Vacutainer
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A vacutainer
Vacutainer tubes were invented by Joseph Kleiner in 1949.
Principles
The Vacutainer needle is double-ended: the inner end is encased in a thin rubber coating that prevents blood from leaking out if the Vacutainer tubes are changed during a multi-draw, and the outer end which is inserted into the vein. When the needle is screwed into the translucent plastic needle holder, the coated end is inside the holder.
When a tube is inserted into the holder, its rubber cap is punctured by this inner needle and the vacuum in the tube pulls blood through the needle and into the tube. The filled tube is then removed and another can be inserted and filled the same way. The amount of air evacuated from the tube predetermines how much blood will fill the tube before blood stops flowing.
Each tube is topped with a color-coded plastic or rubber cap. Tubes often include additives that mix with the blood when collected, and the color of each tube's plastic cap indicates which additives it contains.
Blood collection tubes expire because over time the vacuum is lost and blood will not be drawn into the tube when the needle punctures the cap.
Types of tubes
Vacutainer tubes may contain additional substances that preserve blood for processing in a medical laboratory. Using the wrong tube may make the blood sample unusable for the intended purpose. These additives are typically thin film coatings applied using an ultrasonic nozzle.
The additives may include
The meanings of the various colors are standardized across manufacturers.[5][6][7]
The term order of draw refers to the sequence in which tubes should be filled. The needle which pierces the tubes can carry additives from one tube into the next, so the sequence is standardized so that any cross-contamination of additives will not affect laboratory results.[7]
Tube cap color or type in order of draw | Additive | Usage and comments |
---|---|---|
Blood culture bottle | Sodium polyanethol sulfonate ( microorganisms |
Usually drawn first for minimal risk of contamination.[8] Two bottles are typically collected in one blood draw; one for aerobic organisms and one for anaerobic organisms.[9] |
Blue
("light blue") |
Sodium citrate
(weak calcium chelator/anticoagulant) |
Coagulation tests such as prothrombin time (PT) and partial thromboplastin time (PTT) and thrombin time (TT). Tube must be filled 100%. |
Plain red | No additive | Serum: cryoglobulins
|
Gold (sometimes red and grey "tiger top"[10]) | Clot activator and serum separating gel[11] | Serum-separating tube (SST): Tube inversions promote clotting. Most chemistry, endocrine and serology tests, including hepatitis and HIV. |
Orange | Clot activator and serum separating gel[12] | Rapid serum-separating tube (RST). |
Dark green | Sodium heparin (anticoagulant) | Chromosome testing, HLA typing, ammonia, lactate |
Light green | Lithium heparin (anticoagulant)
Plasma separator gel |
Plasma. Tube inversions prevent clotting |
Lavender ("purple") | EDTA (chelator / anticoagulant) | cyclosporin
|
Pink | K2 EDTA ( chelator / anticoagulant ) |
viral load |
Royal blue
("navy") |
EDTA ( chelator / anticoagulant ) |
Trace elements, heavy metals, most drug levels, toxicology |
Tan | Sodium EDTA ( chelator / anticoagulant ) |
Lead |
Gray |
Fluoride Oxalate
|
Glucose, lactate,[14] toxicology[15] |
Yellow | Acid-citrate-dextrose A (anticoagulant) | Tissue typing, DNA studies, HIV cultures |
Pearlescent ("white") | Separating gel and (K2)EDTA | toxoplasma and HHV-6
|
Black | Sodium Citrate | Paediatric ESR
|
QuantiFERON
Grey, Green, Yellow, Purple |
QuantiFERON
1. Grey (nil) tube 2. Green (TB1 antigen) tube 3. Yellow (TB2 antigen) tube 4. Purple (mitogen) tube |
Tuberculosis |