Order of draw
The CLSI order for blood collection tubes, what each one is for, and a drill to learn it.
- 1Blood culture
Broth (bottles) or SPS (yellow tube)
Bacteria and fungi in the blood
Invert 8–10 (SPS tube)
- 2Light blue
Sodium citrate (3.2%)
Coagulation: PT/INR, aPTT, fibrinogen, D-dimer. Fill it all the way.
Invert 3–4
- 3Red or Gold (also red-gray tiger)
Clot activator; gold (SST) adds a gel separator
Serum: chemistry, immunology and serology
Invert 5 (glass red: none)
- 4Green or Light green
Lithium or sodium heparin; light green (PST) adds gel
Plasma chemistry: ammonia (on ice), lithium level (sodium heparin)
Invert 8–10
- 5Lavender (also pink, pearl)
EDTA (K2EDTA)
Hematology: CBC, HbA1c, ESR. Pink: blood type and antibody screen.
Invert 8–10
- 6Gray
Sodium fluoride and potassium oxalate
Glucose (fasting, timed), lactate, blood alcohol
Invert 8–10
Order: CLSI, for venipuncture. Inversions: BD. Follow your lab’s chart where it differs.
Tap the tubes in order of draw. Tubes in the same step go either way.
- Slot 1, empty
- Slot 2, empty
- Slot 3, empty
- Slot 4, empty
- Slot 5, empty
- Slot 6, empty
- Slot 7, empty
- Slot 8, empty
Why the order matters
A needle can pick up a trace of one tube’s additive and carry it into the next. The order keeps each additive away from the tests it would throw off.
- EDTA carried into a serum or heparin tube lowers calcium and magnesium and raises potassium, so lavender comes after them.
- Clot activator in plastic serum tubes can interfere with coagulation tests, so light blue comes before red and gold.
- Blood cultures go first, to keep them sterile.
Butterfly, and light blue first? Draw a discard tube.
A winged set’s tubing holds air. If light blue is your first tube, draw a discard tube first to fill that dead space, so the citrate tube gets the right amount of blood. It doesn’t need to fill. Use a tube with no additive, or another light blue.
Memory aid, not part of any standard: “Stop Light Red, Stay Put, Green Light Go.” Sterile cultures, light blue, red, SST (gold), PST (light green), green, lavender, gray.
Where sources differ
- Gel tubes. CLSI puts each gel tube in the same step as its plain one: gold with red, light green with green, pearl with lavender. WHO’s 2010 table lists them as separate steps, gold after red and light green after dark green. Either way they sit between light blue and lavender.
- Glass or plastic red. Plastic red tubes hold a clot activator, so they follow light blue. CLSI allows only a glass red tube with no additive, or a plastic one without clot activator, before light blue. That’s why older charts put red second.
- WHO’s table follows the 2003 standard. It adds a tube with no additive before light blue, for when tissue fluid could contaminate it, and puts yellow ACD between lavender and gray.
- Tubes CLSI doesn’t list, like yellow ACD, royal blue for trace elements and tan for lead, sit in different places on different labs’ charts. CLSI says to place them by what their additive could do to the next tube, so use your lab’s chart.
- The discard tube. BD: a tube with no additive or a coagulation tube. UF Health: a plain red top or a light blue top.
- Fingersticks and heelsticks go the other way: EDTA first, then other additive tubes, then serum (WHO; BD, citing CLSI). The chart above is for venipuncture.
- Inversions are BD’s counts, which UF Health uses too. Some labs use others, and WHO gives none.
- The standard. CLSI replaced GP41 (7th edition, 2017) with PRE02 (8th edition) in February 2025. Both are paywalled; the order here is CLSI’s own summary, and current BD and hospital charts match it.
Sources
- Order of Blood Draw Tubes and Additives · CLSI, 2019
- Blood collection points to practice (CLSI-recommended order of draw, GP41-A7) · BD, 2023
- BD Vacutainer Order of Draw for Multiple Tube Collections (VS5729-6) · BD, hosted by the Texas Department of State Health Services, 2010
- WHO guidelines on drawing blood: best practices in phlebotomy · World Health Organization, 2010
- Blood Collection Process: Venipuncture · UF Health Pathology Laboratories, University of Florida
- Order of Draw · VCU Health Department of Pathology, 2025
- Drawing the Line: The Rationale Behind Blood Tube Collection Order (Lab Medicine Rounds) · Mayo Clinic Laboratories, 2024
- BD Microtainer tube product page · BD
Learn phlebotomy in five-minute lessons.
Phlebotomy Exam Prep is planned for the NHA CPT. Start learning and the app builds your first lesson from the official sources.
Study help, not a procedure manual. Follow your lab’s order of draw.