Evacuated Blood Collection Tube Guide

Evacuated blood collection tubes are essential tools in medical laboratories, used for drawing and storing blood samples for testing. These tubes help maintain the integrity of the blood sample, ensuring accurate diagnostic results. Whether you're a healthcare professional or someone learning about lab equipment, this guide will walk you through everything you need to know about evacuated blood collection tubes.

What is an Evacuated Blood Collection Tube?

An evacuated blood collection tube is a sterile, glass or plastic container with a vacuum seal that allows blood to flow into it when the vein is punctured with a needle. The vacuum ensures that the correct volume of blood is drawn into the tube. These tubes are commonly used in hospitals, clinics, and diagnostic laboratories for various blood tests.

Types of Evacuated Blood Collection Tubes

Evacuated blood collection tubes come in different types, depending on the tests they are designed for. The main difference between them lies in the additives inside the tube and their color-coded caps, which indicate the type of additive. Here are the common types:

1. Plain Tubes (Red Cap)

Plain evacuated blood collection tubes contain no additives. They are primarily used for collecting serum, which is needed for tests like serology, blood chemistry, and hormonal analysis. Once the blood sample is collected, it is allowed to clot, and the serum can be separated by centrifugation.

2. Sodium Citrate Tubes (Light Blue Cap)

These tubes contain sodium citrate, an anticoagulant that prevents blood from clotting. They are mainly used for coagulation tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). Citrate tubes maintain the stability of the clotting factors in the blood sample.

3. Heparin Tubes (Green Cap)

Heparin is an anticoagulant that prevents blood from clotting by inactivating thrombin. Heparin tubes are used for plasma-based tests, including blood gas analysis and some clinical chemistry tests. They are often used when a quick separation of plasma is required.

4. EDTA Tubes (Lavender or Purple Cap)

EDTA (ethylene diamine tetraacetic acid) is a powerful anticoagulant that binds to calcium, preventing clotting. EDTA tubes are used for hematology tests, including complete blood counts (CBC), blood typing, and crossmatching. These tubes preserve the morphology of blood cells and maintain cellular integrity for microscopic examination.

5. Gel Separator Tubes (Gold or Tiger-Top Cap)

These tubes contain a gel that separates the serum or plasma from the blood cells during centrifugation. They are commonly used for routine chemistry tests and serum-based tests. The gel provides an effective barrier that maintains the stability of the sample and prevents contamination between the serum and cells.

6. Fluoride Oxalate Tubes (Gray Cap)

Fluoride oxalate tubes contain sodium fluoride and potassium oxalate. These additives are used to preserve glucose in the blood, preventing glycolysis. They are primarily used for blood glucose testing, lactate measurement, and other tests where the preservation of glucose levels is critical.

How to Use an Evacuated Blood Collection Tube

Using an evacuated blood collection tube properly is essential to obtaining accurate test results. Here’s a basic overview of the steps involved in using these tubes:

1. Prepare the Patient: Before collecting the blood sample, ensure the patient is in a comfortable position. Apply a tourniquet to the upper arm to help identify a vein.

2. Select the Appropriate Tube: Choose the right tube based on the required test and additives (e.g., plain, heparin, EDTA).

3. Draw the Blood: Insert the needle into the patient's vein. The vacuum inside the tube will automatically draw the required amount of blood. Ensure you don’t overfill the tube, as the proper blood-to-additive ratio is crucial.

4. Mix the Sample: Gently invert the tube several times to ensure the additive (if present) is well-mixed with the blood. This helps prevent clotting or separation issues.

5. Label the Tube: Clearly label the tube with the patient's information, test type, and collection time. This helps avoid any errors in identification.

6. Transport the Sample: Once collected, the sample should be transported to the laboratory under the appropriate conditions to ensure its integrity.

Best Practices for Storing Evacuated Blood Collection Tubes

The storage of vacuum blood collection tubes is crucial for maintaining sample quality. Follow these guidelines for proper storage:

• Temperature Control: Store blood collection tubes at the recommended temperature. Some tubes may need to be refrigerated or kept at room temperature, depending on the type of additive.

• Avoid Direct Sunlight: Exposure to direct sunlight can degrade the sample or interfere with certain test results.

• Proper Sealing: Ensure the tube cap is securely closed to prevent leakage or contamination of the sample.

Common Problems and How to Avoid Them

While using evacuated blood collection tubes is generally straightforward, certain issues can arise. Here are some common problems and tips on how to avoid them:

1. Hemolysis (Rupture of Red Blood Cells)

Hemolysis can occur if the blood sample is mishandled, such as through excessive shaking or using too small a needle. To avoid this, always handle the tube gently and ensure the correct needle size is used.

2. Underfilled Tubes

Underfilling the tube can lead to inaccurate test results, especially when the additives are not properly mixed with the blood. Always ensure the tube fills to the indicated line.

3. Incorrect Tube Selection

Using the wrong tube can result in inaccurate or invalid test results. Always check the test requirements before selecting the tube type and ensure the correct additives are present.

Conclusion

Evacuated blood collection tubes are vital tools in modern healthcare and laboratory settings. Understanding the different types of tubes, their uses, and best practices ensures accurate blood collection and proper testing. Whether you’re collecting a sample for routine blood work, glucose testing, or coagulation studies, choosing the right tube is essential for obtaining reliable results. Always follow proper handling and storage techniques to maintain the integrity of your blood samples.