Steps In The Order Of Draw
When you go to the doctor's office or a lab to have blood drawn for testing, you may not realize that there is a specific order in which the different tubes must be filled. This is known as the Order of Draw, and it is important to follow this sequence to ensure accurate test results and to prevent sample contamination. In this article, we will discuss the steps in the Order of Draw and why each tube is filled in a specific order.
Why is the Order of Draw important?
The Order of Draw is a standardized process that is used to ensure the accuracy of blood test results. By following a specific sequence when filling blood collection tubes, healthcare professionals can minimize the risk of sample contamination and ensure that the test results are reliable. In addition, following the Order of Draw helps to prevent blood from one tube contaminating the sample in the next tube, which could lead to inaccurate test results.
Steps in the Order of Draw
There are several steps in the Order of Draw that must be followed when collecting blood samples for testing. These steps are as follows:
1. Yellow Tube
The first tube that should be drawn is the tube with the yellow cap, which contains an additive called ACD (acid citrate dextrose). This additive is used to prevent blood clotting and is typically used for tests that require whole blood, such as blood cultures or DNA testing.
2. Light Blue Tube
The second tube that should be drawn is the tube with the light blue cap, which contains citrate as an additive. This additive is used to prevent blood clotting by binding to calcium in the blood. Light blue tubes are typically used for tests that require plasma, such as coagulation studies.
3. Red Tube
The third tube that should be drawn is the tube with the red cap, which does not contain any additives. Red tubes are used for tests that require serum, such as blood glucose or cholesterol testing.
4. SST Tube (Gold or Tiger Top)
The fourth tube that should be drawn is the SST tube, which has either a gold or tiger top. This tube contains a gel separator that separates the serum from the cells after the blood has been centrifuged. SST tubes are typically used for tests that require serum, such as liver function tests or lipid panels.
5. Green Tube
The fifth tube that should be drawn is the tube with the green cap, which contains heparin as an additive. Heparin is used to prevent blood clotting by inhibiting the formation of thrombin. Green tubes are typically used for tests that require plasma, such as electrolyte panels or blood gas analysis.
6. Lavender Tube
The sixth tube that should be drawn is the tube with the lavender cap, which contains EDTA (ethylenediaminetetraacetic acid) as an additive. EDTA is used to chelate, or bind, calcium in the blood to prevent clotting. Lavender tubes are typically used for tests that require whole blood, such as complete blood counts or blood typing.
7. Gray Tube
The last tube that should be drawn is the tube with the gray cap, which contains an additive such as sodium fluoride or potassium oxalate. These additives are used to preserve glucose and inhibit glycolysis. Gray tubes are typically used for tests that require plasma, such as glucose testing.
Conclusion
Following the Order of Draw when collecting blood samples for testing is essential to ensure the accuracy and reliability of test results. By following a specific sequence when filling blood collection tubes, healthcare professionals can minimize the risk of sample contamination and ensure that the test results are reliable. It is important to understand the steps in the Order of Draw and why each tube is filled in a specific order to ensure the best possible outcomes for patients.
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