What is the role of EDTA in blood collection tubes?

EDTA, or ethylenediaminetetraacetic acid, is an anticoagulant that is commonly used in blood collection tubes specifically for the purpose of preventing clotting. When blood is drawn into a tube containing EDTA, this compound binds to calcium ions in the blood. Calcium is essential for the clotting process; by chelating or sequestering these ions, EDTA effectively inhibits the coagulation cascade that would normally lead to blood clot formation. This characteristic makes EDTA an essential additive for laboratory tests that require whole blood or plasma free from clots, such as complete blood counts or certain types of research studies.

Other choices, while relevant to blood collection, do not appropriately describe the function of EDTA. Promoting clotting is contrary to EDTA’s role, and enhancing glucose preservation or stabilizing bilirubin levels involves different additives and methods. For these reasons, the answer that correctly identifies EDTA's function is that it prevents clotting.