Which tube color is typically used for coagulation tests?

The light blue tube is the correct choice for coagulation tests because it contains sodium citrate, an anticoagulant that helps prevent blood from clotting. This is essential for accurate coagulation testing, as it allows for the measurement of clotting factors without interference from the formation of clots. Sodium citrate binds calcium ions in the blood, which are necessary for the coagulation process, thus maintaining the blood in a liquid state for testing.

Using the light blue tube ensures that tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT) can be carried out effectively, providing precise results that reflect the patient's coagulation status. Other tubes serve different purposes; for instance, the red tube typically contains no additives and is used for serum tests, while the green tube contains heparin, which is more relevant for other types of tests. The purple tube usually contains EDTA as an anticoagulant and is mainly used for hematology tests, not coagulation studies.