Materials and Additives of Vacuum Blood Collection Tubes

Vacuum blood collection tubes, commonly known as vacutainers, are made of various materials and may contain different additives to serve specific purposes during blood collection and processing. The main components of vacutainers include:

Tube Body: The tube body is typically made of glass or plastic. Glass tubes are often used for biochemical and serological tests, while plastic tubes are used for various applications, including hematology, coagulation, and immunology tests. Plastic tubes are lightweight, shatter-resistant, and provide better biohazard protection.

Rubber Stoppers: Vacuum tubes have rubber stoppers at the top, which act as self-sealing closures. The stoppers create a vacuum inside the tube, allowing blood to be drawn into the tube automatically without the need for manual aspiration.

Additives and Anticoagulants: Vacuum blood collection tubes may contain various additives and anticoagulants to prevent clotting or preserve the integrity of specific analytes. Common additives and their functions include:

a. EDTA (Ethylenediaminetetraacetic Acid): EDTA is an anticoagulant that chelates calcium ions, preventing blood from clotting. It is used in lavender-top tubes for hematological tests like complete blood counts (CBC) and blood cell differentials.

b. Sodium Citrate: Sodium citrate is an anticoagulant that binds to calcium ions, inhibiting the coagulation process. It is used in light blue-top tubes for coagulation studies like prothrombin time (PT) and activated partial thromboplastin time (APTT).

c. Heparin: Heparin is an anticoagulant that inhibits thrombin and other clotting factors. It is used in green-top tubes for various chemistry tests, such as ammonia levels and blood gas analysis.

d. Sodium Fluoride and Potassium Oxalate: These additives inhibit glycolysis and preserve glucose levels in blood samples. They are used in gray-top tubes for glucose tolerance tests and lactate measurements.

e. Gel Separation: Some tubes contain a gel material (e.g., silica gel) at the bottom. After blood collection, the tube is centrifuged, and the gel forms a barrier between the serum/plasma and cellular components, allowing for easy separation during testing.

Vacuum System: Vacuum tubes are equipped with a vacuum system that creates negative pressure inside the tube, ensuring that the correct volume of blood is drawn into the tube automatically when the needle pierces the stopper.

It's essential for healthcare professionals to be familiar with the specific additives and anticoagulants present in each vacutainer to ensure accurate and reliable test results. Different tubes are used for specific tests to avoid interference between additives and test results.