What Are The 7 Tubes of Blood Drawn?

Blood collection is a foundational process in medical diagnostics. Understanding the purpose and contents of each Blood-Collection-Tube is essential for healthcare professionals to ensure accurate testing and diagnosis. When multiple blood tests are ordered, it is common for phlebotomists to collect blood into seven different types of tubes, each color-coded and containing specific additives. In this article, we will explore the 7 essential blood collection tubes, their purposes, and important considerations when using them.

Overview of Blood-Collection-Tube Systems

A Blood-Collection-Tube is designed to preserve the blood sample in a specific way, depending on the test to be performed. These tubes are usually color-coded to indicate the presence or absence of additives such as anticoagulants, clot activators, or gel separators.

Proper identification and use of the right Blood-Collection-Tube not only ensure the accuracy of lab results but also prevent sample degradation. Mistakes in tube selection or order of draw can lead to sample contamination and unreliable test outcomes.

What Are the 7 Tubes of Blood Drawn?

Here is a detailed explanation of the seven commonly used blood collection tubes:

1. Light Blue Top Tube

• Additive: Sodium citrate (anticoagulant)

• Purpose: Used primarily for coagulation studies such as PT (Prothrombin Time) and APTT (Activated Partial Thromboplastin Time).

• Notes: It’s critical to fill this Blood-Collection-Tube precisely to ensure an accurate blood-to-additive ratio.

2. Red Top Tube

• Additive: No additive (sometimes clot activator)

• Purpose: Collects serum for chemistry, serology, and blood bank testing.

• Notes: Since it contains no anticoagulant, blood will clot naturally, allowing serum separation after centrifugation.

3. Gold Top Tube (or SST - Serum Separator Tube)

• Additive: Clot activator and gel for serum separation

• Purpose: Frequently used for chemistry panels and serology tests.

• Notes: After centrifugation, the gel creates a barrier between serum and cells.

4. Green Top Tube

• Additive: Heparin (sodium, lithium, or ammonium)

• Purpose: Plasma chemistry studies, particularly for stat tests due to its quick processing capabilities.

• Notes: Prevents clotting without interfering with most biochemical assays.

5. Lavender (or Purple) Top Tube

• Additive: EDTA (ethylenediaminetetraacetic acid)

• Purpose: Used for hematology tests like CBC, blood smears, and HbA1c.

• Notes: EDTA preserves cellular components, making it the gold standard for complete blood counts.

6. Gray Top Tube

• Additive: Potassium oxalate and sodium fluoride

• Purpose: Specifically designed for glucose testing and blood alcohol levels.

• Notes: The sodium fluoride inhibits glycolysis, stabilizing glucose levels for accurate measurements.

7. Yellow Top Tube

• Additive: Acid-citrate-dextrose (ACD) or Sodium Polyanethol Sulfonate (SPS)

• Purpose: Used for blood cultures or HLA phenotyping.

• Notes: ACD preserves red blood cells, while SPS supports bacterial growth for cultures.

Choosing the correct Blood-Collection-Tube is critical because each additive interacts differently with blood components, ensuring the preservation or preparation needed for the specific test.

Why Proper Blood-Collection-Tube Use Matters

Selecting the correct Blood-Collection-Tube during blood draw is vital for several reasons:

• Prevents Test Errors: Additives are selected based on their compatibility with different types of tests. Using the wrong tube can produce misleading results.

• Sample Integrity: Certain tests require plasma, others serum. Misusing tubes can result in hemolysis, clotting, or degradation.

• Efficiency: Proper tube usage reduces the likelihood of sample recollection, minimizing patient discomfort and laboratory workload.

Hunan Ruitai Medical offers a variety of Blood-Collection-Tube options, each manufactured to the highest standards. Our tubes ensure proper additive volumes, precise vacuum levels, and excellent sample preservation.

Our featured Blood Collection Tubes are made from high-quality PET material, offering strong chemical resistance, excellent visibility, and superior vacuum retention. Each tube is optimized to support specific diagnostic applications while maintaining the stability of blood samples for longer periods.

Tips for Correct Blood Draw Technique

Using multiple Blood-Collection-Tube types in a single draw requires careful attention:

1. Follow the Correct Order of Draw: Light blue, red/gold, green, lavender, gray, and yellow, to avoid cross-contamination of additives.

2. Gently Invert Tubes: Mix additives properly by gently inverting the tubes as per guidelines (usually 5–10 times).

3. Proper Labeling: Label tubes immediately after collection to avoid misidentification.

4. Use the Right Needle Size: Choose an appropriate needle gauge to ensure smooth blood flow and minimize hemolysis.

Following these guidelines ensures that each Blood-Collection-Tube performs its intended function, preserving the integrity of every blood sample collected.

Conclusion

Understanding the purpose and correct use of each Blood-Collection-Tube is crucial in the clinical laboratory setting. The seven tubes discussed—light blue, red, gold, green, lavender, gray, and yellow—are standard in medical blood collection, each serving a unique role based on its additive and intended analysis.

Whether you are expanding your medical facility or upgrading your blood collection systems, selecting the right Blood-Collection-Tube can make all the difference in obtaining precise, actionable laboratory results.