Selecting the vein for venipuncture
Whenever possible, a blood specimen should not be obtained from an extremity when an IV is
running (see page 29) 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
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.
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, and have the patient make a fist.
❖ 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
❖ Have the patient form a fist, which makes the veins more prominent, thus aiding in
identification of the vein. There must not be any hand “pumping,” which can alter some
❖ Have the patient keep their hand clenched until blood is flowing freely into the tube, and
then ask the patient to unclench their hand.
❖ Some special tests may require that blood be collected without a tourniquet. Consult your
phlebotomy manual or ask your supervisor for information.
❖ 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, re-apply 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
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
20 So You’re Going To Collect A Blood Specimen
If the vein has been used repeatedly for fluid injections and punctures, it may feel cord-like.
Such a vein should not be used because it is difficult to obtain blood from it.
If a vein is difficult to find, it may become easier to see after massaging the arm from wrist to
elbow, which forces blood into the vein. Or, the area may be tapped sharply with the index and
second finger 2 or 3 times, which may cause the vein to dilate. If necessary, a warm damp
washcloth can be placed on the skin for a few minutes to make the veins stand out.
❖ If you are not certain that you have found a vein, examine the other arm. Sometimes veins
in one arm are small, while those in the other arm are larger.
❖ A patient who has had prior venipunctures may be able to tell you where a vein can best
❖ A transilluminator or pocket pen light may be used to help visualize the vein in infants
Performing the venipuncture
❖ Starting from the point you have selected
for the venipuncture and moving outward
in a circular motion, clean the area for
venipuncture with an alcohol or
chlorhexidine gluconate/alcohol pad, as
appropriate. If you accidentally touch the
skin where you plan to draw blood, re-clean
the area with alcohol. Allow the area to dry,
or wipe dry in an outward circular motion
SMITH JOHN J
with a gauze pad to prevent pain and
hemolysis (the destruction of red blood cells)
due to residual alcohol. Do not blow on the
area as this will contaminate the site.
❖ The vein should be “fixed,” or held
taut, during the puncture. To do this,
place your thumb about an inch
below where the needle is to enter
and press down on the arm; at the
same time, pull the skin toward the
hand. The fingers of your hand
SMITH JOHN J
should be around and underneath
the patient’s arm, grasping the
patient’s arm as your thumb stretches
and holds the vein taut.
An Introduction To Phlebotomy 21
❖ The needle should be in line Needle
with the vein.
❖ The needle should be at
about a 15-degree angle
with the skin (see figure). Rubber Septum Evacuated tube
❖ After removing the
protective cap, look at the
needle to make sure it is free
of burrs and nicks. Properly
discard any suspicious needle and blood tube holder into an approved puncture-resistant
❖ Insert the first tube into the evacuated tube holder resting on the inside needle. Do not push
all the way down since this will prematurely break the vacuum seal of the tube. Under certain
circumstances you may wish to use a syringe with a needle or a butterfly device (winged set)
rather than an evacuated tube collection system.
❖ Inform the patient that the venipuncture
is about to occur.
Needle bevel up ❖ Introduce the needle with the bevel up.
(The bevel is the flattened area that
extends back from the tip.)
❖ The skin should be punctured with a
clean, smooth motion. Do not hesitate.
❖ When you introduce the needle, grip the holder firmly and keep it steady.
❖ As the needle enters the vein, a little “give” will be noted.
❖ After the vein is entered, decrease the angle of the needle and slide the needle further into
❖ When the needle is in the vein, push the
collection tube all the way down into the
blood tube holder, keeping the needle as
stable as possible in the vein. Blood Vein Evacuated
should flow into the tube due to the Tube
vacuum in the tube.
❖ As blood flows into the collection tube
following the puncture, watch the flow
until collection is completed and the tube Skin
has been filled.
❖ As soon as the tube is filled, hold the blood tube holder steady and carefully pull the tube
out without dislodging the needle from the vein. If the tube contains an additive, mix the
contents by gently inverting it 5 to 10 times before the next tube is inserted into the blood
tube holder. There are important exceptions to this rule: light blue top sodium citrate tubes
22 So You’re Going To Collect A Blood Specimen
should be inverted no more than 3 to 4 times;
pearl white top EDTA tubes should be mixed
8 to 10 times.
❖ If additional tubes are required, slide the next
tube in and press the tube firmly so that the
stopper is fully penetrated by the needle.
❖ Remove the last collection tube from the holder
before removing the needle from the vein.
❖ If blood collection will require several minutes,
SMITH *PREC R
JOHN AUT 7CC
the tourniquet should be removed as soon as
there is good blood flow into the tube. Optimal
recommended total tourniquet time, including prepuncture search, should not exceed
❖ The tourniquet must be removed before withdrawing the needle from the puncture site.
❖ After removing the needle from the puncture site, immediately activate or deploy the safety
device and discard the needle and blood tube holder into an approved puncture-resistant
You have collected the blood specimen ... what next?
After collecting the specimen, place a dry, clean gauze pad or cotton ball over the needle
puncture site and apply pressure. Instruct the patient to keep the arm in an extended straight
position, and press the gauze pad or cotton ball
Common errors against the puncture site for at least 5 minutes.
The most common errors a beginner Instruct the patient on how to maintain
makes are failure to fix the vein or failure pressure on the puncture site. If the patient
to insert the needle tip all the way within cannot apply pressure to the gauze pad on the
the vein. If the needle tip is only partly arm, you should press it on the arm as long as
through the vein, blood flow will be necessary to stop the bleeding (2 to 5 minutes).
inadequate. Never use an alcohol pad to maintain pressure
and stop the bleeding.
After the needle has been removed from
the arm, some phlebotomists instruct the Finally, inspect the puncture wound. When
patient to bend the arm, but this is wrong. the bleeding has stopped, apply an adhesive
This practice keeps the needle puncture bandage. Instruct the patient to leave it in
wound open, permitting blood to escape place for at least 15 minutes.
freely into the tissues, causing a bruise or
Label the collection tubes in the presence
hematoma. The proper procedure is to
of the patient. Information that should be
have the patient apply pressure to the site
recorded on the tube includes the patient’s full
with a clean gauze pad. An alcohol pad
name, unique identification number, date and
should not be used to apply pressure.
time collected, and your initials.
An Introduction To Phlebotomy 23
❖ If the patient has a low platelet count, a bleeding disorder, or is on anticoagulation therapy,
the blood flow may not stop readily. This continued flow may be related to the patient’s
disease or therapy. In these cases, have the patient elevate the arm above shoulder level and
keep the pressure on the site for 5 to 10 minutes or more. When bleeding has definitely
stopped, apply a pressure adhesive bandage (folded gauze pad firmly held in place by
appropriate tape). Inform the patient not to use the affected extremity for a short period of
time and avoid strenuous activity using the extremity for 24 hours.
❖ If the bleeding continues, maintain pressure on the phlebotomy site and ask the nurse or
your supervisor for help. Do not leave the patient until the situation is under control.
An accidental arterial puncture will result in the
Before phlebotomy, always ask patients if they pulsating flow of bright red blood, which will
are taking anticoagulants or if they have an not stop readily. Immediately withdraw the
inherited blood clotting problem. Patients who needle, apply pressure until the bleeding has
are taking medicine to prevent their blood from stopped. When bleeding has stopped, apply a
clotting (ie, anticoagulants such as coumadin, pressure adhesive bandage. Notify the nurse or
heparin, or aspirin) or patients who have physician that an accidental arterial puncture
inherited a blood clotting abnormality has occurred. If the bleeding continues,
(eg, hemophilia) may continue to bleed from the maintain pressure on the phlebotomy site and
punctured vein. If this bleeding is not stopped, ask the nurse or your supervisor for help. Do
blood may accumulate within the tissues of the not leave the patient until the situation is under
arm, specifically in the enclosed area of the arm control.
that surrounds the muscle. This bleeding can lead
to a condition called “compartment syndrome” Do not leave any of your blood collection
where the blood accumulates in a contained space materials at the collection site, such as in the
within the arm such that the pressure produced patient’s room or home.
can interfere with blood flow and pressure may
injure the muscle. This is a rare but very serious Remove and properly dispose of your gloves,
complication and requires an emergency surgical and wash your hands with either an alcohol-
procedure to open the compartment, relieve the based hand rub (if hands are not visibly
pressure, and stop the bleeding. soiled) or soap and water (if hands are visibly
soiled), before proceeding to the next patient.
Multiple specimen collection ✪
In general, when multiple tubes are drawn during a single venipuncture, tubes without additives
should be drawn before tubes with additives to avoid contamination. Common additive tubes
are also drawn in a specific order to avoid potential additive cross-contamination (see chart on
Hemolysis, the destruction of red blood cells, should be avoided to ensure accurate results.
Avoid hemolysis by allowing the venipuncture site to dry thoroughly after cleaning. Avoid
prolonged use of a tourniquet or repeated fist clenching. Avoid using a needle that is too large
24 So You’re Going To Collect A Blood Specimen
or too small (consult institutional policy), and avoid drawing blood from a site that has a
Hemolysis may be caused by slow blood flow into the tube due to a suboptimal venipuncture.
If using a syringe, make sure the needle is fitted securely on the syringe to avoid frothing.
Gently invert filled tubes (as directed by the manufacturer) rather than shaking the tubes, as
shaking may cause hemolysis.
If blood fails to enter the evacuated tube
If the needle was not introduced far enough into the
vein, lower the angle and advance it a little more.
If the needle appears to have missed the vein, make
sure the vein is fixed with the thumb, partially pull
the needle back without removing it from the skin,
and attempt to puncture the vein again.
Positioning of the needle is critical. If you think that
you have gone completely through the vein, slowly
pull back the needle. As the needle moves back into
the center of the vein, blood will flow. Be careful
not to pull the needle back further once flow is
Other needle positioning errors include:
❖ Bevel against the wall of the vein, restricting blood flow into the needle.
❖ Partially inserted in the wall of the vein, allowing blood to leak into surrounding tissue.
❖ Collapsed vein.
❖ Thrombosed vein.
If at any time during the above maneuvers a hematoma appears, have the patient unclench their
fist, release the tourniquet immediately, withdraw the needle, and apply pressure with a clean,
gauze pad for at least 5 minutes (see page 23). Ensure that further bleeding has stopped, or
continue to maintain direct pressure. If significant bleeding occurs, notify the supervisor, nurse,
An Introduction To Phlebotomy 25