Purpose: Collects blood samples for specific laboratory tests.
Additive: Contains EDTA (Ethylenediaminetetraacetic acid) as an anticoagulant, which prevents blood from clotting by binding calcium.
Color Confusion Note: Red top tubes typically do not contain additives, but in some regions, EDTA tubes may have a red or lavender/purple cap—always check local lab standards.
Use Case: Common for hematology tests like CBC (Complete Blood Count).