If you’re studying phlebotomy, or if you’re already a working phlebotomist, one of the things you should know is the Order of Draw. This is a system for drawing blood for diagnostic testing, when there are several tubes of blood to be collected. The order is important, as each tube will be analyzed for a specific purpose. Usually, the collection tubes are color-coded, as they are pre-treated with special compounds that have different effects on the blood that help preserve the integrity of the sample.
The Order of Draw helps prevent cross-contamination so the diagnostic results are accurate.
The Correct Order of Draw for Blood Samples
Blood samples are meant to be collected in a specific order to prevent cross-contamination from additives. Whether you are drawing blood via tube holder, syringe, or tubes pre-evacuated at the time of sample collection, the Order of Draw always remains the same. Here is the correct order in which to collect patient blood samples.
Keep in mind, you may not use all of these tubes at any one time, in fact, using all of them will probably be uncommon. But it’s good to know the right order as a professional phlebotomist, just in case.
1. Blood Culture (Light Yellow or Yellow-Black)
Sometimes the color can vary. For taking blood cultures. These are sterile tubes with no additives whatsoever.
2. Sodium Citrate (Light Blue)
These tubes are coagulation tubes and must be filled to a certain point to have the correct ratio of sodium citrate to blood. The sodium citrate prevents clotting by binding to calcium in the blood. During the testing process, the medical lab can introduce a reagent containing calcium to begin the clotting cascade and test coagulation of the blood.
3. Chemistry Tube for Serum (Red, Red-Gray)
Serum tubes, in most cases, without clot activation gel. This tube is used to test the serum in the blood, which is the liquid portion of the blood left when a clot is formed. This is not a commonly used test, but there are certain tests that require this draw.
4. SST aka Serum Separator Tube (Gold)
Sometimes Red and Black striped aka Tiger-Top. Serum tubes with clot activation gel. Used to check for antigen antibodies. This is usually sent to an outside diagnostic lab and not tested in the hospital. Not a primary tube, but not entirely uncommon.
5. Heparin (Green)
Lithium Heparin (Light Green), Sodium Heparin (Dark Green). Sometimes called a plasma separation tube (PST). This tube is very commonly used for a wide range of tests, which can usually be done in the hospital. Some tests may require the green tube to be immediately put on ice to preserve cellular status at time of draw. Some tests include ammonia levels, ionized calcium, or lactate levels.
6. EDTA (Lavender/Purple)
Used for cellular studies, testing hemoglobin, white blood cells count, platelet count, A1C (blood sugar), red blood cell sedimentation aka Erythrocyte Sedimentation Rate (ESR). The tubes are treated with ethylenediaminetetraacetic acid (EDTA) which preserves the morphology of the cells, meaning they retain their original shape for study under a microscope. Also binds calcium to prevent calcium.
7. Blood Type Sample (Pink)
Very similar to the Lavender tube, it is also treated with EDTA and is high in potassium. These are typically sent to the blood bank to test for a patient’s blood type.
8. Sodium Fluoride (Gray)
Sodium fluoride or potassium oxalate used as a glycolytic inhibitor. This tube is used to check lactate levels (lactic acid) and ethanol levels. Can also be used if the patient needs to test a fasting glucose level.
9. ACD Solution (Bright Yellow)
Acid citrate dextrose (ACD) anti-clotting, used for DNA testing and other applications. Can be also used for HIV testing.
| Blood Draw Order | Tube Top Color | Chemical Additive | Application |
|---|---|---|---|
| 1 | Yellow, Black, color varies | Nutrients to grow culture, agent to slow phagocytosis and stop bactericide by white blood cells | Blood culture, sterile collection vials |
| 2 | Blue | Sodium Citrate | Coagulation tube |
| 3 | Red | Clot Activator | Testing serum in the blood |
| 4 | Gold, sometimes Tiger-Top | Gel to separate cells from serum, may or may not contain clot activator | Separates cells from serum |
| 5 | Light Green, Dark Green | Heparin compounds as anticoagulant, and plasma separator agent | Used to separate plasma from cells, testing for cardiac markers, and a wide range of tests. |
| 6 | Lavender / Purple | EDTA (ethylenediaminetetraacetic acid) | Hematology tube. Preserves cell morphology, measuring cell levels in blood aka Complete Blood Count (CBC); sedimentation rate to measure inflammation. |
| 7 | Pink | EDTA | Testing for patient blood type. |
| 8 | Gray | Sodium Fluoride and Potassium Oxalate | Glycolytic inhibitor, prevents blood cells using glucose and anticoagulant. Used for Glucose Tolerance Test (GTT) and Blood Alcohol Content (BAC), primary use is measuring glucose content in the blood. |
| 9 | Yellow | ACD-A, ACD-B | Genetic and DNA testing, Platelet-Rich-Plasma prep, testing for organ matching |
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Why Is It Important to Follow the Order of Draw?
Blood is drawn into different tubes treated with specific additives that serve different purposes for diagnostic testing. Following the correct blood draw order prevents additives carrying over into the next tube. This preserves the integrity of each blood sample for their intended purpose. There are further reasons to memorize the Order of Draw and follow it systematically.
Preventing Cross-Contamination
Each tube is treated with additives that have different effects on the blood sample. Some tubes have clot activators, others have compounds to prevent coagulation. Drawing in the correct order prevents additives contaminating subsequent tubes, resulting in more accurate diagnostic testing.
The phlebotomist must consider the order of all tubes (if not listed above). If there is carryover of one additive to the next tube, it can alter the test results. For example, a clot activation agent can interfere with coagulation testing. The only tubes that can be collected before a coagulation tube (light blue) are the blood culture tube, glass serum tubes without any additives, and any plastic tubes without a clot activation additive.
Minimizes the Degradation of Red Blood Cells
The cellular breakdown of red blood cells is known as hemolysis, and this can cause inaccuracies in test results. Maintaining the correct Order of Draw minimizes hemolysis, as some tubes are designed to prevent red blood cell degradation.
Sample Integrity
Many blood draws rely on sample integrity, and drawing in the correct procedural order helps maintain the purity of patient samples for accurate diagnostic analysis..
Quick, Error-Free Patient Visit
Following the Order of Draw makes patient blood collection a quick, efficient procedure. Drawing large amounts of blood for testing can be an anxiety-inducing experience, and when the phlebotomist is organized, the process is safe, quick, and error-free.
Remembering Order of Draw Using an Acronym
You can use any acronym you choose to remember the proper order of tubes in the Order of Draw. You can make up one that works best for you. Here is one that I find easy to remember. Come Be Ready to Go, Good Luck Playing Games, Ya'll.
- Cultures = Come
- Blue = Be
- Red = Ready (to)
- Gold = Go
- Green = Good
- Lavender = Luck
- Pink = Playing
- Gray = Games
- Yellow = Ya’ll
Learn Phlebotomy and Get Certified at Campus Sacramento
If you’re excited about starting a healthcare career, Campus Sacramento can help you learn phlebotomy and earn your CPT-I certification. We offer a Medical Assisting with Phlebotomy program for MA’s in training, and a Phlebotomy training program that will help you earn certification in about 12 weeks. Both of these programs are for students in the Sacramento area. For more information on class schedules, start dates, and financial aid, contact our friendly Admissions team or call 888-675-2460.