Which type of tube does not contain anticoagulants?

The red-topped tube is specifically designed for collecting serum samples and does not contain any anticoagulants. The absence of anticoagulants allows the blood to clot, facilitating the separation of serum from the blood cells after centrifugation. This is crucial for various laboratory tests that require serum rather than whole blood.

In contrast, the other tubes mentioned have anticoagulants that serve specific purposes in laboratory testing. For example, green-topped tubes contain heparin, which prevents clotting, and are commonly used for tests requiring plasma. Blue-topped tubes contain sodium citrate, also preventing coagulation and typically used for coagulation studies. Lavender-topped tubes have EDTA, which is an anticoagulant used primarily for hematology tests. Therefore, understanding the contents and intended uses of different tube types is essential for proper specimen collection and handling in clinical settings.