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General product and laboratory-practice information only, not medical advice. Your facility’s written procedure and the tube manufacturer’s instructions govern what staff actually do.
Short answer: what is the order of draw for venipuncture?
The order of draw is the sequence in which blood collection tubes are filled during one venipuncture so that additives from one tube do not carry into the next. CLSI’s published sequence is: blood culture, sodium citrate, serum (with or without clot activator or gel), heparin, EDTA, then sodium fluoride/potassium oxalate. CLSI states the order is the same whether blood is collected by syringe, tube holder or preevacuated tubes.
Definition and scope: order of draw in phlebotomy
In phlebotomy, “order of draw” means the fixed sequence for filling multiple tubes from a single venous collection. It is a laboratory-quality rule, so it matters to everyone who writes collection procedures, stocks tubes or receives specimens, not only to the person collecting. The same question is often phrased as the order of draw for a phlebotomist, the correct order of draw for venipuncture, or the venipuncture order of draw; these all refer to the same sequence. It applies to venous collection only: capillary collection follows a different order.
The CLSI sequence
CLSI published this sequence in its blog article “Order of Blood Draw Tubes and Additives” (19 March 2019). CLSI gives the closure colours as examples (“eg”), not as the definition of each position.
| Position | Tube (CLSI wording) | Example closures named by CLSI |
|---|---|---|
| 1 | Blood culture tube or bottle | Not colour-specified |
| 2 | Sodium citrate tube | Blue |
| 3 | Serum tubes, including those with clot activator and gels | Red, red-speckled, gold |
| 4 | Heparin tube with or without gel | Dark green, light green, speckled green |
| 5 | EDTA tube with or without gel separator | Lavender, pearl, pink |
| 6 | Sodium fluoride/potassium oxalate glycolytic inhibitor | Gray |
For additive details by tube colour, see the blood draw tube colors chart.
Why the order exists: additive carryover
CLSI gives the purpose as avoiding “cross-contamination of the sample by additives found in different collection tubes.” If a tube containing one additive is filled before another, a trace of that additive can reach the next tube and alter the results obtained from it.
Syringe, tube holder and evacuated tubes
CLSI states that the order of draw is the same for specimens collected by syringe, by tube holder, or into preevacuated tubes. Changing the collection device does not change the sequence. Device choice is a separate question; see butterfly needle vs straight needle for venipuncture.
Exceptions and tubes not on the list
Plastic serum tubes and coagulation testing
CLSI notes that “plastic serum tubes containing a clot activator may cause interference in coagulation testing.” According to CLSI, only blood culture tubes, glass nonadditive serum tubes, or plastic serum tubes without a clot activator may be collected before the coagulation (citrate) tube. Background on that tube is in the coagulation tubes guide.
Tubes CLSI does not list
For tubes not in the sequence, CLSI says placement should take into consideration the potential for their additive to alter results obtained from the next tube if carryover were to occur. In practice this is a question for the laboratory that owns the test, not a default for the collector to improvise.
Where it matters for labs, clinics and supply decisions
A written order of draw is only as reliable as the documents behind it. A practical checklist for a laboratory or clinic that stocks venipuncture tubes:
- Keep one controlled copy of the sequence in the facility procedure, stating which source it follows (for example the CLSI sequence above) and the date it was last reviewed.
- Hold the tube manufacturer’s chart or instructions for each tube type in use, and compare it with the facility sequence.
- When a new tube brand, tube type or additive enters the supply list, re-check where it falls in the sequence before it reaches the collection area. Substituting one brand for another is a change to be reviewed, not assumed equivalent; see the phlebotomy lab supply checklist.
- Place the sequence where collection happens, in the same wording as the procedure, so there is one version in circulation.
- Keep capillary collection, which has its own order, documented separately from venous collection.
Common misunderstandings
- “The order depends on the needle or syringe.” CLSI states it is the same for syringe, tube holder and preevacuated tubes.
- “Tube colour alone defines the order.” CLSI gives colours only as examples (“eg”); its sequence is written by tube type and additive.
- “Any serum tube can go before a coagulation tube.” Per CLSI, plastic serum tubes with a clot activator may interfere with coagulation testing.
- “Capillary and venous order are the same.” Capillary collection has its own order; see the capillary blood collection guide.
FAQ
What is the order of draw?
It is the sequence for filling collection tubes in one blood draw so additives do not carry from one tube to the next. CLSI lists blood culture, sodium citrate, serum, heparin, EDTA, then sodium fluoride/potassium oxalate.
What is the order of draw in phlebotomy?
The same CLSI sequence applies to venous collection in phlebotomy. It is applied the same way for syringe, tube holder and preevacuated tube collection.
What is the order of draw for a phlebotomist?
A phlebotomist follows the sequence set in their facility’s procedure, which should match a recognised source such as the CLSI sequence and the tube manufacturer’s instructions. This page is general information and not training or medical advice.
Sources
- CLSI, “Order of Blood Draw Tubes and Additives,” blog article, 19 March 2019, https://clsi.org/about/blog/order-of-blood-draw-tubes-and-additives/ (checked 2026-11-04). The article lists CLSI GP41, Collection of Diagnostic Venous Blood Specimens, as a related resource.
