T6: Clinical Pathology Procedures

Question 1

Why perform clinical pathology tests?

Answer 1

• Detect disease, which may be clinical or subclinical disease
• Aid in diagnosis
• Monitor treatment success/failure and tailor or modify treatment according to response
• Monitor disease progression
• Aid in prognosis
• Post-mortem analysis

Question 2

What are we actually testing?

Answer 2

• Cells: number and morphology (age, health, activity)
• Fluids: volume, pH, composition

Question 3

What kind of tests do nurses perform?

Answer 3

• Histology/histopathology tests
• Cytology tests
• Haematology tests
• Fluid analysis
• Biochemistry tests
• Parasitology tests
• Microbiology tests
• Immunology tests
• Endocrinology tests

Question 4

What is an SST tube?

Answer 4

serum separation tube

This plain tube contains a blob of gel which seals the clot from the serum during centrifuging so you don’t need to remove the serum.

Question 5

What is an EDTA (pink or purple topped) tube used for?

Answer 5

for most blood tests, especially where red and white blood cells are measured.

Question 6

what is a Lithium heparin (Green topped tube) used for?

Answer 6

blood biochemistry tests. The tubes are centrifuged to separate blood cells from plasma.

Question 7

What is a Fluoride oxalate (Yellow or grey) tube used for?

Answer 7

to measure blood glucose levels. The mixture of sodium fluoride and potassium oxalate preserves blood cells so that the red cells can’t use up the glucose.

Question 8

What do tissue sample jars contain to preserve tissue?

Answer 8

formalin

Question 9

A sample label should list…?

Answer 9

• Animal’s name or Identification Number
• Owner’s name
• If a production animal, then an owner PIC code must be on the form
• Date and time of collection
• Veterinarian’s name and/or Name of Veterinary Clinic
• Type of specimen and method of preservation
• Test required

Question 10

A laboratory submission form should contain..?

Answer 10

• sample label details
• details of your veterinary clinic (sometimes with an ID number),
• the site of sample collection,
• and a case history including symptoms, findings, previous lab test results and any medications or treatments.

Question 11

How should whole blood be stored?

Answer 11

in an appropriate tube, and refrigerated for up to 3 days

Question 12

How should serum be stored?

Answer 12

Serum can be separated and stored in a separate tube. It can be stored at room temp for up to 24 hours, refrigerated for up to 4 days, frozen for a week or placed in deep freeze for several weeks or months.

Question 13

How should a urine sample be stored?

Answer 13

Urine should be tested within 30 minutes at room temperature or stored in the refrigerator in a dark container for up to 3 hours.

Question 14

How should a faeces sample be stored?

Answer 14

at room temperature for up to 3 hours, or stored in the refrigerator for up to 3 days (in a suitable container!)

Question 15

How should microbiology samples be stored?

Answer 15

• stored correctly to prevent microbial death or microbial overgrowth.
• Always check with your vet or laboratory technician for specific microbiology testing procedures.
• Bacterial swabs should be stored as transport (trans) swabs which are impregnated with culture media to prevent samples drying out, and stored in the refrigerator before transporting to the laboratory for culture and analysis.

Question 16

How should you pack a sample for transport?

Answer 16

• the specimen is packed into the first container, with cushioning material to prevent breakage and absorbent material in case of leakage.
• Always ensure the specimen is well sealed.
• this is then placed inside a waterproof container eg a plastic bag, along with the submission form
• the final container is the sturdy transporting container, for example a cardboard box or tube, or a Styrofoam cooler.

Question 17

The outer transport container of a sample should be labelled with…?

Answer 17

• a biohazard label
• identification of the material being transported
• the name, address and phone number of the receiving laboratory
• the name, address and phone number of your clinic (the sender) and the date
• any additional requirements eg consignment note, or hazardous goods stickers.

Question 18

clinical pathology in-house testing equipment commonly includes..?

Answer 18

• Microscopes
• Stains
• Centrifuges
• Test kits
• Refractometer
• Glucose meter
• In-house biochemical analysers
• In-house blood cell counting machines
• Incubator
• Bunsen burner
• Refrigerator/freezer
• Sample collection equipment and disposables

Question 19

Describe how you would set up a microscope

(answer is long explanation -try to simplify if possible)

Answer 19

• Sit comfortably, adjust the inter-ocular adjustments to suit your eyes
• Have the mechanical stage at its lowest position.
• Place the prepared slide onto the stage and lock it into position.
• Check the light is at its lowest power setting before switching it on.
• Make sure the lowest power objective (x4) is in position.
• Switch on the microscope and gradually turn up the light.
• Using the mechanical stage knobs move the slide until you can see light shining up through the condenser and through the object on the slide.
• Slowly raise the stage using the coarse focus knob until the specimen on the slide comes into focus.
• Swing the next power objective (x 10) into position and by using ONLY the fine focus knob turn it gradually until the specimen comes into focus.
• Once the 10X objective is in focus move up to the 40X lens and repeat the procedure only using the fine focus knob.
• Close the iris diaphragm down a bit to cut out some of the light coming up through the slide to make the slide easier to see.

Question 20

Find a picture of a microscope and label the parts

Answer 20

…. see moodle page

Question 21

For what focus is immersion oil used with a microscope?

For what focus is immersion oil never used?

Answer 21

• immersion oil is to be used with 100X objective
• NEVER to be used with 40X objective

Question 22

the course focus knob should only be used with ….. power objectives

Answer 22

low power objectives

Question 23

When using a microscope, you should always begin with the low power objectives and move up from there.

T or F?

Answer 23

T

Question 24

high dry magnification (x400) is usually enough to see most specimens clearly, however for blood cell identification and looking at bacteria you will need to use the oil immersion lens.

this is a statement and not a question just need to read :)

Answer 24

meow

Question 25

When finished using a microscope, you should:..?

Answer 25

• Always remove all traces of immersion oil when finished, as the oil will eat away at the glue holding the lenses in place inside the objectives
• Turn light to zero
• Turn off light to prolong bulb life as internal light sources can quickly overheat
• return stage to lowest setting
• return to lowest power objectives
• cover eye pieces with caps (if supplied)
• cover with dust cloth

Question 26

What solution should you clean a microscope with?

Answer 26

90% alcohol or lens cleaning solution

Question 27

What does a refractometer measure and how does it do this?

Answer 27

• measure the total plasma protein in a blood sample and urine specific gravity.
• does this by measuring concentrations of water soluble fluids – urine, blood plasma, milk, other bodily fluids
• It measures the speed light passes through a liquid (the refractive index)
• The denser the liquid, the slower light will travel through it and the higher is the refractometer reading

Question 28

What does the left, right and middle of the refractometer measure?

Answer 28

• left = total plasma protein
• right = urine specific gravity
• middle = refractive index for calibration

Question 29

How should you store and clean a refractometer?

Answer 29

Always keep it in its padded box when not in use – avoid knocks, and keep out the dust and hair.
Cleaning after every use –

Use soft lens tissue to wipe liquid off the glass slope
Wipe gently with lens tissue soaked in distilled water
Do not scratch!

3. Calibration – do this once a week to ensure equipment readings are accurate

Place a drop of distilled water on the glass slope
Read the RI scale in the middle – it should read 1.000

Question 30

How should you use a centrifuge?

Answer 30

• Place the sample in an appropriate container
• Load the centrifuge making sure it is balanced (a tube filled with water to the same volume as the sample can be used in the opposite bucket).
• Lock down the safety lid
• Set the revolutions and timer appropriate for the sample
• spin urine at a slower setting to avoid breaking elements such as crystals
• Allow the centrifuge to stop spinning completely before lifting the lid to retrieve the sample.
• Handle the sample carefully to prevent the sediment remixing.

Question 31

List the functions of a blood analyser machine

Answer 31

• Whole blood analysers - for performing blood counts and differentials
• Plasma or serum analysers – for analysing the biochemical components of the plasma/serum
• Specific chemical analysers – for example, testing for hormone levels (eg thyroid hormone; cortisol)
• Electrolyte level analysers
• Blood gas analysers

Question 32

Describe how you would collect blood from an animal

Answer 32

• prepare equipment
• restrain animal
• clip area (neck or forearm)
• scrub area aseptically
• hold up vein
• insert needle w/ bevel pointing upwards
• once bevel of needle enters vein lumen, apply suction
• once adequate v collected, remove needle and apply pressure to area
• transfer to sample tubes

Question 33

What is PCV and how is it measured?

Answer 33

• Packed Cell Volume aka haematocrit
• % of RBC in whole blood
• Use blood directly from the animal’s vein or blood collected in EDTA to fill a capillary tube (microhaematocrit tube) ¾ full
• Plug the end with plasticine or the special clay Cristaseal
• Spin tube (plasticine-filled end outermost) in centrifuge for 5 mins at 8000 rpm.
• Read the result - measure the amount of RBC as a percentage of the total blood.

Question 34

What does a low PCV mean?

What does a high PCV mean?

Answer 34

• low = (too few RBC) may mean the patient is anaemic eg to due haemorrhage or haemolysis
• high = (too many RBC) can mean dehydration, shock or disease.

Question 35

What is TPP, what does it measure, and how is it measured?

Answer 35

• Total plasma protein
• Measured using refractometer (same as urine specific gravity)
• includes albumin and larger proteins called globulins. Included in the globulins are antibodies which are protein molecules

Question 36

What does a high TPP indicate?

What does a low TPP indicate?

Answer 36

• high = dehydration or inflammation and paraproteinemia
• low = kidney, liver or gastrointestinal disease or with over-hydration, or post surgery can mean that the patient is losing protein, severe congestive heart failure (with edema), protein-losing nephropathy, protein-losing enteropathy, hemorrhage, burns, dietary protein deficiency, malabsorption, and some viral conditions (especially in horses).

Question 37

What is a blood smear used for?

Answer 37

To view:

• cell type,
• age of the cells,
• blood parasites
• blood cell pathology
• cell numbers.

Question 38

At what angle should the slide be when performing a blood smear

Answer 38

30 degrees

Question 39

How do you use a DiffQuick stain?

Answer 39

• “1” - fixative, clear light blue
• “2” - red stain
• “3” - blue/purple stain
• “4” - wash, distilled wate
• 15 second dips in each, rinse, dry, view

Question 40

What is an activated clotting time test used for?

normal cat clotting time?

normal dog clotting time?

Answer 40

• used to look for clotting defects, eg with rat bait (warfarin) poisoning or some snake bites, and sometimes when the vet suspects a clotting disorder.
• Dog’s blood should clot within 60-110 seconds,
• cat’s within 50-75 sec;
• anything greater than 2 minutes is considered abnormal.

Question 41

List the various ways of collecting a urine sample

Answer 41

• voided sample (direct catch in kidney dish)
• by manual compression of bladder,
• by catheterisation
• by cystocentesis (hypodermic needle and syringe placed into bladder through the abdominal wall).

Question 42

A gross examination of urine involves checking: ..?

Answer 42

• turbidity
• colour
• ease and frequency of micturition
• odour
• volume

Question 43

Urine reagent strips (pH strips) measure what? How long should it take to react?

Answer 43

• 60 seconds for full reaction
• glucose, ketones, bilirubin, protein, nitrite, blood, leucocytes and pH