Venepuncture

Written by Bethany Taylor

Introduction

Introduce yourself with your name and role, and confirm the patient’s name and date of birth. Explain the procedure, check the patient’s understanding and obtain consent. Wash your hands.

Ensure the patient is comfortable and check which arm they would prefer blood to be taken from. Ask the patient to expose their arm by rolling their sleeve up, if necessary.

Ask the patient if they have any allergies, specifically to latex. Also ask whether they are taking any medications, specifically anticoagulants, and if they have had any surgery recently that may affect the arm you take blood from. Check whether the patient is currently in any pain.

When describing venepuncture to a patient, it is often useful to ask if the patient has had the procedure before to find out how much they know. Use simple phrases such as: “this will involve me placing a needle into your arm. You will feel a sharp scratch as I insert the needle but otherwise there won’t be any pain.”

Equipment

Collect a plastic tray, and clean both the inside and outside of the box thoroughly with an alcohol surface disinfectant wipe. You will then need to collect:

Check the expiry dates of the needle, blood tubes and alcohol swab. Ensure a sharps bin is nearby.

Equipment for venepuncture.

Equipment for venepuncture using a blue (23G) needle.


Light blue: Used for haematological tests to assess clotting, including coagulation studies (e.g. activated partial thromboplastin time (aPTT), prothrombin time (PT) and international normalised ratio (INR), D-dimer and fibrinogen. Contains sodium citrate, a reversible anticoagulant.

Gold: Used for a wide range of tests - for example in biochemistry (including urea and electrolytes, C-reactive protein, liver function tests, cardiac enzymes, lipid profile, amylase, bone profile), endocrinology (including thyroid function tests, beta-hCG), toxicology (ethanol and drug levels) and tumour markers. Contains silica, a clot activator, and a serum separator gel to separate the plasma and blood cells.

Lavender: Used for a variety of routine haematological tests, including full blood count, erythrocyte sedimentation rate (ESR), blood film and HbA1c. Contains EDTA, an anticoagulant.

Pink: Used for group and save (if there is a possibility a patient may require a transfusion) and for cross-matching (to confirm blood donor compatibility prior to transfusion). Contains EDTA, an anticoagulant.

Grey: Used for measuring glucose and lactate levels. Contains sodium fluoride (prevents glucose breakdown after taking the sample) and potassium oxalate, an anticoagulant.

Other less commonly used blood collection tubes include: red (used rarely for biochemistry tests that cannot be stored in the yellow bottle, including certain hormone, toxicology and bacterial/viral serology), green (used to measure renin and aldosterone, neutrophil function tests and cytogenetics) and dark blue (used to measure trace metals such as zinc and aluminium).

Vein selection

Wash or gel your hands. Place a pillow beneath the patient’s outstretched arm for support and ensure that the patient is comfortable.

Visual inspection

Inspect the patient’s arms for any cannulas, arteriovenous fistulae and areas of bruising, swelling, infection or broken skin. These areas are a contraindication to venepuncture and should be avoided. Avoid taking blood from an arm that has been affected by surgery, looking for signs of oedema and scarring, or pre-existing medical conditions, such as a stroke affecting movement of an arm.

Palpation

Apply the tourniquet to the patient’s arm around 4 fingers width above the planned venepuncture site. Palpate a suitable vein, which should feel soft and ‘bouncy’. Avoid veins that feel hard; this may be due to phlebitis. The median cubital vein in the cubital fossa is typically used for venepuncture.

Right anterior cubital fossa highlighting the location of the medial cubital vein.

Medial cubital vein in the right cubital fossa.


Be careful not to leave the tourniquet on for more than a minute - this can lead to blood pooling and can affect test results. To prevent this from occurring, release the tourniquet after vein selection to clean the site, and reapply it just before needle insertion.

Site preparation

Release the tourniquet, clean the area around the selected vein with circular motions moving from the centre outwards, then allow to dry completely for 30 seconds. It is essential that you do not re-palpate the area from this point onwards.

Needle insertion

Assemble the blood collection system by attaching the collection barrel to the needle.

Re-apply the tourniquet and put a pair of gloves on. Anchor the vein in place by gently pulling on the skin distal to the vein with the thumb of your non-dominant hand. Pick up the needle and with the bevel facing upwards, remove the cap and insert it into the selected vein at an angle of 15-30 degrees to the skin. Just before inserting the needle, warn the patient that there will be a ‘sharp scratch’.

Observe for flashback which confirms that the needle has entered the vein. Carefully lower the needle so it is flat against the skin, and hold it in place whilst you attach the blood collection tube(s) to the barrel.

If you see flashback but blood does not flow into the collection tube when attached, it is likely that the needle has passed through the vein. If this is the case, withdrawing the needle slightly should help.

If you are using a winged butterfly needle, you can lower the wings to anchor the butterfly to the skin. In this way you minimise movement of the needle and the chance of displacing it.

Blood collection

Attach each tube in turn according to the order of draw and allow them to fill. Remove bottles from the barrel by gently twisting and applying traction, to prevent the needle from leaving the vein. Gently invert each of the blood tubes between 3-10 times, depending on the colour of the tube.

Once all the tubes are filled, release the tourniquet and then remove the needle from the vein. Apply gentle pressure over the venepuncture site for around 2 minutes with a piece of gauze or cotton wool, to prevent haematoma formation. Ask the patient to do this, if they are able to.

Dispose of the needle and barrel in a sharps bin, and dispose of non-sharp waste in the appropriate waste bin.

Inspect the venepuncture site to check that the bleeding has stopped and apply a dressing using a clean piece of cotton wool or gauze and a sterile tape strip or plaster to secure it in place.

If multiple different coloured tubes need to be filled, you must follow the order of draw to prevent cross-contamination of tube additives affecting results. This can vary according to hospital trust, but in general:

(1) Blood cultures*, (2) Light blue, (3) Red, (4) Gold:, (5) Green, (6) Purple, (7) Pink, (8) dark blue, (9) Grey

If you are using a winged butterly needle and are starting with the light blue tube, you may wish to bring a second bottle, as it is unlikely that the first will fill completely as due to trapped air. If the tube is underfilled the sample cannot be processed. The amount of sodium citrate in the tube is measured for a certain volume of blood

*Blood cultures will soon be covered in its own page.



Following blood collection, tubes need inverting to mix the blood with the additive. This should be done gently to prevent haemolysis of the sample:

Completion

Check the patient feels comfortable and advise them to keep the dressing on for at least 30 minutes. Advise against heavy lifting or excessive strain in the arm, and to seek medical assistance if the venepuncture site becomes painful, red or swollen. Thank the patient.

Remove your gloves and wash your hands. Fill in the patient’s details on each of the blood bottles and complete the laboratory form. Seal the blood bottles and laboratory forms in the clear specimen bag, ready for collection.

Interactive markscheme


When assessing each other, click on each list item as you go along. Doing so will turn the list item green. Make careful note of any steps missed at the end.
We recommend completing any examination or procedure in under 10 minutes, but you can adjust the timer to suit your needs.
:

  1. Introduction: “Hello, I’m SimpleOSCE and I am a medical student. Today I’ve been asked to take some blood from you. Can I confirm your name and DOB? Thank you.”
  2. Explain procedure and obtain consent: “This will involve me placing a needle into your arm. You will feel a sharp scratch as I insert the needle but otherwise there shouldn’t be any pain. Would that be alright?”
  3. Enquire about allergies (latex), medication (anticoagulants) and whether the patient has had any surgery recently.
  4. Assemble the correct equipment in a cleaned tray, with the correct tubes required.
  5. Check the expiry dates of the needle, blood tubes and alcohol swab.
  6. Wash hands.
  7. Put on non-sterile gloves.
  8. Ask the patient for limb preference and apply tourniquet.
  9. Select a suitable vein.
  10. Clean the area with an alcohol swab and wait for 30 seconds.
  11. Prepare needle and blood tubes, and warn the patient about a sharp scratch.
  12. Insert the needle at a 15-30 degree angle.
  13. Fill the blood tubes in the correct order of draw.
  14. Release tourniquet and then withdraw the needle.
  15. Apply clean cotton wool or gauze and secure with tape.
  16. Dispose of the needle appropriately in the sharps waste, and dispose of other waste appropriately Instruct the patient on aftercare and thank the patient.
  17. Instruct the patient on aftercare and thank the patient.
  18. Label the blood tubes and fill in the laboratory forms correctly.
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