CLINICAL LAB SCIENEC

CHAPTER 11: PHLEBOTOMY 271
veins and a flash of blood will be seen as soon as the needle enters
the vein, as occurs with the use of a syringe.
Choosing the correct tube(s) will be critical, as there are a large
variety of specialized tubes used in collecting blood. Some tubes contain
an anticoagulant and are used to obtain the liquid portion of the
blood (plasma), which is commonly used for coagulation tests and
some chemistry tests. Other types of tubes without anticoagulant are
designed for obtaining serum. Serum is also a liquid component of
blood and is derived when the blood collected in the tube is allowed
to clot. The tube is then centrifuged to separate the cells of the blood
from the liquid portion of the blood. Some types of tubes used to
obtain serum contain a barrier device that separates the liquid portion
of the blood from the cells or solid components.
Patient Position and Order of Draw
Safety Alert
Causes of Injuries to Patient and
Phlebotomist
• Phlebotomist sticks himself or herself
with a used needle.
• Phlebotomist or laboratory worker
leaves used needles and lancets in the
bed linen.
• Tube of blood is dropped and broken
(more common when glass tubes were
used).
• Patient side rails are left down, and
patient falls from the bed.
• Patient is combative and injures
The result of a number of laboratory procedures may be skewed himself or the phlebotomist.
due to the anatomic position assumed by the patient. Results may
be altered if the patient is standing, sitting, or lying down, or if
the tourniquet is on the arm for more than a half-minute to a minute. Among
the many tests that are affected considerably by having a tourniquet on the arm
for an extended period, cholesterol determinations and hemoglobin levels are
possibly affected the most.
Order of draw refers to the sequence of tubes used in drawing blood. The
specific order in which the tubes are used serves to avoid contamination by preventing
carryover from tubes containing chemicals, which might result in inaccurate
test results. There are several major types of blood collection tubes that
have been developed for specific purposes and the color of their tube stoppers
may vary by manufacturer. Some tubes are designed to provide preservation of
the sample. Others are sterile and are used for determining the presence of bacteria.
Several types of tubes allow the blood to clot and serum to be obtained when
spun at a high rate of speed in a centrifuge. Some tubes contain a barrier substance
that separates liquid and solid portions of blood upon centrifugation, and
some of these may include a clot enhancer to speed the clotting process. Several
types of anticoagulants are found in some specially designed tubes to preserve the
morphology of blood cells or to provide plasma for coagulation studies.
Performance of Venipuncture
As mentioned previously, phlebotomists are most often responsible for collecting
blood samples, particularly in the larger hospitals. Training for phlebotomists
includes skills other than the actual process of obtaining blood through
venipuncture. Sample transport and separation and logging the sample into the
LIS are among the duties of the phlebotomist. The phlebotomist must also have
strong skills in dealing with people, such as ill patients and their families and
other health care professionals. The following steps take into account the use of
many of the attributes the phlebotomist should possess.
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