The order of draw is the sequence for filling tubes when you collect more than one from a single venipuncture. It comes up on phlebotomy and medical assistant exams and on your first day at work.
The order, tube by tube
| Order | Tube | Additive | Common cap color | Invert |
|---|---|---|---|---|
| 1 | Blood culture bottles | Culture media (sterile) | Bottle | Per bottle instructions |
| 2 | Citrate tube | Sodium citrate | Light blue | 3 to 4 times |
| 3 | Serum tube | Clot activator | Red | 5 times |
| 3 | SST gel separator tube | Clot activator and gel | Gold or red and gray | 5 times |
| 3 | Rapid serum tube (RST) | Thrombin-based clot activator and gel | Orange | 5 to 6 times |
| 4 | Heparin tube | Lithium or sodium heparin | Green | 8 to 10 times |
| 4 | PST gel separator tube | Lithium heparin and gel | Light green | 8 to 10 times |
| 5 | EDTA tube | EDTA | Lavender or pink | 8 to 10 times |
| 5 | PPT gel separator tube | K2EDTA and gel | White | 8 to 10 times |
| 6 | Fluoride tube | Sodium fluoride | Gray | 8 to 10 times |
Tubes that share a number go in the same place in the order. Cap colors can differ by manufacturer, so go by the additive printed on the label, not the color alone.
TODO: BD’s chart shows cap colors as swatches only. Have a phlebotomy reviewer confirm the colors, and the 8 to 10 inversions against BD’s current tube guide, before launch.
Tips from the same BD chart
- Winged set with a citrate tube first. Draw a discard tube first. It clears air from the tubing so the citrate tube fills to the right volume.
- Winged set with blood cultures. Fill the aerobic bottle before the anaerobic bottle.
- Fill volume. Fill each tube to its marked volume so the blood and additive mix in the right ratio. This matters most for citrate tubes used for coagulation tests.
- Mixing. Gently invert each tube as soon as it comes off the holder. One inversion means turning the tube upside down and back. Shaking can cause hemolysis, which breaks down red blood cells.
- Tourniquet. Leave it on for no more than 1 minute.
BD’s chart follows the CLSI GP41 standard. It also says to always follow your facility’s protocol for order of draw.
Sources
- Becton, Dickinson and Company (BD), Blood collection points to practice and tips for success (BD-95825). The tube order, which follows CLSI GP41, the number of inversions for each tube, and the winged-set and mixing tips. Checked October 15, 2026.