Every year, more than 4 million American kids and adults receive blood transfusions. In fact, blood transfusions help save lives each day!

So, what is a transfusion and why would someone need one?

What Is a Transfusion?

A blood transfusion (say: trans-few-zyun) is a way of giving one person's blood to someone else who needs it. When you need blood, you really need it because your body won't work right without enough healthy blood. Your heart pumps blood through blood vessels that reach every organ and tissue in the body. One of the blood's most important jobs is to deliver oxygen to each cell in the body. And without oxygen, the body can't stay alive.

Blood transfusions are possible because volunteers donate their blood. That makes it available at hospitals. It may sound creepy to donate blood, but it's safe and no big deal for a healthy person to donate a small amount — usually 1 pint (473 milliliters). Your mom or dad might have done this. Kids don't usually donate blood, but it's a good thing to do when you're older.

Healthy, donated blood is very valuable stuff. They even call the place that collects it the blood bank. Get it? A bank is a safe place for money and other valuables.

People who have certain illnesses such as hepatitis or HIV infection aren't allowed to donate blood, because they could pass their sickness on to another person through a blood transfusion. After blood is collected, blood banks test it very carefully to make sure the blood is free of diseases and germs. The blood bank discards any blood that could make someone sick.

Blood banks are also very careful not to contaminate stuff like needles. People who collect the blood are sure to use a new needle and fresh collection equipment for every donor. That way, even if someone's blood was infected, it can't be spread to other people or contaminate other healthy blood at the blood bank.

Why Are Transfusions Done?

Transfusions are often needed to save the lives of kids and adults who have life-threatening medical problems. A person might need blood if they've been in a bad accident, had surgery that caused blood loss, or have a certain disease, such as cancer or sickle cell anemia. Little babies that are born too early also might need transfusions to stay healthy while they grow.

In a transfusion, a person might get whole blood — meaning they receive blood just as it came out of the person who donated it. But usually someone needs only part of the blood. Blood has different parts, or components and each has a job to do:

• Plasma is a yellowish, watery liquid that holds red blood cells, white blood cells, and platelets.
• Red blood cells pick up oxygen in your lungs and then move to your heart so that oxygen is pumped all over your body.
• White blood cells fight off germs that could make your body sick.
• Platelets are cells that make your cuts stop bleeding. They stick together and plug up the cut blood vessel so that no more blood will flow out.

Red blood cells, plasma, and platelets are commonly used in transfusions. Red blood cells help people who have lost a lot of blood or are anemic. Doctors and nurses give people plasma if they are bleeding too much, and platelets help people with certain types of cancers or bleeding problems.

Not Just Any Blood Will Do

Hospitals have to be careful when they give a blood transfusion. People have different blood types — and not all blood will work in all people. Do you know your blood type? Your mom or dad might. You may have heard of the most common system for labeling blood types: type A, B, AB and O. This is called the ABO system for typing blood.

But don't worry if no one knows. If you ever need blood, the hospital would very quickly find out your blood type and may even do additional tests to make sure you get the right kind of blood. The blood will be tested against your blood before it is given to make sure it is compatible with your blood. This test is called cross matching.

What Happens During a Transfusion?

Before a person gets blood, they need to give a little. Why? So the blood sample can be tested to determine your blood type and the best match from the blood bank. To get the sample, an IV — or intravenous (say: in-truh-vee-nus) — catheter (a tiny straw-like tube that goes into the vein) will be inserted into a vein in the person's hand or arm. It will feel like a small pinch, but only when it first goes in. The blood will be drawn through this catheter, which is attached to a syringe.

The IV will be taped carefully in place so that it can be used to give the blood when it is ready. A nurse will bring in a bag of the blood that has been specially selected for the person. The bag will hang on a pole near the hospital bed and a tube will be inserted into the bag. The bag of blood is usually warmed before going into the person's body. Then the blood can travel from the bag, through the IV, and into the person's blood vessels.

Most of the time, the person doesn't feel any discomfort when the blood goes in. During the transfusion, nurses and others will make sure the person feels OK. A nurse keeps an eye on the person's temperature and blood pressure. The nurse also looks to make sure there's no rash or other signs of an allergic reaction.

Transfusions can be done very quickly, if necessary, like in an emergency situation. But when it's not an emergency, the transfusion can happen more slowly, taking a few hours to finish. When the transfusion's done, the person has taken a big step toward being healthy and feeling good again.

Reviewed by: Yamini Durani, MD
Date reviewed: January 2012