ASCP Phlebotomy Technician Certification Practice Exam 2026 - Free Phlebotomy Practice Questions and Study Guide

The use of EDTA in specimen tubes primarily serves to prevent clotting. EDTA, or ethylenediaminetetraacetic acid, is an anticoagulant that binds to calcium ions in the blood. Calcium is essential for the coagulation process, as it is a vital component in the series of reactions that lead to clot formation. By chelating calcium, EDTA stops the clotting cascade, allowing for the collection of whole blood or plasma without the formation of a clot. This property makes EDTA particularly valuable in hematology tests, where a clear sample without interference from clots is necessary for accurate analysis.

Options indicating facilitation of clotting or enhancing color detection do not pertain to the role of EDTA, as its primary function is to inhibit coagulation. Similarly, while temperature stabilization might be important in specimen handling, it is not a function served by EDTA. Thus, recognizing the anticoagulant role of EDTA is essential in understanding its application in laboratory settings.