Importance of the Order of Draw
The order of draw is vital for minimizing the risk of cross-contamination and ensuring accurate test results. Different blood tests require specific tube types, and drawing blood in the wrong order can lead to erroneous lab results. The importance of adhering to the correct order includes:
- Prevention of contamination: Certain additives in tubes can interfere with tests if mixed incorrectly.
- Accuracy of results: Proper order ensures that specimens are collected in a way that reflects true biological conditions.
- Standardization: Following a consistent protocol across healthcare facilities fosters reliability in testing.
Order of Draw
The order of draw refers to the prescribed sequence in which blood collection tubes should be filled during venipuncture. Below is the commonly accepted order:
1. Blood Cultures: Used for detecting infections in the bloodstream.
2. Light Blue Top: Contains sodium citrate; used for coagulation tests.
3. Red Top: No additive; used for serum tests.
4. Gold or Tiger Top: Contains a gel separator; used for serum tests and some chemistry tests.
5. Green Top: Contains heparin; used for plasma tests.
6. Lavender/Purple Top: Contains EDTA; used for complete blood counts and blood smears.
7. Gray Top: Contains sodium fluoride and potassium oxalate; used for glucose testing.
Rationale for the Order of Draw
Each type of tube has a specific purpose and contains additives that can affect test results if they are not drawn in the correct order. For example, drawing a lavender top tube before a light blue top tube can lead to EDTA contamination in the coagulation tests, yielding inaccurate results.
Tube Additives and Their Functions
Each blood collection tube contains additives that serve specific functions related to the testing process. Below is a detailed breakdown of common tube types and their corresponding additives:
1. Blood Culture Tubes
- Additive: Nutrient broth
- Function: To promote the growth of microorganisms for culture and sensitivity testing.
2. Light Blue Top Tubes
- Additive: Sodium citrate
- Function: An anticoagulant that preserves the coagulation factors for tests such as PT (prothrombin time) and aPTT (activated partial thromboplastin time).
3. Red Top Tubes
- Additive: None
- Function: Allows for clotting to occur; used for serum tests such as hormone levels and certain chemistry tests.
4. Gold or Tiger Top Tubes
- Additive: Gel separator and clot activator
- Function: Facilitates clotting and separates serum from the clot for serum-based tests.
5. Green Top Tubes
- Additive: Heparin (either lithium or sodium)
- Function: An anticoagulant used for various tests, including plasma assays and certain chemistry tests.
6. Lavender/Purple Top Tubes
- Additive: EDTA (ethylenediaminetetraacetic acid)
- Function: An anticoagulant used for complete blood counts (CBCs) and blood smears.
7. Gray Top Tubes
- Additive: Sodium fluoride and potassium oxalate
- Function: Sodium fluoride inhibits glycolysis, making it suitable for glucose testing; potassium oxalate serves as an anticoagulant.
Phlebotomy Order of Draw Worksheet
Creating a worksheet can help phlebotomists and laboratory staff remember the order of draw and the tube additives. Here’s a sample worksheet template:
| Tube Color | Additive | Test Type |
|-----------------|---------------------------------|-----------------------------|
| Blood Cultures | Nutrient broth | Microbial culture |
| Light Blue | Sodium citrate | Coagulation tests |
| Red | None | Serum tests |
| Gold/Tiger Top | Gel separator, clot activator | Serum tests |
| Green | Heparin | Plasma tests |
| Lavender/Purple | EDTA | CBC, blood smears |
| Gray | Sodium fluoride, potassium oxalate | Glucose tests |
Using the Worksheet
Phlebotomists can refer to this worksheet during blood collection procedures to ensure they are following the correct order of draw. It can also serve as a training tool for new staff members or as a quick reference in high-pressure situations.
Best Practices for Blood Collection
To maintain the integrity of the blood samples and ensure accurate results, phlebotomists should follow these best practices:
- Prepare the patient: Confirm the patient's identity and explain the procedure to alleviate anxiety.
- Use proper technique: Follow aseptic techniques to minimize the risk of contamination.
- Label tubes immediately: Ensure that each tube is labeled appropriately after collection to avoid mix-ups.
- Follow the order of draw: Adhere to the established order to prevent cross-contamination of additives.
- Monitor patient reactions: Observe for any adverse reactions during and after blood collection.
Conclusion
Understanding the phlebotomy order of draw and tube additives worksheet is essential for ensuring reliable laboratory results. By following the correct sequence and using the appropriate collection tubes, healthcare professionals can enhance the accuracy of blood tests and improve patient care. Continuous education and training on these protocols are vital for maintaining high standards in phlebotomy practice.
Frequently Asked Questions
What is the correct order of draw for blood collection in phlebotomy?
The correct order of draw is: Blood culture tubes, Citrate tubes (light blue), Serum tubes (red), Heparin tubes (green), EDTA tubes (lavender), and Oxalate/fluoride tubes (gray).
Why is it important to follow the order of draw in phlebotomy?
Following the order of draw minimizes the risk of cross-contamination between different additives in the tubes, which can affect test results.
What are the common additives found in phlebotomy tubes?
Common additives include sodium citrate (light blue), clot activator (red), heparin (green), EDTA (lavender), and potassium oxalate with sodium fluoride (gray).
What is the purpose of using a serum separator tube (SST)?
A serum separator tube (SST) contains a gel that separates serum from the blood cells after centrifugation, facilitating easier collection for serum testing.
How does the presence of EDTA in lavender tubes affect blood samples?
EDTA acts as an anticoagulant by binding calcium in the blood, preventing clotting and making it suitable for hematology tests.
What should you do if you accidentally draw blood into the wrong tube?
If you draw blood into the wrong tube, discard the sample and redraw into the correct tube, ensuring to follow proper order of draw.
What is the role of the additive sodium citrate in blood collection?
Sodium citrate is an anticoagulant that prevents blood from clotting, making it essential for coagulation studies.
How can improper order of draw impact laboratory results?
Improper order of draw can lead to erroneous test results, such as falsely elevated or decreased levels of certain analytes due to contamination from tube additives.
