Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam 2025 - Free Medical Laboratory Science Practice Questions and Study Guide

The option stating that a plain blood collection tube that is silicone treated and contains a gel provides a barrier between clot and serum is correct because the gel in such tubes serves a specific purpose during centrifugation. When the blood is allowed to clot, the gel creates a physical barrier between the solid clot formed and the liquid serum at the top of the tube. This separation is crucial for obtaining clear serum samples for testing, as it prevents any contamination from the clot after centrifugation.

In the context of blood collection tubes, the distinction between serum and plasma is also significant. Plasma includes clotting factors, while serum does not; hence, the presence of a gel barrier in these tubes ensures the collection of serum, which is often required for various laboratory tests.

The other options describe processes or uses of blood collection tubes that do not accurately apply to a silicone-treated tube with gel. For example, the idea of standing for at least an hour for necessary centrifugation does not align with standard practices, as centrifugation is generally expected to occur sooner, depending on the specifics of the test. Similarly, the cross-match procedures typically require specific tube types that may not include silicone-treated tubes with gel, which is designed for serum separation.