Pre-Analytics Flashcards
What is a variable?
A factor that’s going to affect the outcome of test results & patient care
List 4 things that can affect how you choose a suitable venipuncture site?
- hematoma
- Edema
- Burns
- Scars
- Skin Conditions
- Occluded Veins
- Sclerosis
- Previous Mastectomy
- Tattoos
- IV Line
What can affect the success of a collection?
> Tourniquet time
Site cleansing
Blood flow
Defective supplies
Technique
Veins collapsing or rolling
What tests are affected by Lipemia?
electrolytes
LDH
hemoglobin
bilirubin
magnesium
- Ammonia
- Magnesium
- Lipase
- PTH
- Electrolytes
- TDM
Icterus samples affect which tests?
(Bilirubin in the cell)
Magnesium, Cholesterol,
Total Protein
- Lactate
- Cortisol
- Vitamin B12
- Ferritin
- Free T4
- PTH
- Ammonia
What are the 2 most common errors with Arterial Blood Gas samples?
Not storing on ice
Not delivering within 5-10 minutes
What is the forgiveness time for therapeutic drugs?
± 10-15 minutes
Know your special collections
What tests need to be kept on ice after venipuncture?
Ammonia
Homocysteine
What tests need to be kept warm after venipuncture?
Cold agglutinin
Cryoglobulin
How long do SST tubes need to sit before centrifuge?
3o minutes at room temp
How long do Lavender tubes need to sit before centrifuge and at what temp?
Refrigerate
spun within 4 hours at the lab
before that to give adequate time for lab
What are common issues faced in transportation of samples?
Time
Temperature
Light
What causes hemolysis?
- tourniquet left on or too tight (hemoconcentration)
- shaking tube
- alcohol not being dry
- improper storage or transportation
- tube unspun for too long
- incorrect needle
- incorrect volume for tube drawn
Hemolysis affects which tests most?
Potassium
LDH, AST, PTT
What causes icterus?
liver issues - viral, alcoholism, gallstones, cirrhosis, parasites
- hemolytic anemia
How can you eliminate contamination during a urine sample?
a midstream catch
Where is the most common place to store urine for preservation?
a refrigerator
If a urine sample is left overnight at room temperature, what changes can happen?
decrease in glucose and ketones
What are simple instructions for an FIT (Fecal Immunochemical Test) test?
- Place paper tissue between toilet seat lid and bowl
- Do your business
- Collect sample using grooves on the sample stick at the top of the sample tube
- Place back in the tube and twist closed
- Place in the ziplock bag provided and store in a refrigerator
Helicobacter Pylori Urea Breath Test steps are:
- Fast for 4 hours before your test:
-Do not smoke or eat anything, no fluid one hour before the test - Provide a breath sample
- Drink a lemon-lime solution
- Wait 30 minutes (do not smoke, eat, or drink during this time)
- Provide a second breath sample
For semen collection can the sample be brought in an hour after collection?
No.
Ideally 10-15 minutes after, but it can be 30 minutes after
What is the purpose of a centrifuge?
separation
to spin samples and separate cells
Can you put blood down the dirty sink?
No.
It has to get disposed of properly in a biohazard container
When would you use a fume hood?
When using chemicals you don’t want to inhale
What do you use an incubator for?
growing samples of microorganisms or bacteria
What is the major difference between a Fume Hood and a Biological Safety Cabinet?
The Biological Safety Cabinet is not vented to outside because the air goes through a hepa filter.
The Fume Hood is vented to outside.
How often does lab equipment need to be maintained/calibrated?
Every 6 months usually
Yearly for a full service
Which fecal test uses a chemical indicator/reaction method?
Fecal Occult Blood Test (FOB)
Which fecal test uses an antibody method?
Fecal Immunochemical Test (FIT)
What is a refrigerator’s temperature kept between?
2º - 8º C
Name the 4 groups microorganisms are grouped into
Bacteria
Virus
Fungi
Parasites
Name 2 things bacteria do for humans that ISN’T harmful
- Provide us with vitamin K
- Assist our digestive system
- Protect our body surface from colonizing
pathogens - Part of vaccines
- Part of certain food processing
- Nitrogen fixation assists soil fertility
- Decompose organisms
What is the basic shape of Cocci (Coccus)?
Spherical
What is the basic shape of Bacilli (Bacillus)?
Rod-Shaped
What is the basic shape of Spirilla (Spirillum/Helical)?
Spiral Shaped
What are the 3 major nutritional needs for bacterial growth?
Carbon
Nitrogen
Energy (ATP)
What temperatures are cultures routinely grown at?
35°-42°c
What are anaerobe bacteria?
Bacteria that are unable to grow in the presence of oxygen
What are aerobe bacteria?
Bacteria that needs oxygen to grow
What are capnophilic bacteria?
Bacteria that grow better with a carbon dioxide enriched atmosphere
An infection is dependant on what outcomes?
Size - of the infecting dose
Site - of infection
Virulence - of organism
Speed & Effectiveness - of immune response
Accurate ID, Timeliness and Treatment
What is an ectoparasite?
Parasite that lives on external surfaces
Bacteria are treated with?
Antibiotics
What type of plate differentiates based on HEMOLYSIS?
BAP
Blood Agar Plate
What is the difference between Bactericidal antibiotics and Bacteriostatic antibiotics?
Bactericidal KILLS bacteria out right by directly attacking the cell and injuring it.
Bacteriostatic STARVES the cell of nutrients, stopping it from dividing and attacking while letting the immune system attack the bacteria
What colour is Gram positive?
Purple
What colour is Gram negative?
Pink
Should a plate be refrigerated before inoculation?
Yes, to prevent bacteria from growing
What is differential media?
contains specific ingredients/chemicals that allow the observers to distinguish between species
Blood agar is a differential medium that distinguishes bacterial species by their ability to break down red blood cells
What is this streaking pattern for?
Fluid
What is this streaking pattern for?
Urine
What is this streaking pattern called?
1/1/1
What is this streaking pattern called?
5/3/1
What is the order of Gram Staining?
Primary Stain - Crystal Violet
Mordant - Iodine
Decolorizer - Alcohol/Acetone
Counterstain - Safranin/Basic Fuchsin
Cells on Slide!
How does a MAC (MacConkey) agar plate work?
It is selective and differentiates by LACTOSE FERMENTATION
selective for gram negative
selectively isolate bacilli usually found in the intestinal tract
How does a BLOOD AGAR plate work?
It’s non selective and differentiates
by HEMOLYSIS
How does a Chocolate AGAR work?
It’s non selective and the red blood cells have been lysed to aid in precise organism growth
commonly used to grow respiratory bacteria
What is the KIRBY BAUER disc method?
To test the effectiveness of antibiotics on a specific microorganism
If the organism is susceptible to a specific antibiotic, there will be no growth around the disc containing the antibiotic
If the organism is resistant, there will be growth up to the disc
What is an E Test?
Consists of a predefined gradient of
antibiotic concentrations on a plastic strip to determine the Minimum Inhibitory Concentration (MIC) of antibiotics, antifungal agents and antimycobacterial agents
What are the 3 different types of sample taking methods?
Swab
Blood
Infected Tissue or Fluid
How can we treat a virus?
treatments can only help with symptoms while the immune system fights off the virus
VACCINES are the best preventative method
How long should you leave the Primary Stain on for?
1 minute
Crystal Violet
How long should the Mordant stay on for?
1 minute
Mordant
How long should the Decolorizer stay on for?
Just a quick second and rinse right away
Alcohol or Acetone
How long does the Counterstain stay on for?
1 minute
Safranin or Basic Fuchsin
Thick smears are to determine the presence/absence of what?
Parasites
Qualities of a good thick smear are…
About the size of a dime
Print can be read through it
A Thin smears purpose is to…
separate and count the % of parasitaemia (parasites in the blood)
A quick stain takes how long?
The whole process is 1 minute
Giemsa or Wright
Name 2 disadvantages to point of care testing
quality of results
lack of proficiency
possible errors with integration of data
inappropriate use
maintenance on QC (Quality Control)
costs much higher
Pre-analytical errors with point of care include…
not wiping away first drop
excessive squeezing
not sanitizing
under or over filling the strip
incorrect patient ID
incorrect manual data entry
forgetting QC
Automation ADVANTAGES include…
quicker than manual
cheaper b/c performed in bulk volume
higher precision & accuracy
Lab can handle more
tech can multitask
Automation DISADVANTAGES include…
Equipment can malfunction
technology issues
maintenance
Three reagents in a Wright’s stain are…
a) Alcohol - Methanol - Fixative
b) Methylene Blue - Basic Dye - stains acidic elements
c) Eosin - Acidic Dye - Stains bases elements
What is the fixative/mordant found in Gram’s stain?
Iodine
A blood agar plate differentiates bacteria based on what?
hemolytic properties
Define bacteriostatic
prevents the growth of bacteria
What is bactericidal?
kills bacteria
What is a centrifuge?
A machine with a RAPIDLY ROTATING container that applies centrifugal FORCE to its contents, typically to SEPARATE FLUIDS of different DENSITIES
Calibrated every 3 months
What does it mean to decontaminate?
to remove, neutralize, or destroy any harmful substances
Define pathogen
An organism causing disease to its host
What kind of infection happens when the bacteria is already present in your body?
a) Epidemic
b) Exogenous
c) Endogenous
d) Pandemic
c) Endogenous - proceeding from within; derived internally
Epidemic - occurring widely in a community at a particular time
Exogenous - growing or originating from OUTSIDE an organism.
Pandemic - a widespread occurrence of an infectious disease over a whole country or world at a particular time
Gram positive have a _____ wall
thick
Gram negative have a _____ wall
thin wall
with a lipid layer
