Ensure that patient and health care provider safety standards are met during this procedure including:

  • Risk assessment and appropriate PPE
  • 4 Moments of Hand Hygiene
  • Procedural Safety Pause is performed
  • Two patient identification
  • Safe patient handling practices
  • Biomedical waste disposal policies
  1. Select Patient/Apply Related Policies
  2. Obtain Equipment
  3. Prepare Equipment
  4. Prepare Environment
  5. Prepare Access Cap
  6. Connect Blood Withdrawal System
  1. Position Stopcock for Sampling
  2. Collect Discard Sample
  3. Collect Samples
  4. Flush Catheter
  5. Flush Sampling Port
  6. Label Specimens
  7. Document




Select Patient and Apply Relevant LHSC Policies

  • Verify there is an order, protcol or medical directive to support the sample.
  • Order laboratory tests in PowerChart and obtain labels.
  • Check labels with patient's armband at bedside to verify patient, test and label is correct.
  • Blood drawing from indwelling arterial or central venous lines is done through a stopcock with a needleless access device on the sampling port.

Change the ethanol Swab Cap(TM) cap after each access. Do not remove the needleless access device to draw lab samples; draw samples through this device. Needleless access caps that cannot be cleared of blood or are contaminated should be replaced.

Follow LHSC policies for hand hygiene and infection control before, during and after procedure. Perform hand hygiene and don a mask with eye shield and non-sterile gloves prior to blood sampling.

LHSC Hand Hygiene Policy

LHSC Routine Practices

LHSC Donning and Doffing Policy

Confirm 2 patient identifiers as per LHSC Policy for Patient Identification


A medical order or supportive protocol is required by the College of Nurses.

The procedure for blood drawing maintains a closed system.


Obtain Equipment

  • Perform hand hygiene.
  • Obtain non-sterile gloves and asess risk for need of a face shield.
  • LHSC Routine Practices Policy
  • LHSC Hand Hygiene Policy
  • Collect necessary equipment:
    • Vacutainer with indwelling needle for blood collection
    • Ethanol based Swab Cap(TM)
    • Blood collection tubes as required for ordered lab tests
    • Blood gas syringe if required
    • Two additional DISCARD blood collection tubes. One will be used to collect the discard sample and the other will be used to collect backflush.
    • Order labels from Powerchart


Note: If you are not collecting any blood into vacuum tubes (i.e, blood gases, glucometer samples or point-of-care testing), a syringe can be used to collect the discard sample and to back flush.


The needless system reduces the risk for stopcock contamination and needlestick injuries.

Collection of backflush solution into a disposable blood tube reduces exposure to blood products. Backflushing reduces potential to introduce pathogens.




Prepare Equipment

  1. Assemble vacuntainer, Swab Cap (TM), blood sample tubes and/or blood gas syringe





Prepare Environment

  1. Explain procedure to patient/family.
  2. Press the alarm silence button and hold for 4 seconds if samples are to be drawn from an arterial line.


Blood sampling from an arterial line reduces patient discomfort from needle sticks, however, patients should be advised that they may feel a warm sensation in their extremity during line fllushing.

When the silence button is pressed once, all alarms are suspended for 2 minutes. When the button is depressed for 4 seconds, the alarm is suspended for 5 minutes. This will prevent nuisance alarms during blood sampling from the arterial line.


Prepare Access Cap

  1. Perform hand hygiene and don non-sterile gloves, face shield if required.
  2. Remove antiseptic Swab Cap (TM)

Blood Sampling Equipment


Follow routine precautions and the 4 moments of hand hygiene outlined by LHSC and the MoHLTC.

The Centre for Disease Control (CDC) recommends 70% alcohol or an or an iodophor for cleansing injection sites. Chlorhexidine adheres to provide prolonged gm positive antimicrobial properties.

Swab Cap (TM) contains a foam pad within the cap, which is impregnated with 70% isopropyl alcohol that bathes the Microclave(TM) clear connector. This is used as part of our Central Line Associated Blood Stream Infection (CLA-BSI) reduction strategy.


Connect Blood Drawing System

Connect vactainer with indwelling needle to the Microclave(TM) clear connector on stopcock.



This provides blood access.


Position Stopcock for Sampling

Open stopcock toward patient and sampling port by turning the white prong of the 3-way stopcock toward the flush device. Turn stopcock to 90 degrees.



This position is open to the patient and the sampling port and closed to the flush device.


Collect Discard Sample (Arterial)

  1. Insert one of the DISCARD  tubes into the vaccutainer with indwelling needle.
  2. Depress the blood tube to activate the vacuum.
  3. Turn the stopcock off toward the flush system.
  4. Obtain a MINIMUM 3 ml discard if from an arterial line (including if glucometer and blood gas sampling).
  5. Dispose of discard samples into the sharps container.

Note: If you are not collecting any blood tubes, you can collect discard sample into an extra syringe.


Collect Discard Sample (Venous Samples)

  1. Assess all IVs that are running distal to the catheter and stop during sampling.
  2. All IVs that are running into any lumen of a multilumen or PICC catheter (including an introducer) must be off for blood sampling.
  3. A minimum discard sample of 5 ml is required when drawing blood samples from a central venous lines.
  4. Peripheral IVs should not be used for blood sampling due to the high risk for hemolysis.
  5. If IVs cannot be temporarily stopped, the patient should have an arterial line for lab sampling.

    Exception: Venous blood gases for the purpose of admission screening for metabolic acidosis can be done if the IVs cannot be stopped, however, the results may be inaccurate with high infusion volumes.


An adequate discard sample is even more important when a very small blood volume is withdrawn, as the potential for signficant sample dilution is greater.

LHSC Sharps Handling Policy






Central venous lines are longer catheters with increased catheter desadspace. They require a larger discard sample to ensure sampling accuracy.

Infusions from distal peripheral lines or from any other port of a multilumen PICC or temporary venous catheter can dilute or contaminate a lab sample. These IVs should be turned off prior to sampling. If an infusion cannot be safely stopped during blood sampling, an alternative method is recommended.


Collect Blood Samples

  1. Turn the white stopcock prong into a 45 degree position before releasing the vaccum or changing tubes/syringe.
  2. Remove the discard sample into the sharps container and connect the first blood sample tube or syringe.
  3. ALWAYS turn stopcock to 45 degrees before releasing the vaccum on the blood tube, before changing tubes.
  4. If your are drawing blood from a heparinized line (saline without heparin is our standard setup), draw the blue top tubes for INR/PTT last, but BEFORE blood gas sample.

Green top tube


When the stopcock is turned to 45 degrees, the stopcock is off in all directions.

If tubes or syringe changes are made when the stopcock is open to the sampling port, blood splatter may occur.

If the stopcock is turned off to the sampling port in a 90 degree position, flush solution can enter the next sample drawn and dilute the specimen or contaminate it with flush solution. 



Flush the Patient Catheter

  1. When all of the desired specimens have been collected, turn the white prong on the stopcock toward the sampling port.
  2. Pull the flush device located below the transducer to activate the fast flush mechanism.
  3. Flush until there is no visible evidence of blood.



The prong points toward the "off" position. This position is open to the patient and the flush device but closed to the sampling port.

Any blood remaining in the line may trigger clot formation.


Flush the Stopcock

  1. Connect the second extra syringe or blood tube to the sampling port.
  2. Turn the stopcock so that the white prong points toward the patient's catheter.
  3. Activate the flush device and back flush saline into the DISCARD tube or syringe.
  4. Ensure all blood is cleared from the Microclave(TM) clear connector.
  5. Replace Microclave(TM) clear connector that have residual blood.
  6. Connect a new Swab Cap (TM) on the Microclave(TM) clear connector.
  7. Remove non-sterile gloves, perform hand hygiene.




Blood provides a medium for bacterial growth.

Backflushing into a contained blood tube reduces caregiver exposure to blood.




In accordance with the MoHLTC 4 moments of hand hygiene and LHSC infection control policies in an effort to reduce risk of transmission of microorganisms and secretions.

LHSC Hand Hygiene Policy

LHSC Routine Practices Policy



Label Specimens

  1. Place labels on specimens.
  2. Verify that the label name and patient are correct.
  3. Sign sample requisition and record time sample was drawn.
  4. Send blood samples to the lab in a biohazardous bag.


Samples will be discarded by lab if unsigned.



  1. List sample collected on the nursing graphic record.
  2. Ensure an order, protocol or medical directive is present to support the sample
  3. If blood sample has been drawn according to a prn protocol or medical directive, document in the AI record the reason the sample was obtained.
  4. Review signficant findings with physician. Signficant findings include abnormal results, return to normal following treatment or normal results that may rule out issues of concern.


Medical orders are required for blood sampling. PRN protocols or medical directives require documentation to support hte decisions.

Note that a written order is required for non-protocol driven samples (e.g., cultures, cardiac or hepatic enzymes, urea and creatinine).

To communicate signficant fidngins to a physican and obtain orders for intervention if indicated.


Gillies D, O’Riordan L, Wallen M, et al. Optimal timing for intravenous administration set replacement. Cochrane Database Syst Rev 2005;(4):CD003588.

Luebke, M., et al. (1998). Am J Infection Control, 26: pp. 437-441.

Plott, R., Wagner, R., Tyring, S. (1990). Archive Dermatology, 126: pp 1441-1444.

Salzman, M., Isenberg, H., Rubin, L. (1993). Journal of Clinical. Microbiology, 31: pp. 475-479

Developed by: Brenda Morgan, CNS, CCTC 1988

Revised: June 30, 2016, Revised August 17, 2018