MedSchool: Ace Your OSCEsThe Medical Company
GET - On the App Store
IV Cannulas

Cannula Insertion



  • Explain the procedure and ask for patient's consent.
  • Wash your hands.
  • Position the patient appropriately - raise the bed, lower the bed rail, and position the limb appropriately. Consider using a pillow to elevate the limb.


  • Set up all of your equipment on a trolley, and prime the line if required.
  • Apply the tourniquet, then wash your hands and don gloves.
  • Prepare the site by decontaminating with an alcohol swab then allowing the area to air dry. 
  • Inject 1% lignocaine if appropriate - some people prefer this, though it can distort the anatomy and make a vein more difficult to find.


  • Stretch the skin distal to the insertion site, and tell the patient to prepare for a sharp ‘scratch’.
  • Insert the needle bevel up, ~30 degrees from the skin, until flashback is seen. Then flatten the needle out and advance 2mm.
  • Hold the needle still, and advance the cannula to its hilt.
  • Release the tourniquet, then remove the needle. Some cannulas will bleed as this point (if they have no stop valve) - this can be avoided by placing pressure on the skin proximal to the cannula, or anticipated by placing a piece of gauze beneath the cannula to catch any blood.
  • Attach the bung to the cannula, which will stop any bleeding. If blood collection is required, attach the 10-20mL syringe to the bung and withdraw the desired amount.
  • Flush the cannula using 10mL of 0.9% sodium chloride.
  • Dress the area by taping the cannula and applying the transparent dressing. If a patient is likely to move, an elastic or woven bandage can be used to cover an entire part of the limb.

Finishing Up

  • Dispose of sharps and other waste. Remove the gloves and wash your hands.
  • Document the cannula insertion including the date, site, the cannula gauge and the number of attempts.
Want more info like this?
  • Your electronic clinical medicine handbook
  • Guides to help pass your exams
  • Tools every medical student needs
  • Quick diagrams to have the answers, fast
  • Quizzes to test your knowledge
Sign Up Now