American Medical Certification Association (AMCA) Phlebotomy Practice Exam

What is a reason for a sample to be rejected when the light blue top is over or underfilled?

1. Quality not sufficient (QNS)

2. Inadequate specimen volume

3. Contamination of the sample

4. Incorrect labeling

The correct answer is: Quality not sufficient (QNS)

When a sample collected in a light blue top tube is either overfilled or underfilled, the primary reason for rejection often pertains to quality issues, which is reflected in the term "Quality not sufficient" (QNS). The light blue top tube is specifically designed for tests that require precise ratios of anticoagulant (sodium citrate) to blood, such as coagulation studies. An improper fill volume disrupts this critical ratio, potentially leading to inaccurate test results. When the specimen is either overfilled or underfilled, the anticoagulant may not work effectively. In the case of overfilling, there may be an excess of anticoagulant, while underfilling results in insufficient anticoagulant to preserve the sample. Both scenarios compromise the sample's quality, making it unsuitable for reliable analysis. Thus, the rejection is based on ensuring that only high-quality specimens are utilized for testing, which is vital for accurate diagnosis and treatment planning.