Free Tool — Phlebotomy
Phlebotomy Order of Draw
Interactive blood draw tube sequence per CLSI GP41. Click any tube for additive, purpose, common tests ordered, and required mix inversions.
Order of Draw
Phlebotomy tube sequence per CLSI GP41
Remember the mnemonic:
Somebody Bringing Sally Roses Gets Lots PrettyGradually
(Yellow, Blue, Red, Roses/Gold, Green, Lavender, Pink, Gray)
CLSI GP41: Clinical and Laboratory Standards Institute guidelines for blood collection and handling
Pro Insights
- Pediatric micro-collection tube order and minimum volumes:See in app
- Hemolysis prevention techniques by tube type and draw method:See in app
- CLSI GP41 exceptions: when to discard the first tube:See in app
Phlebotomy Prep
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1,000+ practice questions for the CPT phlebotomy exam + order of draw reference — works offline
Why Order of Draw Matters
The order of blood collection tube draw is not arbitrary — it prevents additive carryover contamination between tubes. If EDTA from a lavender tube carries over into a coagulation tube (light blue), it chelates calcium and falsely prolongs PT and aPTT results. If clot activator from a gold SST tube carries over into a heparin tube (green), it can cause false clotting. The CLSI (Clinical and Laboratory Standards Institute) standard GP41 establishes the order of draw to minimize these cross-contamination errors.
The standard order per CLSI GP41 is: blood cultures (yellow) → coagulation (light blue) → serum tubes (red, gold) → heparin plasma (green) → EDTA (lavender, pink) → glucose/alcohol preservation (gray). When only one or two tubes are needed, you still follow this relative order — if drawing a light blue and a lavender, the light blue goes first. The light blue (sodium citrate) tube must always precede EDTA tubes to prevent citrate-to-EDTA contamination that would alter coagulation results.
The order of draw is heavily tested on phlebotomy certification exams (NHA CPT, ASCP PBT, AMT RPT) and appears on NREMT exams at the AEMT and Paramedic level. Common exam scenarios: which tube is drawn first when doing a PT/INR and CBC together (light blue before lavender), what happens if blood cultures are drawn after a gold tube (contamination risk — cultures must be first), and why the light blue tube must be filled to exact volume (underfilling dilutes the citrate ratio and falsely prolongs coagulation results).
Frequently Asked Questions
What is the order of draw for a routine blood draw?
Per CLSI GP41: 1) Blood cultures (yellow SPS), 2) Coagulation (light blue - sodium citrate), 3) Serum tubes (red no additive, then gold SST), 4) Heparin plasma (green), 5) EDTA (lavender, then pink), 6) Glucose preservation (gray). If blood cultures are not ordered, start with light blue. If coagulation tests are not ordered, start with the appropriate serum or EDTA tube.
Why must the light blue tube be filled to the line exactly?
The light blue tube contains a 3.2% sodium citrate solution in a precise ratio to blood — typically 1 part citrate to 9 parts blood. If the tube is underfilled, the citrate-to-blood ratio increases, over-anticoagulating the sample and producing a falsely prolonged PT/INR and aPTT. Short-draw light blue tubes must be rejected and redrawn. This is the most commonly missed detail in coagulation specimen collection.
Can I draw a lavender tube before a light blue tube?
No — EDTA (lavender) must always come after the light blue coagulation tube. EDTA chelates calcium ions. If even a tiny amount of EDTA carries over into the coagulation tube via the needle, it will chelate the calcium in that sample and produce dramatically falsely prolonged coagulation results. This is one of the most clinically significant order-of-draw errors.
What happens if blood cultures are drawn last?
Blood cultures should always be drawn first (or second if a light blue coagulation tube is needed from the same venipuncture). Drawing blood cultures last risks contaminating the culture with bacteria from the skin that accumulated in the needle from the previous draws, or with additives from other tubes. False-positive blood cultures are expensive, lead to unnecessary antibiotic treatment, and can be avoided by always drawing blood cultures first with sterile technique.
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