Peripheral venous access may be needed in a variety of clinical settings to obtain one-off blood samples (venepuncture) or to provide prolonged access to the bloodstream for blood sampling or giving intravenous infusions (cannulation).
It can be more difficult to access veins in certain groups of patients such as older people, or those with darker skin. There may be multiple attempts before cannulation is successful, which can cause pain or discomfort. Delays in cannulation can cause delays in diagnosis and treatment, and multiple attempts at cannulation by different practitioners reduces hospital productivity (Crowley et al. 2011). If a peripheral vein cannot be accessed, patients may need central venous catheterisation, which poses greater risks and is more time consuming.
There is limited evidence on the percentage of patients whose veins are difficult to access. It is likely that the experience and ability of the practitioner affects the success rate of the procedure (Crowley et al. 2011).