What is the function of a blood collection tube that contains EDTA?

The function of a blood collection tube containing EDTA (ethylenediaminetetraacetic acid) is to act as an anticoagulant to prevent blood clotting. EDTA works by binding to calcium ions in the blood, which are essential for the coagulation process. By chelating these calcium ions, EDTA effectively inhibits the normal clotting mechanisms, thereby ensuring that the blood sample remains in a liquid state. This property is crucial when analyzing blood samples for various tests, as it allows for accurate assessment of blood cells and other components without the interference of coagulation.

While some tubes may be used for transportation, preservation, or other purposes, the primary and defining role of EDTA is its ability to maintain blood in a non-clotted state.