How To Draw Blood: Step By Step Guide

blood donor

If you’re a nursing student or are studying to be a phlebotomist, you’ll need to be prepared to perform vital tasks, one of which is drawing blood. Phlebotomists are responsible for taking blood samples. But what if you’re a nurse and a sample needs to be taken right away, but the phlebotomist isn’t available? You need to know how to draw blood.

You may be surprised to learn that drawing blood, also called venipuncture, is not a standard procedure taught to nursing students. Why? Some hospitals deem it too risky to have nurses practice drawing blood. Because of this, they suggest that they go elsewhere to learn how to draw blood.

While it may not be part of your regular training, knowing how to safely draw blood can be crucial if a blood sample needs to be obtained quickly. A blood sample is required for most tests, which means it can be difficult to arrive at an accurate diagnosis without first drawing blood and testing it in the lab.

If you want to know how to draw blood, you can’t learn just by reading about it or watching demonstrations. It requires practical experience and training. Before you can practice drawing blood, it’s important to get a baseline understanding so that you’ll know what to expect. Follow safety procedures carefully, and you should have no trouble with this routine process. 

Finding The Vein

injecting arm

Before you can learn how to draw blood, you’ll need to learn how to find the vein. When drawing blood from an adult, try to identify the median cubital vein. This is a large vein that should be easy to draw from. It’s located between the bicep and forearm, also known as the cubital fossa. The median cubital vein is usually chosen because it poses little risk of damage to nerves or arteries.

In some patients, the median cubital vein may be visible just under the skin. However, each individual is different, and sometimes locating a vein can be more difficult. Nicotine can constrict veins, so if your patient is a smoker or any type of nicotine user, this might make the task more difficult.

Caffeine can also constrict veins, which is a common challenge when drawing blood early in the morning. Intravenous drug use causes veins to collapse, making many veins like the median cubital nonviable for drawing blood. In addition, some people have naturally smaller veins or mobile veins which roll instead of remaining stationary.

How To Draw Blood Safely

blood

If you want to know how to draw blood, you need to be prepared for everything which might present a challenge. Consult a map of the circulatory system if you need help. You might feel out of your depth if you’re inexperienced with drawing blood. If you don’t feel you can go on, then you should ask for a more experienced phlebotomist to step in.

Before you begin, check for any signs of scarring from previous needle punctures, hematomas, or blood clots. If for some reason you can’t draw a sample from the median cubital vein, you can opt instead for the basilic vein, but know that this means a higher risk of accidental injury to a nerve or artery. If you patient has just undergone a blood transfusion, a surgical procedure, or has an infected wound on one arm, draw blood from the opposite arm instead.  

Gathering The Supplies

medical kit

You might already have the supplies you need if you’ve got a medical kit handy. If not, you’ll gather the supplies you’ll need. This should be a simple matter if you have access to the medical supplies available in any hospital storeroom.

You’ll need disposable rubber gloves for your protection, biohazard bags which won’t leak, and a bag which won't puncture for you to dispose of sharp needles. These items are for your protection and safety. If, for any reason, you experience a leak or tear with any of the above items, stop the procedure immediately. Do not touch blood with your bare hands for any reason.  

You’ll need blood collection tubes, specimen labels, and the proper laboratory forms. The labels ensure that once the samples are drawn, they can be processed correctly by the lab tech staff. Without properly labeling your specimens they are likely to get lost among the hundreds of other samples, and a mislabeled specimen will cause confusion and might result in a misdiagnosis.

A tourniquet, gauze, and alcohol swabs will all be needed, as will adhesive bandages. It’s a good idea to have enough of these supplies to exceed the need, just in case you need more than you expected. Just be sure to return any clean, unused materials to the storeroom when you’re finished.

Finally, you’ll need needles and a device to transfer the blood into your collection tubes. Handle your needles carefully.  

Drawing The Blood

taking blood

If you haven’t sterilized them already before you start it’s a good time to wash your hands to ensure that you don’t accidentally facilitate the spread of infection. This crucial step can save lives and prevent undue suffering to patients who might otherwise be exposed to bacteria present in hospitals and other medical facilities. When you’re done, apply your latex gloves.

With your materials collected and your patient ready, consult your forms to confirm that the test has been ordered by a doctor. When you’re ready to begin, speak with the patient you’ll be drawing blood from. Remember that this procedure might be frightening for them even if it’s routine for you.

Ask questions about the patient’s medical history. Are they aware of any allergies they might have to latex? Are they currently taking blood-thinning medications? Do they have a family history of hemophilia that they know about? Get as much information as possible to avoid a complication or issue arising from drawing blood.

Getting Started

Once you’ve asked questions to reduce risk factors, tell the patient what you’ll be doing step by step as you go along. Make sure they’re informed of what you’re doing. This will help put them at ease and move the process along.

Instruct the patient to hyperextend their arm, then take the tourniquet and wrap it 3-4 inches above the cubital fossa if you plan to draw from the median cubital vein. You should wait no more than two minutes before beginning the blood draw. Ask the patient if they’re experiencing pain, numbness or tingling. Watch to make sure that the vein doesn’t change color.

So long as everything appears normal, and the patient isn’t feeling any unusual discomfort, you can proceed. The patient should make and hold a fist. It isn’t necessary to do this repeatedly. Holding a fist is sufficient. Tap the vein with your finger to dilate it, then take your alcohol swab and sterilize the area around the planned injection site.

Starting The Blood Draw

phlebotomist

With one hand, take your needle. Hold the patient’s arm below the injection site with your other hand. Hold the skin firmly to make sure that vein doesn’t move as you insert the needle through the skin and into the vein. This should be done at a 15- to a 30-degree angle.

If you’ve successfully punctured the vein, you’ll see blood appear in the catheter. Attach the collection tube and watch to make sure that blood begins flowing at a slow, even pace. When the collection tube has been filled, you can remove the tourniquet and withdraw the needle.

Quickly take your gauze and press down on the injection site. Wrap a bandage around the gauze to hold it in place. Take the used needle and place it carefully into your biohazard disposal receptacle. Remove your gloves and dispose of these as well. Be sure to label all your specimens carefully before depositing them in the lab.

Conclusion

Knowing how to draw blood is something that all sorts of medical professionals will be called upon to do at one point or another. If you’ve never done it before, the process can be intimidating. The important thing is to pay attention, follow all safety procedures to the letter, take it step by step and get as much practice as possible before attempting to draw blood from a patient on your own.

If possible, look for opportunities for hands-on training from in your area. Courses in venipuncture are available in nursing colleges and medical universities. Seek them out if venipuncture isn’t part of your regular coursework.

Prospective employers, especially those in intensive care wards, want to be assured that you know how to draw blood. So do your patients. The more practice you have, the better chance you’ll have of anticipating problems before they arise. Even if you’re diligently paying attention to every detail, the unexpected can still derail you.

Any phlebotomist will admit that drawing blood requires intuition as well as preparation. With experience, you’ll gain the confidence to proceed with a venipuncture procedure even if you have difficulty finding a vein in the patient’s arm. But until you’re prepared, it’s a good idea to practice with easier blood draws. Now you know how to draw blood practice, practice, practice.

Author: Emma Campbell

I am a director at the Phlebotomy Training Institute