Basic Methods 1 & 2 Flashcards
______ is vital in the lab’s first step to reporting accurate and reliable results
Proper patient specimen blood collection
Necessary things to achieve accurate and reliable results in the hematology laboratory
- knowledge of equipment & supplies
- technical skills
- strict attention to patient & specimen ID
- awareness of & adherence to institutional safety requirements
- proper specimen transport techniques
the skill, the good judgment, and polite behavior that is expected of a person who is trained to do the job well
Professionalism
2 skills necessary for phlebotomists
- good interpersonal skills
- good communication skills
True or False
Lab results and personal info about a patient can be discussed with other medical technologists on duty
False, should not be discussed unless relevant to the patient’s care
True or False
All body fluids are treated as biohazards except the plasma as it contains nutrients
False, no exceptions
True or False
Disposable syringes can only be reused twice
False, should not be reused
3 kinds of samples used in the hematology lab
- whole blood
- plasma
- serum
Majority of biochemical & blood bank test are performed on ____
Serum
Main coagulation difference between serum and plasma
Presence of fibrinogen
How long and at what temp should you let whole blood stand to obtain the serum?
30 mins - 1 hour at room temp
How long and at what speed should you centrifuge the clotted blood?
10 mins at 3000 rpm
At what temperature should serum be stored in relation to the delay in testing?
- 4°C if to be tested after 30 mins-1 hr
- -20°C if to be tested after more than 1 hr
How long can serum be stored at -20°C?
3 months
True or False
Frozen specimens should be thawed on the bench or in a water bath at 60°C, then inverted several times to ensure homogeneity
False, room temperature
How does one defibrinate whole blood?
Before the blood clots, place it in a receiver (e.g., conical flask) containing a central glass rod onto which small pieces of glass capillary/glass beads/paper clips have been fused. Blood is then whisked around the central rod through moderate rotation of the rod.
How long does a patient need to fast if his/her blood is to be collected for FBS and cholesterol?
6 and 12 hrs, respectively
What is the effect of smoking on the blood?
Increases neutrophils
Which pre-collection factor increases a patient’s platelet count?
Physical activity (within 20 mins)
How does stress affect the blood?
Increases WBC count
True or False
WBC count is highest during mornings and decreases towards the afternoon.
False, lowest in the mornings and increases to mid afternoon
How does posture affect the substances present in the blood?
Enzymes, proteins, calcium, and iron increase with changes in position
What happens when tourniquet pressure is prolonged?
Hemoconcentration (increase in total protein)
What causes hemolysis during blood collection?
Excessive negative pressure when drawing blood with a syringe
How can insufficient anticoagulant affect specimens during post-collection?
Causes agglutination
Which post-collection error causes dilution of the blood sample?
Excess anticoagulant
How long does it take for blood samples to be deemed unusable?
2 hrs.
Which type of blood is used when large quantities of blood is needed?
Venous blood
True or False
Arterial blood is necessary for most tests that require anticoagulation
False, venous blood
Why are anticoagulated blood not used for peripheral blood smears?
Anticoagulants produce changes in platelets that may cause clumping and distort WBC that make identification difficult.
When is capillary peripheral blood usually used?
Used usually in infants less than 1 year old or when it is impossible to obtain venous blood
What are the disadvantages of using capillary peripheral blood?
- liable to give erroneous results
- greater likelihood of contamination
- greater risk of disease transmission
True or False
Capillary blood is free flowing and can be arteriolar in origin
True
Which type of blood has a higher packed cell volume, red cell count, and hemoglobin?
Capillary blood
Why does capillary blood have a lower platelet count compared to venous blood?
Due to adhesion of platelets at the site of skin puncture
the release of hemoglobin from ruptured red cells into the plasma
Hemolysis
Hemolyzed red cells act as ________ in activating plasma clotting factors
Tissue thromboplastin
True or False
When obtaining capillary peripheral blood, the puncture site should be squeezed/milked to allow the blood to flow
False, do not squeeze puncture sites!
3 Methods of Venous Blood Collection
- Butterfly infusion set
- Evacuated tube system
- Syringe method
the method of choice for small fragile or damaged veins
Syringe method
True or False
Blood should never be poured from one tube to another since tubes can have different additives or coatings
True
With regards to needles, the larger the gauge number, the ______ the needle bore
Smaller
additive present in yellow tubes for blood cultures
Sodium polyanethol sulfonate (SPS)
True or False
Green tubes with heparin come after lavender EDTA tubes in the order of draw
False, before
additive present in light blue tubes
Sodium citrate
CLSI
Clinical Laboratory Standards Institute
CAP
College of American Pathologists
JC
Joint Commissions
recommended patient safety goals requirement
Minimum of 2 patient identifiers when collecting blood
Where should the tourniquet be applied?
3-4 inches above the antecubital fossa
At what angle should the needle be positioned in relation to the vein?
15-30°
venipuncture technique used for children under 2 years of age
Dorsal hand venipuncture
advantage of dorsal hand technique over heel stick method
- more blood can be collected
- less chance of hemolyzing the sample
- less chance of contaminating the sample w/ tissue fluid
Methods of blood collection for infants
- cord blood
- external jugular vein procedure
- skin/dermal puncture
Where is cord blood obtained from?
The umbilical cord
Drawing excessive amounts of blood from small infants can cause _____
Anemia
Dermal punctures are preferred over venipuncture when patients:
- are burned or scarred
- are receiving chemotherapy
- have thrombotic tendencies
- are geriatric
- have very fragile veins
- are obese
- are apprehensive
- require home glucose monitoring and point-of-care tests
Composition of Capillary blood
- venous blood
- arterial blood
- interstitial fluids
- intracellular fluids
True or False
Capillary blood composition more closely resembles arterial blood than venous blood
True
When performing dermal puncture, CLSI recommends that the incision depth should not exceed _____ in a device used to do heel sticks
2 mm
True or False
The depth of puncture is more critical than the width of the incision to produce adequate blood flow
False, less important
Where is the major vascular area of the skin located?
Dermal subcutaneous junction
Where is the dermal subcutaneous junction located in newborns?
0.35 - 1.6 mm below the skin
Where is the dermal subcutaneous junction located in adults?
3 mm below the skin
With dermal puncture, sufficient blood flow should be obtained from incision widths no larger than ______
2.5 mm
Factors on which type of lancet should be used during skin puncture
- age of patient
- amount of blood sample required
- collection site
- puncture depth
amount of blood collected by microhematocrit tubes
approx. 50 - 75 µL
additive present in some microhematocrit tubes
Ammonium heparin
chemicals contained in a heel warmer
- sodium thiosulfate
- glycerin
True or False
After performing the skin puncture, every drop of blood must be collected in order to obtain a sufficient amount for testing
False, the first drop should be wiped away
Why should you not collect blood from the side of a mastectomy?
In mastectomy, the lymph nodes are also removed so there would be a greater chance for an infection to occur.
the ideal site for skin puncture on infants younger than 1 year
Heel
What areas of the heel are acceptable for skin puncture in infants?
The medial and lateral areas of the plantar surface of the heel
Why are finger punctures not performed on infants younger than 1 year?
Their fingers do not contain enough tissue to prevent contact with bone
Why should the finger puncture be perpendicular to the ridges of the fingerprint?
So that there would be a greater chance for the wound to easily open up and more blood can be collected
Why should the finger puncture be off center?
The tips and sides of the finger only contain half the tissue mass of the center, increasing the possibility of bone injury
Why are the 3rd and 4th fingers preferred for finger puncture?
They have the least problems
- thumb has calluses
- index has increased nerve endings
- pinky has decreased tissue
How does warming affect blood flow?
Warming dilates the blood vessels, therefore increasing arterial blood flow
temperature of water during warming
42°C
Aside from warming, how can one increase blood flow to the finger or heel?
By massaging the area
How do air bubbles in the tubes affect blood samples?
Air bubbles limit the amount of blood that can be collected per tube and interfere with blood gas determinations
How does one prevent the introduction of air bubbles in tubes?
Hold capillary tubes and micropipettes horizontally while being filled
Analogy
Pink/lavender cap: CBC
Light/dark green: ____
- chemistry K+
- glucose
Main source of error for skin puncture
Hemolysis
Causes of Hemolysis
- failure to dry site after cleaning
- very deep puncture
- failure to wipe away first drop of blood
- vigorous massaging of area
- air bubbles
Modes of action of anticoagulants
- removing calcium by adding oxalates, citrates, & EDTA
- inactivating thrombin & thromboplastin by adding heparin
- removing fibrin by defibrination
Why should EDTA not be used as anticoagulant when K assay is to be performed?
Potassium salts of EDTA interfere with K assay
What additive should not be used when BUN is to be performed on a sample?
Ammonium oxalate
What is affected if oxalates are used as anticoagulant on samples for peripheral smears?
White cell morphology
anticoagulant of choice for prothrombin time & partial thromboplastin time
Sodium citrate
Which clotting factor is relatively stable in citrated blood?
Factor V (proaccelerin/labile factor)
anticoagulant of choice for platelet counts & platelet function tests
EDTA
optimal concentration of EDTA
1.5 mg EDTA per ml blood
What is the effect of excessive amounts of EDTA on the blood sample?
Excessive amounts of EDTA induces red cell shrinkage and causes a decrease in hematocrit and ESR values
anticoagulant of choice for osmotic fragility test
Heparin
effect of potassium oxalate on RBC
Shrinkage
effect of ammonium oxalate on RBC
Swelling
