NHA Phlebotomy Certification Practice Exam

What is the preferred order of draw for multiple tube collections?

1. Red, blue, green, lavender

2. Blue, red, green, lavender

3. Red, green, lavender, blue

4. Blue, green, lavender, red

The correct answer is: Red, blue, green, lavender

The preferred order of draw for multiple tube collections is essential for preventing cross-contamination of additives between tubes, which can interfere with test results. The correct order typically begins with tubes that do not contain additives, moves through anticoagulant tubes, and ends with those that contain anticoagulants or preservatives. In the recommended sequence, the red tube, which typically contains no additives, is drawn first to minimize the risk of additive contamination. This is followed by the blue tube, which contains sodium citrate, an anticoagulant used primarily for coagulation studies. Next in line is the green tube, which contains heparin, another type of anticoagulant. Finally, the lavender tube is drawn, which typically contains EDTA, an anticoagulant used for hematological studies. This systematic order is designed to ensure that additive interactions do not compromise the integrity of the blood samples, thereby improving the reliability of laboratory results.