The Vacutainer system is a standardized method for collecting blood samples, though “Vacutainer” is technically a brand name for the closed, evacuated tube blood collection system. This technology allows for the efficient and safe retrieval of blood for laboratory tests. The primary purpose of this system is to ensure the integrity of the collected sample and protect both the patient and the healthcare worker during phlebotomy.
How the System Works
The functionality of this blood collection method relies on three main components: a specialized needle, a plastic holder, and the evacuated tube itself. The needle is double-ended, featuring a sharp tip for venipuncture and a shorter, rubber-sleeved tip designed to pierce the rubber stopper of the collection tube within the adapter.
The plastic holder, or adapter, secures the needle and receives the collection tube. Once the outer needle is placed in the patient’s vein, the healthcare worker pushes the evacuated tube into the holder, puncturing its stopper with the inner needle. This action breaks the vacuum seal within the tube, creating a negative pressure differential.
The tube’s pre-measured vacuum automatically draws blood from the vein until the vacuum is exhausted. This design ensures that a precise, predetermined volume of blood is collected, which is crucial for maintaining the correct ratio of blood to any internal additives. Once full, the tube is removed, and another tube can be inserted for multiple collections without a second skin puncture.
Understanding the Color Codes
The rubber cap on each collection tube features a specific color, which serves as a universal code indicating the tube’s internal chemistry. These color codes inform the medical professional about the presence or absence of chemical additives designed to stabilize the blood sample for specific laboratory tests. Using the wrong color-coded tube can render a sample unusable, leading to inaccurate results or requiring a re-draw.
For example, a Lavender-top tube contains the anticoagulant Ethylenediaminetetraacetic acid (EDTA). EDTA stops clotting by binding to calcium ions, making this tube suitable for whole blood tests like a Complete Blood Count (CBC). In contrast, a Red-top tube may contain no additive, allowing the blood to clot naturally, or it may contain a clot activator. The resulting liquid, known as serum, is used for chemistry and serology tests.
The Light Blue-top tube contains sodium citrate, an anticoagulant required for coagulation studies, such as Prothrombin Time (PT) and Activated Partial Thromboplastin Time (aPTT). Tubes with a Gold or Tiger-top contain a clot activator and a separation gel. This gel physically barriers the serum from the blood cells after centrifugation, ensuring the sample remains in the appropriate state for accurate analysis.
Safety and Handling Procedures
The Vacutainer system incorporates several features and protocols to enhance safety during blood collection. Many modern needles are equipped with safety-engineered devices, such as retractable mechanisms or protective shields that slide over the sharp point after withdrawal. These features minimize the risk of accidental needlestick injuries for the healthcare worker, reducing exposure to bloodborne pathogens.
Standard hygiene protocols, often called Universal Precautions, are followed to protect both the patient and the collector. This includes the mandatory use of personal protective equipment, such as gloves and eye protection, to guard against potential blood splatter. Preventing cross-contamination between different tubes is managed by following a specific “order of draw” sequence when collecting multiple samples.
After the procedure is complete, the entire used unit—the needle and the holder—must be disposed of immediately. They are placed directly into a designated puncture-resistant biohazard container, known as a sharps container. This ensures that the contaminated sharp is secured and removed from the clinical environment without further handling.