NHA Phlebotomy Certification Practice Exam

The ratio of blood to anticoagulant in a light blue stopper tube is:

1. 2:1.

2. 5:1.

3. 9:1.

4. 10:1.

The correct answer is: 9:1.

The correct answer is that the ratio of blood to anticoagulant in a light blue stopper tube is 9:1. This specific ratio is important because light blue stopper tubes contain sodium citrate as the anticoagulant, which is used primarily for coagulation studies. The standard 9:1 ratio means that for every 9 parts of blood, there is 1 part of anticoagulant. This ratio is crucial for obtaining accurate test results in coagulation tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). If the ratio is not maintained, it could lead to incorrect results due to either an excess of anticoagulant or insufficient anticoagulant to prevent clotting. Maintaining this precise ratio ensures that the blood sample is properly anticoagulated, allowing for reliable laboratory testing. Understanding the significance of this ratio helps phlebotomists perform their tasks accurately and understand the implications of sample handling and preparation in laboratory settings.