Cannulation (IV)

Intravenous Cannulation (IV) – OSCE Guide

Intravenous cannulation (IV) is a relatively common OSCE station. You’ll be expected to demonstrate your clinical skills and ability to communicate effectively. This cannulation OSCE guide provides a clear step by step approach to cannulation, with an included video demonstration.

Check out the cannulation OSCE mark scheme here.


Wash hands (use alcohol gel or soap and water if your hands are visibly soiled)

Introduce yourself

Confirm patient details – name / DOB

Check for any allergies


Explain procedure:

I need to insert a small plastic tube into your vein using a needle

This will allow us to give you fluids and medications intravenously

It will be a little uncomfortable, but it hopefully won’t be painful


Check understanding and gain consent:

“Does everything I’ve said make sense?”

“Do you have any questions?”  

“Are you ok for me to go ahead with the procedure?”

Gather equipment

Collect all equipment needed for the procedure and place it within safe and easy reach on a tray or trolley, ensuring that all the items are clearly visible.

  • Clean procedure tray
  • Non-sterile gloves
  • Disposable apron (optional)
  • Tourniquet
  • Cannula size appropriate to the indication for cannulation
  • Sterile dressing pack – to provide a sterile field 
  • Cannula dressing
  • Luer lock cannula cap or extension set
  • Gauze swabs
  • Normal saline (0.9%) 10ml
  • Syringe10ml
  • Alcohol swab (2% chlorhexidine gluconate in 70% isopropyl)
  • Sharps container
  • Gather equipment


Preparation of equipment and the cannulation site

1. Don gloves (prior to drawing up your saline flush)

2. Open the dressing pack and place the cannula, cannula dressing and other items onto the field

3. Prepare the normal saline flush by drawing up into your syringe (if you have a pre-filled flush you can ignore this step)

4. If you are planning on using an extension set you should attach this to the flush and prime the line

5. Place a pillow under the arm to be cannulated if you feel it will make the procedure more comfortable for the patient and yourself

6. Place a field below the patient’s arm to prevent blood from spilling onto the patient or surrounding furniture

  • Don gloves (prior to setting up saline flush)

Identification of a suitable vein

1. Position the patient’s arm in a comfortable extended position that provides adequate exposure of the planned area for cannulation


2. Inspect the arm for suitable vein (it should ideally be visible without applying the tourniquet)

  • If you are planning to use the cannula for IV fluids or antibiotics you should select a site that is least restrictive for the patient (preferably distally on the arms)
  • You should also ask the patient if they have a preference as to which arm should be cannulated


3. Apply the tourniquet  approximately 4-5 finger widths above the planned puncture site


4. Palpate the vein:

  • Go for a vein that feels “springy”
  • It should ideally be straight to best accommodate the cannula
  • Tapping a vein and asking the patient to repeatedly clench their fist can make the vein easier to visualise and feel
  • It is preferable to use the patient’s non-dominant arm and to avoid areas near the elbow and wrist joints (to reduce the likelihood of dislodgement as a result of the patient’s movement)


Things to avoid when cannulating:

  • You should avoid areas where two veins are joining as valves are often present
  • Pre-existing medical conditions may prevent particular limbs from being used (e.g. arterio-venous fistula, lymphoedema, previous mastectomy)
  • Avoid areas of broken, bruised or infected skin (cellulitis)


5. Once you have identified a suitable vein clean the site with an alcohol swab for 30 seconds and then allow to dry completely over 30 seconds:

  • You should start cleaning from the centre of the cannulation site and work outwards to cover an area of 5cm or more
  • DO NOT touch the cleaned site afterwards at any point, otherwise the cleaning procedure will need to be repeated prior to cannulation
  • Inspect for a suitable vein

Inserting the cannula

1. Wash hands again

2. Don non-sterile gloves (as the procedure will be performed using aseptic non touch technique)

3. Remove the cannula sheath

4. Prepare the cannula:

  • Open the cannula wings
  • Slightly withdraw and replace the needle – this will make it glide easier when cannulating
  • Unscrew the cap at the back of the cannula and place upright in the tray (if the cannula is ported)

5. Secure the vein with your non-dominant hand from below by gently pulling on the skin distal to the insertion site

6. Warn the patient of a sharp scratch

7. Insert the cannula directly above the vein, through the skin ( at an angle of 10-30º with the bevel facing upwards)

8. Observe for flashback in the cannula chamber

9. Decrease the angle between the needle and the skin, then advance the needle a further 2mm after flashback to ensure it’s within the vein’s lumen

10. Partially withdraw the introducer needle (ensuring the needle end is within the plastic tubing of the cannula)

11. Carefully advance the cannula into the vein fully

12. Release the tourniquet

13. Place some sterile gauze directly underneath the cannula hub

14. Apply pressure to the proximal vein close to the tip of the cannula to reduce bleeding

15. Gently pull the introducer needle backwards whilst holding the cannula in position until it is completely removed

16. Connect a luer lock cap or primed extension set to the cannula hub

17. Dispose of the introducer needle immediately into a sharps container

18. Apply adhesive strips to secure the cannula wings to the skin (do not obscure the insertion site with these, as this needs to remain clearly visible to allow early detection of phlebitis)

There is significant variability in the recommended method of cannulation, therefore you should always consult your local medical school or hospital guidelines.

  • Wash hands again

Flushing the cannula

1. Inject the saline into the cannula using the flush you prepared earlier:

  • It should go in smoothly with little resistance
  • Watch for signs of swelling around the site (stop immediately if you see this)
  • If the patient complains of pain you should also stop immediately


2. Close the cannula port (if ported)

3. Secure the cannula with a dressing if the cannula is functioning appropriately

  • Inject the normal saline flush slowly, observing for evidence of extravasation

To complete the procedure…

Dispose of the clinical waste into an appropriate bin

Wash hands

Thank patient


Document details of the procedure on a visual infusion phlebitis (VIP) chart: 

  • Patient details (name / DOB / hospital number)
  • Date and time of cannulation
  • Reason for cannulation
  • Type of cannula used – (e.g. 20 gauge)
  • Site of the cannula (e.g. dorsum of the left hand)
  • Date the cannula should be removed or replaced
  • Your name, grade and contact details


Graham Bone

Senior Clinical Lecturer in Medical Education


1. WHO Guidelines on Hand Hygiene in Healthcare: a Summary. Published 2009. [LINK]

2. WHO guidelines on drawing blood: best practices in phlebotomy. Published 2010. [LINK]

3. Health service executive. National Clinical Policy and Procedural Guideline for Nurses and Midwives undertaking Peripheral Cannulation in Adults. Published 2010. [LINK]


Print Friendly, PDF & Email