed red blood cell (uRBC) population is composed of red blood cells that did not lyse prior to the white blood cell run. uRBCs are classified so they do not interfere with the leukocyte differential. The uRBC population is colored orange

Question 13

What are qualiBeads in the Lasercyte?

Answer 13

Each CBC5R tube contains a known quantity of standard-sized particles called qualiBeads. The analyzer evaluates the signal from the qualiBeads to determine if there are shifts in the beads’ scatter pattern. as a quality assurance check for each individual run. If the analyzer counts too few or too many QualiBeads, the sample run will be flagged to indicate a potential problem with that portion of the analysis. The qualiBeads population is colored gray

Question 14

Explain how to load the Lasercyte to run a sample

Answer 14

• 3 mL tube
• invert 8 times
• remix sample prior to testing
• place CBC5R tube in slot 2
• place sample in slot 1
• close lid and run

Question 15

Cat blood often has microclots – small clumps of platelets that we can’t see. What is the best way to break these up so that they don’t interfere with machine results?

Answer 15

Using a vortex mixer

Question 16

The results screen says “RBC 5.6 x 1012/L, WBC 10.6 x 109/L”. How many RBCs and WBCs would you find in a microliter of this sample?

Answer 16

RBC=5.6 X 1012/L X 1/L/106 X 1012/106 =5,600,000/ul WBC=10.6 X 109/L X 1/L/106ul X 109/106=10,600/ul

Question 17

Explain briefly how blood chemistry machines work

Answer 17

• Plasma or Serum is mixed with a reagent (chemical).
• Different reagents are used for each blood chemistry test.
• The chemical reaction between the chemical in the sample and the reagent produces a color change in the sample.
• The amount of color change is proportional to the amount of the chemical present in the sample.
• The machine measures the amount of color and calculates the amount of chemical (BUN, Alk Phos…) using that number.

Question 18

For the Catalyst blood chemistry machine, discuss the storage of testing supplies. Why shouldn’t you get the test slides out or open them until it is time to load the machine?

Answer 18

Test slides are stored in the refrigerator or freezer; If allowed to warm prior to loading, discard Once opened, they must be used within a short time or discard

Question 19

If testing can’t be done within an hour of drawing the blood, how should it be stored so blood chemistry tests can be run? What if it will be longer than 1 day?

Answer 19

tube must be spun down and serum/plasma removed and placed in a plain top tube; Freeze the plasma or serum

Question 20

When entering patient information into the hematology machine, what piece of info is important to get right so the results will be correct?

Answer 20

species

Question 21

Can you use samples that have been frozen for blood chemistry testing? For hematology testing?

Answer 21

yes; no

Question 22

When pipetting samples, where should the tip of the pipette be before releasing the button to aspirate the sample?

Answer 22

Seated well in the sample

Question 23

There are 2 reasons hemolysis can cause incorrect blood chemistry results. One of these is that the abnormal plasma color can interfere with the result. What is the other issue with hemolysis that causes abnormal chemistry results?

Answer 23

intracellular contents are spilled into the plasma