Order of Draw

1Step-by-Step Procedure

1. 1

   First: blood culture bottles (yellow/SPS or culture-specific bottles) — drawn first to maintain sterility before any other additive can be introduced.

2. 2

   Second: light blue top (sodium citrate) — used for coagulation studies (PT, PTT, INR, fibrinogen).

3. 3

   Third: red, red-speckled, or gold/SST (serum, no additive or clot activator with gel) — used for chemistry, lipid, and serology panels.

4. 4

   Fourth: green top (sodium or lithium heparin) — used for stat chemistry and plasma-based tests.

5. 5

   Fifth: lavender or pink top (EDTA) — used for CBC, differential, and blood bank testing.

6. 6

   Sixth: gray top (potassium oxalate/sodium fluoride) — used for glucose and blood alcohol testing.

7. 7

   Invert each tube immediately after filling, per that tube's required number of inversions (citrate 3–4, SST 5, heparin and EDTA 8–10) — never shake.

8. 8

   If a blood culture is NOT ordered, the light blue citrate tube still goes first among the remaining tubes.

What Your Instructor/Preceptor Is Checking

• ✓

  States the six-tube sequence from memory without hesitation: blood culture → light blue → red/gold/SST → green → lavender/pink → gray.

• ✓

  Correctly explains why the sequence exists (preventing additive carryover between tubes).

• ✓

  Inverts each tube the correct number of times immediately after filling.

• ✓

  Adjusts the sequence correctly when a blood culture is not ordered (starts with light blue).

• ✓

  Never shakes a tube — uses gentle end-over-end inversion only.

Common Mistakes

• ⚠

  Drawing the red/SST tube before the light blue citrate tube, which can carry clot activator into the coagulation tube and invalidate PT/PTT results.

• ⚠

  Shaking tubes instead of gently inverting them, which can cause hemolysis.

• ⚠

  Forgetting that blood cultures always come first, even before coagulation tubes, to protect sterility.

• ⚠

  Under- or over-inverting a tube relative to its required count.

• ⚠

  Confusing lavender/pink (EDTA, for CBC) with light blue (citrate, for coagulation) under time pressure.

Practice Tips

• →

  Use a mnemonic you've practiced out loud, not just read silently — verbal recall under pressure is different from recognition.

• →

  If a requisition only orders one or two tests, you only need to draw the tubes those tests require, still in correct relative order.

• →

  This is the fact most likely to appear on the written exam in a "which tube is drawn first/last" format — know it cold, not just generally.

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