Drawing blood from peripheral intravenous cannula compared with venepuncture: A systematic review and meta-analysis

To synthesize the evidence evaluating if blood samples are similar when obtained from peripheral intravenous cannula compared with venepuncture.

A systematic review and meta-analysis was undertaken.

Searches were conducted in databases for English language studies between January 2000-December 2018.

The search adhered to the Meta-analysis of Observational Studies in Epidemiology guidelines. The methodological quality of studies was assessed using Joanna Briggs critical appraisal instruments. The overall quality of the evidence was assessed using the GRADE.

Sixteen studies were identified. Findings suggest haemolysis rates are higher in blood sampled from peripheral intravenous cannula. However, haemolysis rates may be lower if a peripheral intravenous cannula blood sampling protocol is followed. For equivalence of blood test results, even though some results were outside the laboratory, allowable error and were outside the Bland-Altman Level of Agreement, none of these values would have required clinical intervention. With regard to the contamination rates of blood cultures, the results were equivocal.

Further research is required to inform the evidence for best practice recommendations, including, if a protocol for drawing blood from a peripheral cannula is of benefit for specific patient populations and in other settings.

Venepuncture can provoke pain, anxiety and cause trauma to patients. Guidelines recommend blood samples from peripheral intravenous cannula be taken only on insertion. Anecdotal evidence suggests drawing blood from existing cannulas may be a common practice. Further research is required to resolve this issue.