Why should an alcohol swab be allowed to dry before venipuncture?

Allowing the alcohol swab to dry before performing venipuncture is crucial for two main reasons: to prevent stinging and to ensure sample integrity. When an alcohol swab is applied to the skin, it disinfects the area by killing bacteria and preventing infection. If the venipuncture is performed while the alcohol is still wet, the residual alcohol can cause two issues.

Firstly, the alcohol can provoke a stinging sensation when the needle penetrates the skin. This is particularly important to consider when working with patients, as a painful experience can lead to anxiety and decreased cooperation during the procedure.

Secondly, and perhaps more crucially for the quality of the blood sample, any remaining alcohol can interfere with the assay and the proper function of certain laboratory tests. It can alter the composition of the blood sample and potentially introduce artifacts that may affect the results. For these reasons, allowing the alcohol to completely evaporate before proceeding with the venipuncture maximizes both comfort for the patient and the integrity of the blood sample collected.