Blood Cultures

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Last updated: January 20, 2021
Revisions: 12

Original Author(s): Ollie Jones
Last updated: January 20, 2021
Revisions: 12

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A blood culture is a microbiological culture of a peripheral blood sample. As blood is usually a sterile environment, culturing can show the presence of a systemic infection, such as septicaemia. If the culture is positive, the causative micro-organism can usually be identified, and antibiotic sensitivity testing performed.

The process of collecting blood for culture can be divided into four steps; explanation and consent, preparation, procedure and aftercare. We shall now look at these stages in more detail.

Explanation and Consent

  • Confirm the patients identification
    • Check full name, DOB, and hospital number
    • Confirm against patients wristband
  • Explain rationale for the procedure
    • Describe the procedure
    • State the importance of the procedure in identifying a bacteraemia
  • Explain the risks of the procedure to the patient
    • Infection (can be minimised by sterile equipment and aseptic non-touch technique)
    • Structure missed or another structure hit (nerve, artery, or bone)
    • Haematoma or phlebitis may develop
  • Ask about relevant past medical history
    • Blood clotting disorders or medication that affects blood clotting (e.g. warfarin)
    • Arterio-venous fistula present
    • Previous breast surgery or lymph node removal
  • Ask about needle phobia
  • Ask about preferred location for puncture site
    • Antecubital fossa or dorsum of the hand are the preferred locations; avoid other sites if possible (especially femoral stabs) due to high risk of contamination
    • Only take blood for culture through a peripheral cannula if it is not possible to collect from a fresh puncture site

Check that the patient is happy to go ahead with the procedure. Ask the patient if they would like a chaperone present


When in the treatment room, prepare your equipment on an appropriate equipment trolley

  • Decontaminate your hands
  • Clean your trolley and plastic tray with appropriate aseptic agent (e.g. Chlor-clean), allowing to dry fully. Decontaminate your hands
  • Gather the rest of the equipment into the plastic tray on the trolley and move to the patients bedside
    • Equipment required includes needle and collection set, tourniquet, appropriate aerobic and anaerobic blood culture bottles, chlorhexidine wipes, cotton ball with tape, inco pad, and sharps bin

Once at the patient’s bedside

  • Re-confirm the patients identification
  • Decontaminate your hands and position the patient’s arm underneath a pillow with the inco pad
  • Apply the tourniquet, select a suitable vein, remove the tourniquet and carry on with the procedure


  • Decontaminate your hands and then clean the puncture site with the chloraprep wipe (in a cross-hatch formation) and allow to air dry
  • Apply the tourniquet and do not repalpate the cleaned skin
  • Decontaminate your hands; remove the caps from the blood culture bottles, then clean the top of the bottles with a new chloraprep wipe for 15 seconds and allow to air dry
  • Don your gloves and apron
  • Placing traction on the skin below the intended puncture site, insert the needle with the bevel up at an angle of 30o into the puncture site
  • Advance the needle with the collection set and release traction on the skin
  • Attach the sample bottles in turn, filling up to the necessary level and inverting each bottle once removed. Around 10mls is needed, minimum.
    • Importantly, fill up the aerobic bottle first (due to any residual air in the needle and collection set) and then the anaerobic bottle
  • Once both culture bottles are filled, release the tourniquet
  • Place the cotton wool over the puncture site and slowly withdraw the needle
    • Place the needle straight into the sharps bin
  • Apply direct pressure over the puncture site for 1min and secure with tape
  • Discard all waste into the correction disposal bins and ensure the patient is comfortable
  • Remove your gloves and decontaminate your hands
  • Place the sample culture bottles into the sample bag alongside the blood culture request form
  • Document in the patient’s medical notes that blood cultures have been taken, using your specific trust blood culture documentation if available.

If you are unsuccessful in obtaining blood, remove needle and restart the whole procedure. Never reinsert the same needle into a patient. It is good practice to have maximum of two attempts before finding a colleague to attempt instead.

If the patient is known to be “high risk”, place bottles and request form into a biohazard bag. Both the sample and the form should also be labelled with “Danger of Infection” stickers or hospital equivalent.


Instruct the patient to inform the nursing staff if:

  • Puncture site becomes red, hot, or swollen
  • They develop pain at the puncture site

Thank the patient and leave the patient’s bedside