A Vacutainer blood collection tube is a sterile glass or plastic tube with a
closure that is evacuated to create a vacuum inside the tube facilitating the
draw of a predetermined volume of liquid. Most commonly used to draw a
blood sample directly from the vein, these also are used to collect urine
samples. Vacutainer tubes may contain additives designed to stabilize and
preserve the specimen prior to analytical testing. Tubes are available
with or without a safety-engineered closure, with a variety of labeling
options and closure colors as well as a range of draw volumes.
Vacutainer tubes were invented by Joseph Kleiner and Becton Dickinson in 1949.
Vacutainer is a registered trademark of Becton Dickinson, which manufactures and
sells the tubes today. Principles
The vein is first punctured with the hypodermic needle which is carried in a
translucent plastic holder. The needle is double ended, the second shorter
needle being shrouded for safety by the holder. When a Vacutainer test tube is
pushed down into the holder, its rubber cap is pierced by the second needle and
the pressure difference between the blood volume and the vacuum in the tube
forces blood through the needle and into the tube. The filled tube is then
removed and another can be inserted and filled the same way. It is important to
remove the tube before withdrawing the needle, as there may still be some
suction left, causing pain upon withdrawal.
The test tubes are covered with a color-coded plastic cap. They often
include additives that mix with the blood when collected, and the colour of
the tube's plastic cap indicates which additives that tube contains.
The plastic caps are opaque for tubes with a normal vacuum. Translucent-topped
tubes contain a weaker vacuum in the same sized tube, and will obtain less
blood. The weaker suction makes them more suitable for smaller sized veins,
because the standardised suction of the tubes may cause the veins of elderly
people or those with delicate veins to collapse. In this case a syringe should
be used instead. Contents of tubes
The tubes may contain additional substances that preserve the blood for
processing in the medical laboratory. Using the wrong tube may therefore make
the blood sample unusable. These substances are typically a thin film
coating that is applied using an ultrasonic nozzle, a video of the
process can be seen here: Blood Collection Tube Coating Video.
The substances may include anticoagulants or a gel with
intermediate density between blood cells and blood plasma. Additionally, some
tubes contain substances that preserve certain chemicals or substances within
the blood, such as glucose. When the tube is centrifuged, the blood cells
sink to the bottom of the tube, are covered by a layer of the gel, and the
serum is left on top. The gel enables the tube to be tipped upside-down and
transported without the blood cells remixing with the serum. When a tube
that contains an anticoagulant is centrifuged, the clear liquid is plasma,
which contains the clotting factors. The meaning of the different colors are
standardized across manufacturers. The order of draw refers to the sequence
in which these tubes should be filled. The needle which pierces the tubes can
carry additives from one tube into the next, and so the sequence is
standardized so that any cross-contamination of additives will
not affect laboratory results. = Containers containing coagulants=
Gold or 'Tiger' Red/Black top: Clot activator and gel for serum separation
Red top PLASTIC tubes: Contains a clot activator and is used when serum is
needed Orange or Grey/Yellow 'Tiger' Top:
Contain Thrombin, a rapid clot activator, for STAT serum testing
= Containers containing anticoagulants= Green - Contains sodium heparin or
lithium heparin used for plasma determinations in clinical chemistry.
Sodium heparin collection tubes are the classically preferred tube for
peripheral blood or bone marrow for cytogenetic studies. Lithium heparin is
considered suboptimal for cytogenetics. Light Green or Green/Gray 'Tiger': For
plasma determinations. Purple or lavender - contains EDTA. This
is a strong anticoagulant and these tubes are usually used for complete
blood counts and blood films. Lavender top tubes are generally used when whole
blood is needed for analysis. Can also be used for some blood bank procedures
such as blood type and screen, but other blood bank procedures, such as
crossmatches must be in a pink tube in most facilities. EDTA tubes are
preferred by most molecular genetics laboratories for molecular genetic
studies. Grey - These tubes contain fluoride and
oxalate. Fluoride prevents enzymes in the blood from working, by preventing
the stage called glycolysis so a substrate such as glucose will not be
gradually used up during storage. Oxalate is an anticoagulant.
Light blue - Contain a measured amount of citrate. Citrate is a reversible
anticoagulant, and these tubes are used for coagulation assays. Because the
liquid citrate dilutes the blood, it is important the tube is full so the
dilution is properly accounted for. Dark Blue - Contains sodium heparin, an
anticoagulant. Also can contain EDTA as an additive or have no additive. These
tubes are used for trace metal analysis. Pink - Similar to purple tubes these are
used for blood banking. Black - Used for ESR also known as
Erythrocyte Sedimentation Rate or "sed rate." Goes to hematology department.
= Other= Red- Contains no additives. Tests for
antibodies and drugs often require these.
Light yellow - Contains sodium polyanethol sulfonate. Used for blood
culture specimens or acid-citrate-dextrose, used for blood
bank studies, HLA phenotyping, and paternity testing. ACD tubes can also be
used successfully for both molecular genetic studies and for culture for
cytogenetic studies, though few cytogenetics laboratories are aware of
this fact. Tan - Contains either sodium heparin or
K2EDTA. Used for lead determinations. These tubes are certified to contain no
lead. History and culture
= History= It was developed in 1947 by Joseph
Kleiner, and is currently marketed by Becton, Dickinson and company.
The plastic version, known as Vacutainer PLUS, was developed at Becton Dickinson
Research Center, RTP, NC in 1991-1993, by co-inventors E. Vogler, D. Montgomery
and G. Harper amongst others of the Surface Science Group as US patents
5344611, 5326535, 5320812, 5257633 and 5246666.
Vacutainer is now commonly used in phlebotomy and bloodletting process.
= Culture= The purple top tube became an issue in
the O.J. Simpson murder case when the defense alleged that small droplets of
blood found at the crime scene contained the preservative EDTA; had this been
true, it would have meant that the droplet might have been taken from the
purple top tube used to collect Simpson's blood and planted at the crime
scene. References
External links Animated Vacutainer Procedure with Order
of Draw Revisions to order of draw