Phlebotomy: Order of Draw

Phlebotomy: Order of Draw, Tubes, Additives, Tests, and Departments

The order of draw in phlebotomy is crucial to prevent cross-contamination of additives between tubes, which could lead to inaccurate test results. The standard order is as follows:

  1. Blood Culture / Sterile Specimen Tube

    • Color: Yellow (SPS - Sodium Polyanethol Sulfonate) or Blood Culture Bottles

    • Additive: SPS or Nutrient Broth

    • Common Tests: Blood cultures to detect bacteria or other microorganisms.

    • Department: Microbiology

  2. Light Blue Top Tube

    • Color: Light Blue

    • Additive: Sodium Citrate (anticoagulant)

    • Common Tests: Coagulation studies (e.g., PT/INR, PTT, Fibrinogen).

    • Department: Coagulation (Hematology)

  3. Red Top Tube (No Additive) / Serum Separator Tube (SST) / Gold/Tiger Top

    • Color: Red (No Additive), Gold, or Tiger (Red/Gray mottled)

    • Additive: No additive (Red), or clot activator and gel separator (SST/Gold/Tiger Top)

    • Common Tests: Serology, chemistry, immunology, drug levels, type & crossmatch (Red only).

    • Department: Chemistry, Immunology, Serology, Blood Bank

  4. Green Top Tube / Light Green Top Tube

    • Color: Green (Dark or Light Green)

    • Additive: Heparin (Sodium, Lithium, or Ammonium Heparin)

    • Common Tests: STAT chemistry tests, ammonia, cardiac enzymes.

    • Department: Chemistry

  5. Lavender/Purple Top Tube

    • Color: Lavender/Purple

    • Additive: EDTA (Ethylenediaminetetraacetic acid) - an anticoagulant that preserves cell morphology.

    • Common Tests: Hematology tests (e.g., CBC, Differential, Hemoglobin A1C, ESR).

    • Department: Hematology

  6. Pink Top Tube

    • Color: Pink

    • Additive: EDTA (specifically formulated for blood bank use)

    • Common Tests: Blood bank tests (e.g., Type & Screen, Crossmatch).

    • Department: Blood Bank

  7. Gray Top Tube

    • Color: Gray

    • Additive: Sodium Fluoride (glycolysis inhibitor) and Potassium Oxalate (anticoagulant)

    • Common Tests: Glucose (fasting, 2-hour post-prandial, GTT), Lactic Acid, Alcohol levels.

    • Department: Chemistry

  8. Royal Blue Top Tube

    • Color: Royal Blue

    • Additive: No additive, EDTA, or Heparin (trace element-free)

    • Common Tests: Trace elements (e.g., Copper, Zinc, Lead, Aluminum).

    • Department: Chemistry/Toxicology

Key Considerations:

  • Inversion: Tubes with additives must be gently inverted a specific number of times immediately after collection to ensure proper mixing of the additive with the blood.

  • Patient Identification: Always confirm patient identity before blood collection.

  • Site Selection: Choose an appropriate venipuncture site, typically the antecubital fossa.

  • Contamination: Following the proper order of draw prevents contamination of subsequent tubes by additives from previous tubes, which can interfere with test results.

  1. Question: Why is the "order of draw" crucial in phlebotomy?

    • A) To ensure patient comfort during venipuncture.

    • B) To prevent cross-contamination of additives between tubes, leading to inaccurate test results.

    • C) To determine the proper needle gauge for collection.

    • D) To identify the patient correctly.

  2. Question: Which tube color and additive are used for coagulation studies like PT/INR and PTT?

    • A) Red Top Tube, No additive

    • B) Lavender/Purple Top Tube, EDTA

    • C) Light Blue Top Tube, Sodium Citrate

    • D) Green Top Tube, Heparin

  3. Question: A phlebotomist needs to collect blood for a CBC and Hemoglobin A1C. Which tube color and additive should be used?

    • A) Gray Top Tube, Sodium Fluoride and Potassium Oxalate

    • B) Pink Top Tube, EDTA

    • C) Lavender/Purple Top Tube, EDTA

    • D) Royal Blue Top Tube, Heparin

  4. Question: What is the primary function of Sodium Fluoride as an additive in a Gray Top Tube?

    • A) To prevent blood from clotting.
      B) To activate clotting.

    • C) To separate serum from cells.

    • D) To inhibit glycolysis.

  5. Question: Which department processes blood cultures collected in a Yellow (SPS) tube or Blood Culture Bottles?

    • A) Hematology

    • B) Chemistry

    • C) Microbiology

    • D) Blood Bank

  6. Question: What is the consequence of not inverting tubes with additives immediately after collection?

    • A) The tube may clot prematurely.

    • B) The additive may not properly mix with the blood, leading to inaccurate test results.

    • C) The tube may break during transport.

    • D) The patient may experience more discomfort.