From the diagram above, the most common places for cannulation and blood taking include the dorsal aspect of the hand and the cephalic vein in the forearm whereby success rates, pain level and complication rates are similar for both sites.
If having to use the cephalic vein, it is important to avoid the area of the anatomical snuffbox due to the increased risk of inadvertent puncture or cannulation of the distal radial artery.
If available, it is always best to target the larger looking veins that are easy to palpate and where the cannula will not impair the movement of the wrist or elbows.
Sites to avoid when performing cannulation include:
Veins and Veins to be Avoided
Good Veins | Veins to Avoid |
Bouncy | Hard |
Soft | Thin/Fragile |
Straight | Inflamed |
Visible | Bruised |
Well supported | Near to bony Prominences (painful) |
Has a large lumen | Areas/sites of infection |
Refills when depressed | Has undergone multiple previous punctures |