The Importance of Proper Order of Draw in Blood Collection for Accurate Laboratory Testing Results

Summary

• Proper order of draw is crucial for accurate laboratory testing results.
• Incorrect order of draw can lead to sample contamination and inaccurate Test Results.
• The correct order of draw for collecting blood samples in the United States is: Blood Culture tubes, coagulation tubes, serum tubes, Heparin tubes, EDTA tubes, and finally, glycolytic inhibitor tubes.

Introduction

When it comes to collecting blood samples for laboratory testing, following the correct order of draw is essential in ensuring accurate and reliable results. The order of draw refers to the sequence in which different blood collection tubes are filled during a single Venipuncture procedure. This process is critical in preventing sample contamination and ensuring that Test Results are as accurate as possible.

Importance of Order of Draw

The order of draw is crucial for several reasons:

1. Prevents Cross-Contamination: Using the correct order of draw helps minimize the risk of sample contamination by ensuring that additives from one tube do not carry over to the next tube.
2. Ensures accurate results: Following the proper order of draw helps maintain the integrity of the blood sample, which is essential for obtaining accurate Test Results.
3. Complies with standard procedures: Adopting a standardized order of draw ensures consistency and adherence to best practices in blood collection, reducing the likelihood of errors.

The Correct Order of Draw for Blood Collection

In the United States, the recommended order of draw for collecting blood samples for laboratory testing is as follows:

1. Blood Culture tubes: These tubes are used to collect samples for microbiological testing to detect the presence of bacteria or fungi in the bloodstream.
2. Coagulation tubes: These tubes contain additives that prevent blood from coagulating and are used for tests such as Prothrombin Time (PT) and Activated Partial Thromboplastin Time (aPTT).
3. Serum tubes: These tubes are used to collect blood samples for tests that require serum, such as basic metabolic panels, liver function tests, and lipid profiles.
4. Heparin tubes: These tubes contain Heparin, an Anticoagulant that prevents blood from clotting, and are used for tests such as electrolyte panels and blood gases.
5. EDTA tubes: These tubes contain ethylenediaminetetraacetic acid (EDTA), which acts as an Anticoagulant by binding to calcium ions in the blood. EDTA tubes are used for tests that require whole blood or plasma, such as complete blood counts (CBC) and blood typing.
6. Glycolytic inhibitor tubes: These tubes are used to collect blood samples for tests that require accurate glucose measurements, as they contain additives that inhibit glycolysis, the breakdown of glucose in the blood sample.

Exceptions to the Order of Draw

While the above order of draw is generally recommended for most blood collection procedures, there may be exceptions based on specific test requirements or patient conditions. Healthcare Providers should always refer to the laboratory's guidelines and protocols when collecting blood samples to ensure the correct order of draw is followed.

Conclusion

Following the correct order of draw when collecting blood samples for laboratory testing is essential for ensuring the accuracy and reliability of Test Results. By adhering to the standardized sequence of filling blood collection tubes, Healthcare Providers can minimize the risk of sample contamination and obtain VALID Test Results that guide patient care decisions.

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