NHA Phlebotomy Certification Practice Exam

For what reason would a laboratory reject a specimen?

1. Clots in a lavender stopper tube

2. Collection in the wrong tube

3. Incompletely filled light-blue stopper tubes

4. Clots in a red stopper tube

The correct answer is: Clots in a red stopper tube

In laboratory settings, certain specimen handling standards must be adhered to ensure accurate testing results. Clots in a red stopper tube can lead to rejection of the specimen primarily because the presence of clots indicates that the sample may not adequately represent the liquid plasma or serum required for many tests. When a red stopper tube is used, it typically contains no additives that promote clotting; hence, the blood should clot naturally to separate the serum upon centrifugation. When clots are present in this tube, they can interfere with the laboratory’s ability to extract a clear serum sample, potentially leading to unreliable laboratory results. This ensures that any analysis performed is both accurate and valid for diagnosis, making the rejection of such a specimen necessary for maintaining the integrity of laboratory testing.