Which of the following tubes contains an anticoagulant for coagulation testing?

The light blue tube is specifically designed for coagulation testing because it contains sodium citrate, which acts as an anticoagulant. This additive prevents the blood from clotting by binding calcium in the sample, allowing for accurate assessments of coagulation parameters, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT).

Understanding the role of anticoagulants in different tubes is crucial for phlebotomists as it affects the results of various laboratory tests. Other tubes, such as the green tube, typically contain heparin, which is also an anticoagulant but is not the primary choice for coagulation profiles. The yellow tube may contain various substances depending on the specific type, but often it's used for blood cultures or specific assays and does not align with standard coagulation testing practices. Lastly, the red tube typically does not contain any anticoagulant, as it is often used for serum tests where clotting is required. This distinction is important for ensuring that blood samples yield valid and reliable results based on the tests being performed.