To minimize the possibility of contaminating a venous blood sample with an intravenous (IV) solution or infused blood product, phlebotomists are trained to select the opposite arm or an alternate site if both arms are receiving IV therapies. Blood samples diluted with IV fluids can yield erroneous laboratory results, and depending on the degree of dilution, may not be immediately identified as being contaminated. Potassium is one analyte that could be affected by contamination with IV fluid, as IV solutions may contain potassium.
When the only option is to collect blood from an arm that is being infused with IV fluid, the collection should be from a site that is below (distal to) the IV site.
