Accurate laboratory results begin with appropriate specimen collection.
Most blood specimens are obtained using standard venipuncture technique.
Main Line Hospitals Laboratory Services supplies clients with
Vacutainer® brand collection tubes. Tube types are identified by stopper
color. In certain instances the use of Serum Separator Tubes (SST®) is
unacceptable. Prior to collection, consult the specific test ordered to
determine the proper tube type and specimen volume required.
Main Line Hospitals Laboratory Services provides the following standard
procedure for venous blood collection.
Venipuncture Procedure When Evacuated Tube System (Vacutainer®) Is Used
Thread the appropriate needle into the holder until it is
secure, using the needle sheath as a wrench.
Before using, tap all tubes that contain additives to ensure
that all the additive is dislodged from the stopper and the wall
of the tube.
Use a sterile blood collection tube. When drawing blood for
cultures, wipe the stopper with a suitable antiseptic solution.
Check the stopper to make certain it is dry before performing
Insert the blood collection tube into the holder and onto the
needle up to the recessed guideline on the needle holder. Avoid
pushing the tube beyond the guideline because a premature loss
of vacuum may result. The tube will retract slightly. Leave it
in this position.
Make sure the patient's arm or other venipuncture site is in a
downward position to prevent reflux.
Grasp the patient's arm firmly. The phlebotomist's thumb should
be used to draw the skin taut. This anchors the vein. The thumb
should be one or two inches (2.5 cm or 5.0 cm) below the
With the bevel up, line up the needle with the vein and puncture
the vein. Grasp the flange of the needle holder and push the
tube forward until the end of the needle punctures the stopper.
Blood can now be observed filling the tube. Maintain the tube
below the site when needle is in the vein.
Remove the tourniquet as soon as blood flow is established. Once
the draw has started, do not change the position of the tube
until it is withdrawn from the needle. During the procedure, do
not allow the contents of the tube to contact the stopper.
Movement of the fluid back and forth in the tube can cause
back-flow of blood into the venous system and possible adverse
Keep constant, slight forward pressure (in the direction of the
needle) on the end of the tube. This prevents release of the
shut-off sheath and stopping of blood flow. Do not vary pressure
or reintroduce pressure after completing the draw.
For tubes containing anticoagulant (i.e., light blue and
lavender top) fill the tube until the vacuum is exhausted and
blood flow ceases. This will ensure that there is a correct
ratio of anticoagulant to blood. It is normal for the tube not
to be completely filled.
When the blood flow ceases, remove the tube from the holder. The
shutoff sheath re-covers the point, stopping blood flow until
the next tube is inserted.
Mix immediately after drawing each tube that contains an
additive by gently inverting the tube five to 10 times. To avoid
hemolysis, do not mix vigorously.
To obtain additional specimens, insert next tube into holder and
repeat procedure from step nine.
Specimens for Therapeutic Drug Monitoring
Patient specimens for therapeutic drug monitoring or other toxicological
studies should not be collected in a Serum Separator or SST® tube. The
polymer used in this collection tube may bind with certain drugs. This
will result in falsely decreased patient results. Unless otherwise
specified in the Directory of Services, these specimens must be
collected in a standard non-gel blood collection tube (red top). Prior
to collection you should consult the specific test ordered to determine
the proper tube type and specimen volume required.
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