Phlebotomy

• What is phlebotomy?

  Phlebotomy is the puncture of a vein (venipuncture) for the purpose of drawing blood for medical testing or donation.
• What is the first step in the process of phlebotomy?

  The patient is placed in the supine position.
• What should the patient do with their hand during phlebotomy?

  The patient makes a fist with their hand.
• Why does the phlebotomist disinfect the site area?

  To prevent infection at the venipuncture site.
• What concentration of alcohol is used to disinfect the site area?

  70% alcohol swab.
• What is the purpose of placing a tourniquet around the patient's upper arm?

  It makes the veins pop out more, making it easier to insert the needle correctly.
• How far above the venipuncture site is the tourniquet placed?

  
  

  3 to 4 inches above the venipuncture site
• How does the phlebotomist anchor the selected vein?

  By using their thumb and index finger.
• At what angle is the needle positioned during insertion?

  At a 30 degree angle.
• Where is the needle inserted during phlebotomy?

  Into the venipuncture site in the antecubital fossa.
• What happens after the needle is inserted?

  Blood flows into the test tube.
• What should be done after sample collection?

  The tourniquet is released before withdrawing the needle.
• What is done to the area after withdrawing the needle?

  The area is bandaged and pressurized until the bleeding stops.
• Where is the needle discarded after the procedure?

  In the sharps container.
• What should be done with gloves after the procedure?

  Gloves are removed and hands are washed.
• How is the sample prepared after collection?

  By inverting the tube 8-10 times to mix the sample with the tube additives.
• What information is included on the sample label?

  The patient's full name, patient ID, date and time of sample.
• Why is the sample labelled in the presence of the patient?

  For confirmation of the patient's identity.
• Where is the sample sent after labeling?

  To the lab for testing.
• How does a needle draw blood into a test tube?


  The sample tube is under a vacuum - once the needle is in the vein there is a negative pressure so the tube acts as a suction for the blood
• what must a patient do before a blood test?

  the patient must fast (to be in a resting state) to give the most accurate results

  the patient must be well hydrated with water (retains more fluid in the veins which makes them more plump) to make it easier for the phlebotomist to find a vein and venipuncture
• what types of blood tests are there?

  full blood count - checks overall health, identifies abnormalities

  coagulation - tests the function of clotting proteins

  reticulocyte count - measures number of immature RBC in the bone marrow

  bone marrow aspiration/trephine biopsy - piece of bone marrow removed, shows if the bone marrow is making normal amounts of blood cells
• what is the nature of blood in vivo?

  naturally anticoagulated by the endothelium

  cells are stable and functionally active

  homeostasis maintains stable biochemical levels

  balanced O2 and CO2 levels

  stable pH (7.35-7.45)

  constant temperature and metabolism at 37 degrees Celsius

  active immune surveillance
• what is the nature of blood in vitro?


  Coagulates unless anticoagulants added

  Cells degrade (impacted by external factors)

  Biochemicals degrade (needs immediate processing)

  Gas exchange stops - CO2 buildup alters pH

  Temperature varies and metabolism slows

  Immune response diminished, cells degrade
• what are the 6 colours of anticoagulant tubes?


  purple cap

  red cap

  light blue cap

  green cap

  grey cap

  gold/yellow cap
• what is the purple anticoagulant and its role?

  EDTA

  binds to calcium ions (essential for clotting) which prevents clotting and preserves blood cell morphology

  used for haematology tests like full blood counts and blood smears
• what is the red anticoagulant and its role?


  plain, no additive

  allows blood to clot so serum is leftover

  used in serology tests like testing for antibodies to see if a patient has been exposed to or infected by a virus or any other infectious pathogens
• what is the light blue anticoagulant and its role?

  sodium citrate

  binds to calcium ions and inhibits clotting factors but reversibly (reversible inhibition) so it restores the normal levels

  used to study coagulation factors
• what is the green anticoagulant and its role?


  lithium heparin

  acts as an anticoagulant by binding to and activating antithrombin which inhibits thrombin and other clotting factors

  used for plasma biochemistry tests, immunology tests and chromosome analysis
• what is the grey anticoagulant and its role?


  potassium oxalate/sodium fluoride

  potassium oxalate binds to calcium, sodium fluoride inhibits glycolysis

  used for blood glucose testing
• what is the gold/yellow anticoagulant and its role?


  serum separator tube (SST)

  contains a clot activator and a gel for serum separation

  used for serology tests, blood bank tests and serum chemistry tests
• list some sources of error that can happen in phlebotomy

  pre-analytical error e.g. patient prep issues

  technique error e.g. incorrect venipuncture

  specimen handling and transport error e.g. inadequate mixing

  post analytical errors e.g. delayed processing, improper storage

  communication error
• what are some determinants of specimen quality?


  pre-analytical e.g. patient prep like fasting and hydration

  analytical factors e.g. technique consistency

  biological variability e.g. age, sex, health conditions

  environmental factors e.g. temperature changes, light sensitivity

  contamination e.g. external contaminants
• what is a reference range?


  the set of upper and lower limits based on a group of healthy people
• what is a Gaussian distribution?


  the ‘normal’ distribution

  95% of results lie within 2 standard deviations of the mean

  results that lie within 2 standard deviations of the mean are used to define the ‘reference range’ range
• what are the intra individual sources of blood variation?


  time of blood sampling (circadian rhythm affects levels)

  posture (ambulant and supine)

  medications (affect chemical results)

  exercise (increases lactate conc and lowers pyruvate conc)

  menstrual cycle (variation in plasma iron conc, ovarian steroids and metabolites, pituitary gonadotrophins)
• what are some inter individual sources of blood variation?


  age (differences in plasma phosphate and alkaline phosphatase activity)

  ethnicity (differences in plasma cholesterol, protein, creatinine)

  gender ( differences in plasma conc, 24 hour urinary output, pituitary and gonadotrophic hormones, creatinine, iron, urate, urea)