Arterial and venous blood culture

 Q: Venous blood cultures tend to get more contaminated than arterial blood cultures?

A) True

B) False

Answer: False

We were able to find only one small study of 51 patients in the literature which is more than three decades old. So although the evidence is weak, blood cultures obtained either via veins or arteries have the same yield. Said that it does not justify obtaining the blood cultures from the freshly placed arterial lines just for the sake of ease. Blood cultures obtained via catheters have an extremely high ratio (OR=2.69) of being contaminated. This includes freshly placed catheters. If there is no contra-indication, blood cultures should always be obtained through fresh venipuncture, preferably from upper extremity blood vessels.

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#procedures

References:

1. Väisänen IT, Michelsen T, Valtonen V, Mäkeläinen A. Comparison of arterial and venous blood samples for the diagnosis of bacteremia in critically ill patients. Crit Care Med 1985; 13:664. 

2. Snyder SR, Favoretto AM, Baetz RA, et al. Effectiveness of practices to reduce blood culture contamination: a Laboratory Medicine Best Practices systematic review and meta-analysis. Clin Biochem 2012; 45:999.