Which color stopper indicates no anticoagulant and is often used for serum tests?

Which color stopper indicates no anticoagulant and is often used for serum tests?

• A. Red
• B. Blue
• C. Green
• D. Yellow

Answer: (A)

For serum tests you need the blood to clot, so no anticoagulant should be present in the collection tube. A red stopper indicates no anticoagulant (in many plastic tubes it may also include a clot activator to speed clotting), allowing the blood to form a clot and then producing serum after centrifugation. Serum is used for many chemistry and serology tests, so the red-top tube is the go-to choice in these cases. In contrast, blue tops contain an anticoagulant (sodium citrate) for coagulation studies, green tops have heparin for plasma tests, and yellow tops are used for specific tests like blood cultures or certain specialized analyses.

For serum tests you need the blood to clot, so no anticoagulant should be present in the collection tube. A red stopper indicates no anticoagulant (in many plastic tubes it may also include a clot activator to speed clotting), allowing the blood to form a clot and then producing serum after centrifugation. Serum is used for many chemistry and serology tests, so the red-top tube is the go-to choice in these cases. In contrast, blue tops contain an anticoagulant (sodium citrate) for coagulation studies, green tops have heparin for plasma tests, and yellow tops are used for specific tests like blood cultures or certain specialized analyses.