Registered Nurses' Association of Ontario

Blood Withdrawal

Method of Blood Withdrawal


Potential Complication


  • Removes potential

contaminate from the

catheter (CVAD)


  • Remove a specific amount of blood from catheter (CVAD) via syringe or vacutainer
  • Use a “new” syringe or vacutainer for the blood sample
  • Flush CVAD with 0.9% saline
  • Potential nosocomical blood loss
  • Potential to confuse a discard syringe with blood sample syringe

Push – Pull

  • Requires mixing the blood back and forth in a syringe several times to eliminate contaminates from the catheter (CVAD)


  • Using a 10 ml syringe, flush catheter (CVAD) with 5 ml 0.9% saline
  • Without removing syringe, 6 ml of blood is aspirated, then pushed back into catheter (CVAD)
  • Repeat this process x3
  • Remove the empty syringe and attach new syringe/vacutainer to obtain blood sample
  • Flush CVAD with 0.9% saline
  • May be difficult to obtain enough blood for 3 – 4 push-pull sequences
  • Risk of haemolysis with the agitation of blood


  • Involves returning the discard specimen after obtaining blood samples
  • Aspirate 6 ml of blood into a syringe and cap with a sterile cap
  • Obtain blood specimen(s) via a syringe or vacutainer
  • Re-infuse the discard from the 1st syringe.
  • Potential to re-infuse clot(s)
  • Potential to re-infuse contaminated discard
  • Potential for error including the possibility of confusing the discard syringe with the blood sample
Clinical Management
Care and Maintenance to Reduce Vascular Access Complications
Point of Care Resources