American Medical Technologist (AMT) Practice Exam

Which color-coded tube is most frequently associated with coagulation tests?

1. Red

2. Purple

3. Green

4. Light blue

The correct answer is: Light blue

The light blue tube is specifically designed for coagulation tests, making it the most frequently associated choice for these types of analyses. This tube typically contains sodium citrate as an anticoagulant, which is essential for preserving the blood’s natural clotting function during the testing process. By binding calcium ions, sodium citrate prevents clot formation in the sample, enabling accurate measurements of clotting factors. When performing coagulation tests, such as PT (prothrombin time) and aPTT (activated partial thromboplastin time), the accurate measurement of clotting activity is crucial for diagnosing bleeding disorders or for monitoring anticoagulation therapy. The light blue tube's specific formulation supports such requirements, ensuring that the blood sample remains in a state that accurately reflects the patient's coagulation profile. In contrast, other tubes serve different purposes. For example, the red tube is typically used for serum tests without anticoagulants, while the purple tube contains ethylenediaminetetraacetic acid (EDTA), which is primarily intended for hematological studies rather than coagulation. Green tubes, often used for tests requiring heparin, may not provide the same applicable results for standard coagulation assessments. This distinction reinforces the light blue tube's primary role in coagulation