What is a common use for the blue blood collection tube?

The blue blood collection tube is commonly used for testing coagulation factors. This tube contains sodium citrate as its anticoagulant, which is critical for preserving the blood's ability to coagulate when a sample is collected. The sodium citrate works by binding calcium ions in the blood; calcium is essential for the coagulation process. This ensures that when the sample is analyzed, it accurately reflects the coagulation status of the patient.

Coagulation tests such as PT (Prothrombin Time) and aPTT (Activated Partial Thromboplastin Time) require samples taken in a blue tube to reliably assess clotting capabilities. The precise volume of blood to citrate is important, so there are usually fill lines on these tubes to ensure proper ratios are maintained.

In contrast, the other options involve different types of analyses or collection practices. Serum collection requires a tube that does not contain an anticoagulant, while cultures typically need a specific medium that supports the growth of microorganisms. Blood gas analyses usually require a different type of collection tube that is designed to maintain the gas composition of the blood sample during analysis.