Blood Sampling

Question 1

Steps in blood sample collection?

Answer 1

1. knowledge of the equipment used in blood sample collection
2. use of the correct gauge of hypodermic needle to prevent haemolysis or abnormal results
3. the anatomical insertion site for venepuncture
4. the use of recommended laboratory collection tubes
5. patient–sample matching (i.e. labeling)
6. transportation conditions
7. interpretation of results for clinical management.

Question 2

Equipment required for blood sampling?

Answer 2

1. asterileglass or bleeding pack (collapsible) if large quantities of blood are to be collected
2. well-fitting, non-sterilegloves
3. an assortment of blood-sampling devices (safety-engineered devices or needles and syringes)
4. a tourniquet
5. alcohol hand rub
6. 70% alcohol swabs for skindisinfection
7. gauze or cotton-wool ball to be applied over puncture site
8. laboratory specimen labels
9. laboratory forms

Question 3

How do you prepare the patient?

Answer 3

1. Introduce yourself to the patient, and ask the patient to state their full name
2. Check that the laboratory form matches the patient’s identity
   i.e. match the patient’s details with the laboratory form, to ensure accurate identification
3. Ask whether the patent has allergies, phobias or has ever fainted during previous injections or blood draws.
4. If the patient is anxious or afraid, reassure the person and ask what would make them more comfortable.
5. Make the patient comfortable in a supine position (if possible).
6. Place a clean paper or towel under the patient’s arm

Question 4

How do you select the site?

Answer 4

1. Extend the patient’s arm and inspect the antecubital fossa or forearm.
2. Locate a vein of a good size that is visible, straight and clear.
3. The vein should be visible without applying the tourniquet
   - Locating the vein will help in determining the correct size of needle.
4. Apply the tourniquet about 4–5 finger widths above the venepuncture site and re-examine the vein

Question 5

What vein is best for blood sampling?

Answer 5

The median cubital vein lies between muscles and is usually the most easy to puncture
Note:
1. Under the basilic vein runs an artery and a nerve, so puncturing here runs the risk of damaging the nerve or artery and is usually more painful.
2. DO NOT insert the needle where veins are diverting, because this increases the chance of a haematoma.

Question 6

Hand hygiene + gloves?

Answer 6

1. wash hands with soap and water, and dry with single-use towels; or
   - if hands are not visibly contaminated, clean with alcohol rub – use 3 ml of alcohol rub on the palm of the hand, and rub it into fingertips, back of hands and all over the hands until dry.
2. After performinghand hygiene, put on well-fitting, non-sterilegloves.

Question 7

Disinfection of entry site?

Answer 7

1. Unless drawing blood cultures, or prepping for a blood collection, clean the site with a 70% alcohol swab for 30 seconds and allow to dry completely (30 seconds)
2. Apply firm but gentle pressure.
   - Start from the centre of the venepuncture site and work downward and outwards to cover an area of 2 cm or more.
3. Allow the area to dry. Failure to allow enough contact time increases the risk of contamination.
   Note:
   DO NOT touch the cleaned site; in particular, DO NOT place a finger over the vein to guide the shaft of the exposed needle. It the site is touched, repeat thedisinfection.

Question 8

What is the preferred reagent for disinfecting the site?

Answer 8

alcohol is preferable to povidone iodine
- blood contaminated with povidone iodine may falsely increase levels of potassium, phosphorus or uric acid in laboratory test results

Question 9

How do you perform the venepuncture?

Answer 9

1. Anchor the vein by holding the patient’s arm and placing a thumb BELOW the venepuncture site.
2. Ask the patient to form a fist so the veins are more prominent.
3. Enter the vein swiftly at a 30 degree angle or less, and continue to introduce the needle along the vein at the easiest angle of entry.
4. Once sufficient blood has been collected, release the tourniquet BEFORE withdrawing the needle

Question 10

Steps performed after the venepuncture procedure?

Answer 10

1. removing the tourniquet
   - as soon as blood flow is established, and always before it has been in place for two minutes or more
2. Withdraw the needle gently and apply gentle pressure to the site with a clean gauze or dry cotton-wool ball.
3. Ask the patient to hold the gauze or cotton wool in place, with the arm extended and raised.
4. Ask the patient NOT to bend the arm, because doing so causes a haematoma

Question 11

Systems for collecting multiple tubes of blood?

Answer 11

1. use evacuated tubes with a needle and tube holder.
   - This system allows the tubes to be filled directly
2. use a syringe or winged needle set instead.

Question 12

How to use a syringe/winged needle set to collect blood?

Answer 12

1. place the tube into a rack before filling the tube.
   - To prevent needle-sticks, use one hand to fill the tube or use a needle shield between the needle and the hand holding the tube.
2. Pierce the stopper on the tube with the needle directly above the tube using slow, steady pressure.
   - Do not press the syringe plunger because additional pressure increases the risk of haemolysis.
3. Where possible, keep the tubes in a rack and move the rack towards you. Inject downwards into the appropriate coloured stopper.
   - DO NOT remove the stopper because it will release the vacuum.
4. If the sample tube does not have a rubber stopper, inject extremely slowly into the tube as minimizing the pressure and velocity used to transfer the specimen reduces the risk of haemolysis.
   - DO NOT recap and remove the needle.
5. Before dispatch, invert the tubes containing additives for the required number of times (as specified by the local laboratory).

Question 13

What do you do after completeing the procedure?

Answer 13

1. Discard the used needle and syringe or blood sampling device into a puncture-resistantsharps container.
2. Check the label and forms for accuracy. The label should be clearly written with the information required by the laboratory, which is typically the patient’s first and last names, file number, date of birth, and the date and time when the blood was taken.
3. Discard used items into the appropriate category of waste. Items used forphlebotomythat would not release a drop of blood if squeezed (e.g. gloves) may be discarded in the general waste, unless local regulations state otherwise.
4. Performhand hygieneagain, as described above.
5. Recheck the labels on the tubes and the forms before dispatch.
6. Inform the patient when the procedure is over.
7. Ask the patient or donor how they are feeling. Check the insertion site to verify that it is not bleeding, then thank the patient and say something reassuring and encouraging before the person leaves.

Question 14

Name the tubes used for sample collection and what they are used for?

Answer 14

1.Blood Culture
2.Light Blue Top (plasma):3.2% sodium citrate
- These tubes are used for coagulation tests and need to be completely filled to ensure the proper ratio of blood to anticoagulant.
3.Red Top (serum):Plain and gel
- Used for chemistry and reference tests.
4.Green Top (plasma):With and without gel, contains lithium heparin
- These tubes are used primarily for chemistry tests.
5.Lavender or Pink Top (plasma):Contains EDTA
- Used primarily for hematology and blood bank testing.
6.Gray Top (plasma):Contains sodium fluoride/potassium oxalate
- Used by chemistry for glucose testing.
7.Yellow Top (plasma and cells):Contains ACD solution A or B
- Used for Genetics testing.