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Order of Draw & Tube Additives Flashcards

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  1. What is the correct CLSI-recommended order of draw when collecting multiple tubes via venipuncture?

    Answer: Blood cultures → Citrate → Serum/SST → Heparin → EDTA → Fluoride

    The CLSI-recommended order is blood cultures first, then citrate, serum/SST, heparin, EDTA, and finally fluoride/oxalate tubes to prevent additive carryover between tubes.

  2. Why must blood culture bottles be collected before all other tubes in the order of draw?

    Answer: To prevent contamination from tube additives and maintain sterility

    Blood culture bottles are collected first to ensure no tube additive carryover contaminates the sterile culture medium, which could cause false-positive or false-negative microbiology results.

  3. Why is the light blue (sodium citrate) tube collected before serum tubes in the standard order of draw?

    Answer: Clot activator from serum tubes could carry over and falsely affect coagulation results

    If serum/SST tubes were collected first, silica clot activator particles could carry over into the citrate tube on the needle and artificially activate coagulation, falsifying PT/INR results.

  4. When using a butterfly/winged infusion set, what must be done before collecting a sodium citrate tube?

    Answer: Draw a discard tube to eliminate air from the tubing

    The dead space air in the butterfly tubing must be displaced with blood using a discard tube; otherwise, underfilling disrupts the critical 9:1 blood-to-sodium-citrate ratio needed for coagulation accuracy.

  5. In the order of draw, EDTA (lavender) tubes are collected immediately before which tube type?

    Answer: Fluoride/oxalate (gray) tubes

    EDTA tubes are collected before fluoride/oxalate (gray) tubes, as gray tops are always the last tube in the standard CLSI order of draw sequence.

  6. What is the primary reason for following a specific order of draw during multi-tube collection?

    Answer: To prevent additive carryover that could produce erroneous test results

    Following the correct order of draw prevents cross-contamination of tube additives, which can cause significant errors such as artificially low calcium when EDTA carries over into chemistry tubes.

  7. A phlebotomist needs to collect a CBC, a BMP, and a PT/INR. What is the correct tube drawing order?

    Answer: Light Blue (Citrate), Gold (SST), Lavender (EDTA)

    The correct order is light blue (citrate) for PT/INR, then gold SST for BMP, then lavender EDTA for CBC, following the standard CLSI order of draw.