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Phlebotomy Technician Order of Draw and Additives Flashcards

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  1. What additive is found in yellow-topped blood culture tubes?

    Answer: Sodium polyanethol sulfonate (SPS)

    Yellow-topped blood culture tubes contain SPS, an anticoagulant that also inhibits complement, phagocytes, and certain antibiotics, creating an optimal environment for bacterial growth.

  2. Why must light blue-topped coagulation tubes be filled to the exact fill line?

    Answer: To maintain the correct 9:1 blood-to-anticoagulant ratio

    Light blue coagulation tubes require a precise 9:1 ratio of blood to sodium citrate. Underfilling or overfilling alters this ratio and produces inaccurate coagulation results.

  3. Which tube additive works by activating clot formation rather than preventing it?

    Answer: Clot activator (silica particles)

    Clot activators such as silica or glass particles are coated on the inner walls of red/gold-topped tubes to promote and accelerate clot formation for serum testing.

  4. In the order of draw, why are EDTA (lavender) tubes drawn after heparin (green) tubes?

    Answer: EDTA contamination would falsely affect electrolyte and enzyme results in heparin tubes

    EDTA is drawn after heparin because EDTA contamination of chemistry tubes would falsely elevate potassium and chelate calcium, affecting multiple test results.

  5. What type of gel is found in gold-topped SST (serum separator) tubes and what is its function?

    Answer: Thixotropic gel; it forms a barrier between serum and clot during centrifugation

    SST tubes contain thixotropic gel that has a density between serum and clotted blood. During centrifugation, the gel migrates to form a stable barrier between the two layers.

  6. A phlebotomist accidentally draws a green-topped tube before a light blue-topped tube. What should be done?

    Answer: Discard the light blue tube and redraw it using a new venipuncture

    If the order of draw is not followed and a coagulation tube may be contaminated with heparin carry-over, the light blue tube must be discarded and a new one drawn from a fresh venipuncture.

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