Frequently Asked Questions & Testing Guidelines (CPT)

The Order of Draw is a strict sequence established by the Clinical and Laboratory Standards Institute (CLSI) for collecting blood in additive tubes during venipuncture. It begins with sterile Blood Cultures, followed by Sodium Citrate (Light Blue), Serum (Red/Gold SST), Heparin (Green), EDTA (Lavender/Pink), and Sodium Fluoride/Potassium Oxalate (Gray). Following this sequence prevents additive cross-contamination that would invalidate test results.

Leading national credentialing agencies include the National Healthcareer Association (NHA - CPT), American Medical Technologists (AMT - RPT), American Society for Clinical Pathology (ASCP - PBT), and National Center for Competency Testing (NCCT - NCPT).

The median cubital vein in the antecubital fossa is the first choice because it is typically large, well-anchored, and least painful. The cephalic vein on the outer arm is second choice, and the basilic vein on the inner arm is the final choice due to proximity to the brachial artery and median nerve.

A tourniquet must never remain on a patient's arm for longer than 60 seconds (one minute). Leaving the tourniquet on longer causes hemoconcentration and specimen hemolysis, which falsely elevates potassium, total protein, and red blood cell counts.