To avoid cross-contamination of additives between tubes, blood must be drawn in a specific order. This is commonly known as ‘Order of the Draw’.
It may sound like a scene from a western but the ‘Order of the Draw’ is the order in which blood samples are taken during venepuncture. This helps to reduce the contamination of additives between tubes and significantly reduces haemolysing rates of samples (CDC).
The World Health Organisation (WHO) approves and publishes the order of draw and venepuncture guidelines based on the most recent evidence.
The Order of the Draw
Individual tube colours may differ between clinical areas and brands but the additives will always remain the same. You should contact you microbiology or clinical chemistry department for further advise.
Blood Cultures and Venous Blood Gases (VBGs) should always be obtained before any other blood samples ().
After drawing each bottle must be gently inverted several times to mix the anti-coagulants etc. thoroughly. Do not shake the tubes as this will damage the blood cells and invalidate test results.