The Venipuncture From an Arm Vein

So You’re Going to Collect a Blood Specimen: An Introduction to Phlebotomy 21
The Venipuncture From an Arm Vein J
Venipuncture means the collection of blood from a vein. As a general rule, arm veins are the best
source from which to obtain blood. The preferred site is the antecubital fossa, which is where the
arm bends at the elbow. The vein of choice is the median cubital vein (see figure). The cephalic vein
is not preferred because it has a tendency to roll but can be used
as an alternative to the median cubital vein. The basilic vein
lies close to the brachial nerve and artery, and for this reason
should be avoided.
Brachial
In unusual situations, it may be necessary to use hand or wrist
veins when a suitable arm vein cannot be located, or if the arms
are bandaged or have been punctured repeatedly and are sore.
Veins from the underside of the wrist should not be used.
Sometimes, if the arm veins are used for repeated injection of
fluids, they may be thrombosed. Thrombosed means that clots
have formed and blood no longer flows. Thrombosed veins are
usually firm, discolored, and tender. If the arm veins are
thrombosed, you must use another site. Also, you should not
obtain blood from a vein that has a hematoma (bruise) from a
previous venipuncture.
Obtaining blood from a site other than the arm requires special
instruction. Notify your supervisor or follow your institution’s
procedures prior to obtaining
Arterial punctures
Do not attempt arterial
punctures unless you have
been properly trained and
competency has been
established. Always follow
your institution’s policies
and procedures.
blood from any site other than
the upper extremities. (See page
31 for information on collecting
blood from the arms of patients
who are receiving intravenous
fluids.)
Repeated phlebotomy may result in anemia, and the patient may
require a blood transfusion. Routine phlebotomy for 5 days usually
results in the loss of 100 mL of whole blood, which can lower the
hemoglobin by 0.48 to 1.02 g/dL and hematocrit by 1.3% to 2.5%. Conservation measures, such as the
use of pediatric-sized blood collection tubes, can reduce this phlebotomy-related cause of anemia.
Preparing the patient
Ensure that the patient does not have anything in their mouth prior to performing the venipuncture.
Position the patient so that:
z The vein you will use is readily accessible. Devices for locating veins are available (see Appendix 3).
z You are able to work in a comfortable position. If you are working from a cramped position or in
awkward quarters, your chance of performing a successful venipuncture will decrease.
z If the patient has a reaction, they will not fall.
Cephalic
Cephalic vein
vein
Median cubital Median vein
cubital
vein
Radial
Radial artery
artery
Brachial artery
artery
Basilic
Basilic vein
vein
Medial
Medial antebrachial vein
antebrachial
vein
Ulnar
Ulnar artery
artery

22 So You’re Going to Collect a Blood Specimen: An Introduction to Phlebotomy
Hospitalized patient not in bed
Have the patient sit at a small table where the elbow can
be placed on a hard surface, or in a position in which the
arm can be placed across the bed. If necessary, put a small
pillow or a roll of towels under the extended arm to
support it.
Outpatient/ambulatory patient
Ask the patient to sit in a chair designed for phlebotomy
or at a small table where the elbow is placed across a hard
surface. This will ensure that there is sufficient support
for the arm. This support will help prevent the patient
from pulling the arm back when the needle is inserted
into a vein. For infants or small children, have a second
individual, such as a parent, hold the arm of the child
firmly so that the arm will not jerk suddenly when the
needle is inserted into the vein.
Home visits
Tourniquet
Pillow
Follow the same principles outlined above. Do not place
your equipment on or near food. Ensure patient safety
since there may not be any help available if the patient
faints (see pages 36–37).
Some patients may have fragile bones
or restrictions to phlebotomy sites due
to recent surgeries. Make certain to
obey any signage that warns the
phlebotomist against potential injuries
to the patient from phlebotomy.
Hospitalized patient in bed
Make sure the patient is in a position
where the arm is easy to access for
venipuncture. Place the blood
collection tray where it is readily
available but is not in danger of being
upset by the patient. Never put your
equipment on the patient’s bed.
Never label tubes prior to collection.
Never leave any equipment in the
room.
Before phlebotomy, always ask
patients if they are taking
anticoagulants or if they have an
inherited blood clotting problem.
Patients who are taking medicine to
prevent their blood from clotting
(ie, anticoagulants such as coumadin,
heparin, or aspirin) or patients who
have inherited a blood clotting
abnormality (eg, hemophilia) may
continue to bleed from the punctured
vein. If this bleeding is not stopped,
blood may accumulate within the tissues
of the arm, specifically in the enclosed
area of the arm that surrounds the
muscle. This bleeding can lead to
compartment syndrome, a condition
in which the blood accumulates in a
contained space within the arm such
that the pressure produced can interfere
with blood flow and may injure the
muscle. This is a rare but very serious
complication and requires an
emergency surgical procedure to open
the compartment, relieve the pressure,
and stop the bleeding.

Never attempt venipuncture on
a standing patient. Patients
sometimes faint during or after
venipuncture. A standing patient
might suddenly collapse.
So You’re Going to Collect a Blood Specimen: An Introduction to Phlebotomy 23
Selecting the vein for venipuncture
Whenever possible, a blood specimen should not be obtained
from an extremity when an IV is running (see page 31) or when
dermatitis (skin inflammation) is present over the vein. If the
patient has had a mastectomy with lymph nodes removed from
the underarm area, a physician’s authorization is required prior
to performing phlebotomy on the involved extremity. The patient may offer specific information
about arm preference, and it is important for you to listen to their specific needs. Follow any special
instructions of the ordering physician or laboratory.
Inspect the preferred arm first. If it appears good, attempt to draw from this arm. You may be able
to see the vein. Veins appear blue and are slightly raised above the skin surface. Veins may be more
difficult to see in obese people.
Gloves can be put on at this point or they can be put on just before the venipuncture. Consult your
institution’s policy/procedure and follow the established guidelines. Always wash your hands or use
an alcohol-based hand rub before you glove, and wear new, properly fitting gloves. Never tear or
remove the tip of the finger of the glove for any reason.
Attach an unused sterile needle to the needle holder and assemble the necessary blood collection
tubes. Always have extra evacuated tubes close at hand in case problems are encountered with the
original tubes.
Apply the tourniquet about 3 inches above the elbow, or midway between the elbow and shoulder.
z The tourniquet must be applied with enough tension to compress the vein, but not the artery. (An
artery carries blood into the area, and if the tourniquet is too tight, blood flow will slow or stop.)
z If appropriate, have the patient form a fist to make the veins more prominent, thus aiding in
identification of the vein. There must not be any hand “pumping,” which can alter some analyte
concentrations. Asking the patient to clench their fist repeatedly has been reported to be a common
error in phlebotomy practice.
z Have the patient keep their hand closed until blood is flowing freely into the tube, and then ask the
patient to open their hand.
z Some special tests may require that blood be collected without a tourniquet. Consult your
phlebotomy manual or ask your supervisor for information.
z Do not leave the tourniquet on for more than 1 minute while you search for a vein. If more than
1 minute passes, release the tourniquet for at least 3 minutes. Then, reapply the tourniquet.
Inspect and palpate the area to find a vein. Prolonged obstruction of blood flow by the tourniquet
(ie, tourniquet in place for longer than 2 to 3 minutes) changes some test results.
Always palpate or feel for the vein, even when the vein is seen. This procedure gives you practice in
finding deeper, unseen veins. The vein will feel like an elastic tube that “gives” under the pressure of
your finger. Arteries pulsate, so make certain the structure you feel is not pulsating.