The collection area is most commonly cleansed with a 70% alcohol-based solution which serves to reduce the introduction of skin contaminants into the bloodstream and into the blood sample being collected. For certain laboratory tests, including blood cultures, the use of an iodine-based solution is used to further prevent microorganisms from contaminating the blood sample.
While preparation solutions are generally considered inert and will not affect the measurands, isopropanol or ethanol-based prep pads should not be used when samples are obtained for legal blood alcohol testing. A non-alcohol antiseptic, such as povidone-iodine, is acceptable. (Tincture of iodine should not be used because it contains alcohol.) Similarly, if the patient is being tested for halides, such as iodine, the site should not be prepared with an iodine-containing solution.
After cleansing the collection site with an alcohol-based solution, always allow the area to air dry as residual alcohol on the skin may be introduced into collection tubes and increase the risk of cellular hemolysis. Additionally, alcohol residue that has not dried on the patient skin before the needle has been inserted can sting and cause pain for the patient.
