Tips on Blood Testing

Collecting Blood for Testing

How It’s Done

The blood needed for a diagnostic test is usually fairly easy to obtain via a procedure called venipuncture, a term which means, quite simply, “puncturing the vein.” The person performing this procedure is called a phlebotomist.

Phlebotomists who work in hospitals, cancer clinics, and outpatient settings perform numerous venipunctures each day, experience that quickly makes them good at handling difficult situations and distressed individuals. The phlebotomist knows how to put patients at ease, knows how to assist someone who is feeling lightheaded or faint, and has received training specific to the anatomy and needs of children and the elderly.

Knowing that the person collecting the sample has undergone thorough training and demonstrated a high level of competency can help a nervous patient relax.

What Will Happen?
During venipuncture, the phlebotomist inserts a needle through your skin into a vein. The amount of blood needed for the test is withdrawn through the needle into a special tube or tubes. The tubes are sent to a laboratory, where the blood is analyzed as the health care practitioner has ordered. Most often, the phlebotomist is able to identify a vein in the crook of your elbow that will be easily accessible and then applies a tourniquet above the site to make the vein more apparent. (The elbow area does not have many nerves so this is a good site; the wrist, hand and foot are other sites that can be used.) Making a fist when you are asked to helps make the vein more prominent. The procedure usually takes less than 3 minutes. Afterward, the patient is usually asked to apply gentle pressure over a clean dressing to help the blood clot and prevent swelling and a hematoma (a black and blue mark where blood has pooled).

Will It Hurt?
When the needle is inserted under the skin, you might feel a slight sting, and there may be additional discomfort when it is withdrawn. If you are accompanying a child or an anxious patient, it helps to explain that he or she will feel momentary pain or discomfort. Don’t say, “This won’t hurt a bit,” because the patient will then have reason to mistrust the people and situation when it does sting. Be honest, create a reasonable expectation, and you will really help the patient.

Not Flowing Well?
Being well-hydrated helps blood flow better and makes the veins more likely to raise up and be found easily, so make sure you drink plenty of fluids a day or two before your test. But, also remember to follow your health care provider’s instructions—some tests require that you not drink certain liquids prior to the test. You may also want to take a walk while waiting, or on your way to the test, which raises blood pressure and can make veins more prominent (routinely doing hand and arm exercises also helps those requiring frequent testing). Even eating well the day before, if fasting is not required, improves blood flow.

Dry Skin?
Applying a moisturizer at least 4 times a day from the hand to the elbow (or wherever you expect the skin will be punctured) can make the puncture less painful. Lotions work best when applied just after the skin has been wet, for example after bathing, showering, swimming, or washing dishes.

Cold Hands?
Being warm increases your blood circulation, which makes it easier for the phlebotomist to find a vein. While you are waiting, you may want to leave your coat or sweater on and let your arm dangle down to increase the blood pressure in the veins. If your blood is difficult to draw, lying down and warming your hands under a heating pad and blanket usually provide good results.

Getting Anxious?
Talk about or recall something pleasant while you wait to take your mind off your anxiety; you can also bring reading or music.

Don’t Like the Sight of Blood?
Looking away while the needle is being inserted or as the blood flows into the tube may help keep you from becoming anxious.

Feeling Faint?
If you are nervous or have a tendency to feel woozy or faint, tell the phlebotomist before you begin. Your blood can be drawn while you are lying down, which will help you avoid fainting and injuring yourself. If, at any time, you feel faint or lightheaded, tell the phlebotomist or someone nearby. Putting your head between your knees or lying down should make you feel better soon.

Can’t You Find the Vein?
If the phlebotomist “sticks” a patient twice with the needle but does not succeed in reaching the vein, another phlebotomist may step in to complete the procedure. This keeps both the patient and the technician from becoming flustered and should be seen as a reassuring step. Even after one unsuccessful attempt, if you feel unsure about the phlebotomist, it is okay to ask for someone else to handle the second.

What Helps Afterward?
If you experience swelling, bruising, or pain, follow general first-aid procedures to relieve the pain, including icing the site, using the affected arm as little as possible, and taking a pain reliever if that is an allowable medication for you.

When Blood is Hard to Draw

Most people may be pleasantly surprised that a blood draw is quick, easy, and relatively painless. While they may have some anxiety ahead of time, they may find that it was faster, less painful and easier than expected.

Some people, though, have veins that are quite small and difficult to access. Some veins are scarred from repeated punctures to the vein or blocked. People undergoing chemotherapy, for example, and those being monitored for side effects while taking warfarin (COUMADIN®) may have more difficulty during a blood draw because their veins have been punctured so often. For these individuals, venipuncture can involve more than one needle stick.

Experienced patients are likely to take a more assertive role in the procedure, telling the technician the good spots to try or the needles, techniques, or instruments that work well. Women who have had a mastectomy, for example, are likely to tell the phlebotomist which arm to use to avoid the lymph nodes more prone to infection. Some people who know their blood is difficult to draw always request the technician with whom they have had the best results. If you are frustrated by a lack of quick success, try to stay open to the phlebotomist’s suggestions so together you can create a protocol that works well for you.

In addition to the tips above, here are some more suggestions from the book Caregiving, which discusses the vein problems cancer patients can have during and after treatment:

Numbing Creams — Ask about products that numb the skin, such as EMLA cream.
Fingerstick Tests — Ask if a fingerstick test is available.
Catheters and Ports — If you know you need frequent blood draws over a period of time and your blood draws are requiring three or more attempts before they are successful, ask about the availability and advisability of using ports or catheters.

Other Methods for Collecting Blood

Fingersticks and Heelsticks

A small number of blood tests require just a fingerstick. A very small sample of blood from your capillaries can be obtained from the fingertip or earlobe, or from the heel of a newborn (heelstick). Warming the skin with moist compresses for about 10 minutes facilitates blood flow to the area. The skin is then pricked with a lancet. Because there are more nerves in the finger than in your elbow, you may find that a fingerstick is a bit more painful than venipuncture, although less intimidating.

Arterial Samples

In more critical situations—usually not outpatient diagnostic tests—the blood from a patient’s arteries needs to be analyzed. This procedure, known as an arterial sample, is performed by a health care practitioner such as a specially trained nurse. A local anesthetic may be administered and, afterward, the nurse will apply pressure to stop the bleeding and prevent a hematoma.