Order of Draw in Laboratory Testing: Understanding the Importance and Common Sequence for Accurate Results

Summary

• Following the correct order of draw is crucial for accurate laboratory results.
• The order of draw for collecting blood samples from multiple tubes in the United States typically follows a specific sequence.
• Understanding the order of draw can help healthcare professionals avoid Cross-Contamination and ensure the integrity of the samples.

Introduction

In the healthcare industry, accurate and reliable laboratory Test Results are essential for proper diagnosis and treatment of patients. When collecting blood samples for testing, healthcare professionals must follow specific protocols to ensure that the samples remain uncontaminated and yield accurate results. One key protocol that must be followed is the order of draw - the sequence in which blood samples are collected in multiple tubes. In the United States, there is a standardized order of draw that healthcare professionals must adhere to when collecting blood samples for laboratory testing.

Order of Draw

The order of draw is a standardized sequence that healthcare professionals follow when collecting blood samples from patients for laboratory testing. This sequence is designed to minimize the risk of Cross-Contamination between tubes and ensure the integrity of the samples. The order of draw is especially important when collecting blood samples for multiple tests, as using the wrong sequence can lead to inaccurate results.

Common Order of Draw

In the United States, the most commonly used order of draw when collecting blood samples for laboratory testing is as follows:

1. First tube: Blood Culture tubes
2. Second tube: Coagulation tubes (citrate tubes)
3. Third tube: Serum tubes without additives
4. Fourth tube: Heparin tubes
5. Fifth tube: EDTA tubes
6. Sixth tube: Glycolytic inhibitor tubes

Rationale Behind the Order of Draw

The order of draw is established based on the additives present in each tube and their potential to interfere with Test Results. By following this specific sequence, healthcare professionals can minimize the risk of contamination and ensure that each sample remains viable for testing. Here is a brief explanation of the rationale behind the common order of draw:

1. Blood Culture tubes: By collecting Blood Culture samples first, healthcare professionals reduce the risk of contaminating other tubes with microorganisms that may be present in the blood.
2. Coagulation tubes: Citrate tubes are used for coagulation studies and must be collected before other tubes to prevent Cross-Contamination with other additives.
3. Serum tubes without additives: These tubes are used for various chemistry tests and should be collected before tubes with additives to avoid interference with Test Results.
4. Heparin tubes: Heparin is an Anticoagulant that can affect certain tests, so these tubes should be drawn before tubes with EDTA or other additives.
5. EDTA tubes: EDTA is an Anticoagulant commonly used for hematology tests. Collecting these tubes after Heparin tubes ensures accurate results for both types of tests.
6. Glycolytic inhibitor tubes: These tubes are used for glucose testing and should be collected last to prevent contamination from other additives.

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. Healthcare professionals in the United States must adhere to the standardized sequence to minimize the risk of Cross-Contamination and ensure the integrity of the samples. By understanding the rationale behind the order of draw and following the established protocol, healthcare professionals can contribute to the delivery of high-quality patient care and improve patient outcomes.

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