Blood samples must be drawn by phlebotomists in a specific order. This is important to avoid cross-contamination of the sample by additives found in different collection tubes. Cross contamination can occur when blood in an additive tube comes in contact with a needle and when blood is transferred from a syringe into tubes.
Filling tubes in wrong order will cause interference in specimen testing from cross contamination, tissue thromboplastin and microorganisms.
And improperly collected or contaminated specimen can give spurious results (incorrect results). Results may not be reported if it is clear that the result is invalid.
This order of draw applies for all specimens collected by syringe, tube holder, or into pre evacuated tubes.
Let the vacuum in the tube fill the blood up to its level.
Do not press the syringe plunger as this will lead to hemolysis.
Gently invert according to the instruction and be sure that the entire inner surface of the blood collection tube is coated with blood while mixing.
1️⃣: Assemble equipment.
A supply of laboratory samples tubes, which should be stored dry and upright in a rack. Check the expiry date of the tubes;
Well-fitting, non-sterile gloves;
An assortment of blood-sampling devices (needles, syringes) of different sizes;
A tourniquet;
An alcohol hand rub;
70% alcohol swabs for skin disinfection;
Gauze or cotton-wool ball to be applied over puncture site;
Laboratory specimen labels;
Laboratory requisition forms;
A puncture-resistance sharps bin.
2️⃣: Identify and prepare the patient.
Introduce yourself to the patient, and ask the patient to state their full name.
Check that the laboratory requisition form matches the patient’s identity to ensure accurate identification. (Double confirmed using IC against requisition form)
Ask whether the patient has allergies, phobias or has ever fainted during previous blood takings.
If the patient is anxious and afraid, reassure the patient.
Make the patient comfortable in a relaxed position.
Discuss the procedure to be performed and obtain verbal consent. The patient has a right to refuse the procedure at any time before the blood sampling.
3️⃣: Select the site.
Extend the patient’s arm and inspect the antecubital fossa or forearm.
Locate a vein of a good size that is visible, straight, and clear.
The median cubital vein lies between the muscles and is usually the easiest to puncture.
The vein should be visible without applying a tourniquet.
Locating the vein will help in determining the correct size of the needle.
Apply the tourniquet about 4 - 5 finger widths above the venepuncture site and re-examine the vein.
4️⃣: Perform hand hygiene and put on gloves.
Perform hand hygiene and afterward, put on well-fitting non-sterile gloves.
5️⃣: Disinfect the entry site.
Clean the site with a 70% alcohol swab adequately and allow to dry completely (about 20 - 30 seconds).
Apply firm but gentle pressure.
Start from the center of the venepuncture site and work outward to cover an area of 2cm or more.
Allow the area to dry.
Failure to allow enough contact time increases the risk of contamination.
DO NOT touch the cleaned site; in particular, DO NOT place a finger over the vein to guide the shaft of the exposed needle.
If the site is touched, repeat the disinfection.
6️⃣: Take blood.
Anchor the vein by holding the patient’s arm and placing thumb BELOW the venepuncture site.
Enter the vein swiftly at a 30 degree angle and continue to introduce the needle along the vein until the blood flow is established.
Once the blood flow is established, maintain the position of the needle, release the tourniquet and pull the plunger of the syringe lightly.
Let the blood flow into the syringe until sufficient volume of blood has been collected.
Withdraw the needle gently and apply gentle pressure to the site with a clean gauze or dry cotton-wool ball.
7️⃣: Fill the laboratory sample tubes.
Follow the correct Order of Draw for blood collection tubes to avoid cross-contamination of additives between tubes.
Place the tube into a rack before filling the tube.
Pierce the rubber stopper on the tube with the needle directly above the tube using slow and steady pressure to fill the tube.
DO NOT recap and remove the needle.
DO NOT remove the stopper because it will release the vacuum.
Gently invert the tubes according to the required number of times.
Avoid vigorous mixing to avoid hemolysis.
8️⃣: Clean contaminated surfaces and complete the procedure.
Discard the used needle and syringe into a sharp yellow bin.
Check the label and forms for accuracy.
Discard used items into the appropriate category of waste (yellow bin or general waste).
Perform hand hygiene again.
Recheck the labels on the tubes and the forms before dispatch.
Inform the patient when the procedure is over.
Ask the patient about their condition.
Check the puncture site to verify that it is not bleeding and thank the patient before leaving.