To draw blood for a test that uses plasma, you should make sure the syringe contains an anticoagulant.

• A. True
• B. False
• C. It depends on the test
• D. Never necessary

Answer: (A)

To obtain plasma for a test, you need to prevent the blood from clotting after collection. Plasma is the liquid part of blood that remains when clot formation is stopped, and it contains all the clotting factors. If no anticoagulant is used, the blood will clot and, after centrifugation, you’ll have serum instead of plasma. For tests that require plasma, an anticoagulant must be present in the syringe or collection tube to keep the blood from clotting long enough to separate the plasma.

Different anticoagulants work in various ways (for example, some bind calcium or inhibit certain clotting factors), and the choice depends on the test’s requirements because some assays can be affected by the anticoagulant. So, when the test uses plasma, ensure the syringe contains an appropriate anticoagulant before drawing.