NHA Phlebotomy Certification Practice Exam

Lavender stopper tubes are commonly used for hematology tests because they contain ethylenediaminetetraacetic acid (EDTA), an anticoagulant that helps to preserve the integrity of the blood sample for analysis. However, these tubes are not suitable for coagulation tests, which require samples that can form a clot. Coagulation analyses typically rely on serum samples, which are collected in tubes that do not contain anticoagulants, such as those with a red or gold stopper. When testing for coagulation factors, the presence of an anticoagulant like EDTA can interfere with the clotting process and lead to inaccurate results. Recognizing this distinction is important for proper sample collection and test accuracy in a clinical setting.