phlebotomy order of draw and tube additives

3 min read 29-09-2024

phlebotomy order of draw and tube additives

Phlebotomy is a critical process in healthcare that involves drawing blood for various tests, research, and treatment purposes. One of the key components of successful phlebotomy is the order of draw and tube additives, which are essential for ensuring the accuracy of laboratory results. This article will provide an overview of these concepts, their significance, and practical applications in a clinical setting.

What is the Order of Draw in Phlebotomy?

The order of draw refers to the specific sequence in which blood collection tubes should be filled during venipuncture to prevent cross-contamination of additives and ensure the integrity of laboratory tests.

Why is the Order of Draw Important?

Using the correct order of draw is essential for:

Preventing Contamination: Different additives in the blood collection tubes can interfere with tests and yield inaccurate results if they cross-contaminate.
Maintaining Test Integrity: Certain tests require specific additives to function correctly; thus, ensuring proper sequence is crucial for reliable diagnostic outcomes.

The Recommended Order of Draw

According to the Clinical and Laboratory Standards Institute (CLSI), the typical order of draw is as follows:

Blood Culture Bottles (Sterile): Used for microbiology tests.
Light Blue Top (Sodium Citrate): Used for coagulation tests (e.g., PT, aPTT).
Red Top (No Additive): Used for serum tests.
Gold or Tiger Top (SST): Contains a gel separator; used for serum tests and chemistry panels.
Green Top (Heparin): Used for plasma tests in chemistry.
Lavender Top (EDTA): Used for hematology tests and blood smears.
Gray Top (Potassium Oxalate/Sodium Fluoride): Used for glucose and lactate testing.

Practical Example

Imagine you are collecting blood samples from a patient for various tests: a PT test, a glucose level, and a complete blood count (CBC). If you accidentally draw the lavender top before the light blue top, the EDTA from the lavender tube could contaminate the sodium citrate in the blue top, potentially skewing the PT results.

Tube Additives: Their Role in Blood Collection

Each blood collection tube contains specific additives that serve unique purposes. Understanding these additives is crucial for healthcare professionals to obtain accurate test results.

Common Tube Additives and Their Functions

Sodium Citrate (Light Blue Top): Binds calcium, essential for coagulation tests.
Clot Activator (Red Top and Gold/Tiger Top): Promotes clotting to allow serum separation.
Heparin (Green Top): Acts as an anticoagulant for plasma testing.
EDTA (Lavender Top): Binds calcium and prevents clotting, making it ideal for hematology.
Potassium Oxalate and Sodium Fluoride (Gray Top): Inhibit glycolysis to preserve glucose levels.

Implications of Additives in Laboratory Testing

Using the wrong tube or not following the order of draw can lead to:

False Negatives/Positives: Contaminants can affect the results, leading to misdiagnosis.
Delayed Treatments: Incorrect results may lead to unnecessary repeat tests, causing delays in patient care.

Conclusion

Mastering the order of draw and understanding tube additives are essential skills for any phlebotomist or healthcare professional involved in blood collection. This knowledge not only ensures the accuracy of laboratory results but also plays a crucial role in patient safety and effective treatment planning.

Key Takeaways

Follow the Order of Draw: Adhering to the recommended sequence is vital to avoid contamination and ensure valid test results.
Know Your Additives: Familiarity with each tube's additives helps healthcare professionals select the appropriate tube for each test, ultimately enhancing the quality of patient care.

By following these practices, healthcare providers can minimize errors in blood sampling, leading to more accurate diagnostics and effective patient management.

This article incorporates widely accepted practices in phlebotomy and laboratory testing, referencing general guidelines set forth by various healthcare standards. It's important to stay updated with institutional protocols and any additional guidelines from your respective clinical laboratory for specific practices.