What Is a Blood Transfusion?

A blood transfusion is a safe, common procedure in which blood is given to you through an intravenous (IV) line in one of your blood vessels. Blood transfusions are done to replace blood lost during surgery or a serious injury. A transfusion also may be done if your body can't make blood properly because of an illness.

During a blood transfusion, a small needle is used to insert an IV line into one of your blood vessels. Through this line, you receive healthy blood. The procedure usually takes 1 to 4 hours, depending on how much blood you need.

Blood transfusions are very common. Each year, almost 5 million Americans need a blood transfusion. Most blood transfusions go well. Mild complications can occur. Very rarely, serious problems develop.

Important Information About Blood

The heart pumps blood through a network of arteries and veins throughout the body. Blood has many vital jobs. It carries oxygen and other nutrients to your body's organs and tissues. Having a healthy supply of blood is important to your overall health.

Blood is made up of various parts, including red blood cells, white blood cells, platelets (PLATE-lets), and plasma. Blood is transfused either as whole blood (with all its parts) or, more often, as individual parts.

Blood Types

Every person has one of the following blood types: A, B, AB, or O. Also, every person's blood is either Rh-positive or Rh-negative. So, if you have type A blood, it's either A positive or A negative.

The blood used in a transfusion must work with your blood type. If it doesn't, antibodies (proteins) in your blood attack the new blood and make you sick.

Type O blood is safe for almost everyone. About 40 percent the population has type O blood. People with this blood type are called universal donors. Type O blood is used for emergencies when there's no time to test a person's blood type.

People with type AB blood are called universal recipients. This means they can get any type of blood.

If you have Rh-positive blood, you can get Rh-positive or Rh-negative blood. But if you have Rh-negative blood, you should get only Rh-negative blood. Rh-negative blood is used for emergencies when there's no time to test a person's Rh type.

Blood Banks

Blood banks collect, test, and store blood. They carefully screen all donated blood for possible infectious agents, such as viruses that could make you sick. (See "What Are the Risks of a Blood Transfusion" for more information.)

Blood bank staff also screen each blood donation to find out whether it's A, B, AB, or O and whether it's Rh-positive or Rh-negative. Getting a blood type that doesn't work with your own blood type will make you very sick. That's why blood banks are very careful when they test the blood.

To prepare blood for a transfusion, some blood banks remove white blood cells. This process is called white cell or leukocyte (LU-ko-site) reduction. Although rare, some people are allergic to white blood cells in donated blood. Removing these cells makes allergic reactions less likely.

Not all transfusions use blood donated from a stranger. If you're going to have surgery, you may need a blood transfusion because of blood loss during the operation. If it's surgery that you're able to schedule months in advance, your doctor may ask whether you would like to use your own blood, rather than donated blood.

If you choose to use your own blood, you will need to have blood drawn a few times prior to the surgery. A blood bank will store your blood for your use.

Alternatives to Blood Transfusions

Researchers are trying to find ways to make blood. There is currently no man-made alternative to human blood. However, researchers have developed medicines that may help do the job of some blood parts.

For example, some patients with kidney problems can now take a medicine called erythropoietin that helps their bodies make more red blood cells. This means they may need fewer blood transfusions.

Surgeons try to reduce the amount of blood lost during surgery so that fewer patients need blood transfusions. Sometimes they can collect and reuse the blood for the patient.

Types of Blood Transfusions

Blood is transfused either as whole blood (with all its parts) or, more often, as individual parts. The type of blood transfusion you need depends on your situation.

For example, if you have an illness that stops your body from properly making a part of your blood, you may need only that part to treat the illness.

Red Blood Cell Transfusions

Red blood cells are the most commonly transfused part of the blood. These cells carry oxygen from the lungs to your body's organs and tissues. They also help your body get rid of carbon dioxide and other waste products. You may need a transfusion of red blood cells if you've lost blood due to an injury or surgery.

You also may need this type of transfusion if you have severe anemia (uh-NEE-me-eh) due to disease or blood loss. Anemia is a condition in which your blood has a lower than normal number of red blood cells, or the red blood cells don't have enough hemoglobin (HEE-muh-glow-bin). Hemoglobin—an iron-rich protein that gives blood its red color—carries oxygen from the lungs to the rest of the body.

Platelets and Clotting Factor Transfusions

Platelets and clotting factors help stop bleeding, including internal bleeding that you can't see. Some illnesses may cause your body to not make enough platelets or other clotting factors. You may need regular transfusions of these parts of your blood to stay healthy.

For example, if you have hemophilia (heem-o-FILL-ee-ah) A, you may need a special clotting factor to replace the clotting factor you're lacking. Hemophilia is a rare, inherited bleeding disorder in which your blood doesn't clot normally.

If you have hemophilia, you may bleed for a longer time than others after an injury or accident. You also may bleed internally, especially in the joints (knees, ankles, and elbows).

Plasma Transfusions

Plasma is the liquid part of your blood. It's mainly water, but also contains proteins, clotting factors, hormones, vitamins, cholesterol, sugar, sodium, potassium, calcium, and more.

If you have been badly burned or have liver failure or a severe infection, you may need a plasma transfusion.

Who Needs a Blood Transfusion?

Blood transfusions are very common. Each year, almost 5 million Americans need blood transfusions. This procedure is used for people of all ages.

Many people who have surgery need blood transfusions because they lose blood during the operation. For example, about one-third of all heart surgery patients have a transfusion.

Some people who have serious injuries—such as from car wrecks, war, or natural disasters—need blood transfusions to replace blood lost during the injury.

Some people need blood or parts of the blood because of illnesses. You may need a blood transfusion if you have:

• A severe infection or liver disease that stops your body from properly making blood or some parts of blood.
• An illness that causes anemia, such as kidney disease or cancer. Medicines or radiation used to treat a medical condition also can cause anemia. There are many different types of anemia, including aplastic, Fanconi, hemolytic, iron-deficiency, and sickle cell anemias and thalassemia (thal-a-SE-me-a).
• A bleeding disorder, such as hemophilia or thrombocytopenia (THROM-bo-si-to-PE-ne-a).

What To Expect Before a Blood Transfusion

Before a blood transfusion, a technician tests your blood to find out what blood type you have (that is, A, B, AB, or O and Rh positive or Rh negative). He or she pricks your finger with a needle to get a few drops of blood or draws blood from one of your veins.

The blood type used in your transfusion must work with your blood type. If it doesn't, antibodies (proteins) in your blood attack the new blood and make you sick.

Some patients have allergic reactions even when the blood given does work with their own blood type. To prevent this, your doctor may prescribe a medicine to stop allergic reactions. (See "What Are the Risks of a Blood Transfusion.")

If you have allergies or have had an allergic reaction during a past transfusion, your doctor will make every effort to make sure you're safe.

Most patients don't need to change their diet or activities before or after a blood transfusion. Your doctor will let you know whether you need to make any lifestyle changes prior to the procedure.

What To Expect During a Blood Transfusion

Blood transfusions take place in either a doctor's office or a hospital. Sometimes they're done at the patient's home, but this is less common.

A needle is used to insert an intravenous (IV) line into one of your blood vessels. Through this line, you receive healthy blood. The procedure usually takes 1 to 4 hours. The time depends on how much blood you need and what part of the blood you receive.

During the blood transfusion, a nurse carefully watches you, especially for the first 15 minutes. This is when reactions are most likely to occur. The nurse continues to watch you during the rest of the procedure as well.

What To Expect After a Blood Transfusion

After a blood transfusion, your vital signs are checked (such as your temperature, blood pressure, and heart rate). The intravenous line (IV) is taken out. You may have some bruising or soreness for a few days at the site where the IV was inserted.

You may need blood tests that show how your body is reacting to the transfusion.

Your doctor will let you know about signs and symptoms to watch for and report.

What Are the Risks of a Blood Transfusion?

Most blood transfusions go very smoothly. However, mild problems and, very rarely, serious problems can occur.

Allergic Reaction

Some people have allergic reactions to the blood given during transfusions. This can happen even when the blood given is the right blood type.

Allergic reactions can be mild or severe. Symptoms can include:

• Anxiety
• Chest and/or back pain
• Trouble breathing
• Fever, chills, flushing, and clammy skin
• A high pulse or low blood pressure
• Nausea (feeling sick to the stomach)

A transfusion is stopped at the first signs of an allergic reaction. The health care team determines how mild or severe the reaction is, what treatments are needed, and if the transfusion can safely be restarted.

Viruses and Infectious Diseases

Some infectious agents, such as HIV, can survive in blood and infect the person receiving the blood transfusion. To keep blood safe, blood banks carefully screen donated blood.

There is a risk of catching a virus from a blood transfusion, but it's very low.

• HIV. Your risk of getting HIV from a blood transfusion is lower than your risk of getting killed by lightning. Only about 1 in 2 million donations may carry HIV and transmit HIV if given to a patient.
• Hepatitis B and C. The risk of having a donation that carries hepatitis B is about 1 in 205,000. The risk for hepatitis C is 1 in 2 million. If you receive blood during a transfusion that contains hepatitis, you will likely develop the virus.
• Variant Creutzfeldt-Jakob disease (vCJD). Variant CJD is the human version of Mad Cow Disease. It's a very rare, yet fatal brain disorder. There is a possible risk of getting vCJD from a blood transfusion, although the risk is very low. Because of this, people who may have been exposed to vCJD aren't eligible blood donors. Go to the AABB Web site for more information about vCJD.

Fever

You may get a sudden fever during or within a day of your blood transfusion. This is usually your body's normal response to white blood cells in the donated blood. Over-the-counter fever medicine will usually treat the fever.

Some blood banks remove white blood cells from whole blood or different parts of the blood. This makes it less likely that you will have a reaction after the transfusion.

Iron Overload

Getting many blood transfusions can cause too much iron to build up in your blood (iron overload). People with a blood disorder like thalassemia, which requires multiple transfusions, are at risk of iron overload. Iron overload can damage your liver, heart, and other parts of your body.

If you have iron overload, you may need iron chelation therapy. For this therapy, medicine is given through an injection or as a pill to remove the extra iron from your body.

Lung Injury

Although it's unlikely, blood transfusions can damage your lungs, making it difficult to breathe. This usually occurs within about 6 hours of the procedure. Most patients recover. However, 5 to 25 percent of patients who develop lung injuries die from the injury. These people usually were very ill before the transfusion.

Doctors aren't completely sure why blood transfusions damage the lungs. Antibodies (proteins)—which are more likely to be found in the plasma of women who have been pregnant—may disrupt the normal way that lung cells work. Because of this risk, hospitals are starting to use men and women's plasma differently.

Acute Immune Hemolytic Reaction

Acute immune hemolytic reaction is very serious, but also very rare. It occurs if the blood type you get during a transfusion doesn't match or work with your blood type. Your body attacks the new red blood cells, which then produce substances that harm your kidneys.

The symptoms include chills, fever, nausea, pain in the chest or back, and dark urine. The doctor will stop the transfusion at the first sign of this reaction.

Delayed Hemolytic Reaction

This is a much slower version of acute immune hemolytic reaction. Your body destroys red blood cells so slowly that the problem can go unnoticed until your red blood cell level is very low.

Both the acute and delayed hemolytic reactions are most common in patients who have had a previous transfusion.

Graft-Versus-Host Disease

Graft-versus-host disease (GVHD) is when white blood cells in the new blood attack your tissues. GVHD is usually fatal. People who have weakened immune systems are the most likely to get GVHD.

Symptoms start within a month of the blood transfusion. They include fever, rash, and diarrhea. To protect against GVHD, patients with weakened immune systems should receive blood that has been treated so the white blood cells can't cause GVHD.

Key Points

• A blood transfusion is a safe procedure in which blood is given to you through an intravenous (IV) line in one of your blood vessels.
• Blood is transfused either as whole blood (with all its parts) or, more often, as individual parts. The individual parts include red blood cells, platelets, clotting factors, and plasma.
• Every person has one of the following blood types: A, B, AB, or O. Also, every person's blood is either Rh-positive or Rh-negative. The blood used in a transfusion must work with your blood type. If it doesn't, antibodies (proteins) in your blood attack the new blood and make you sick.
• Blood banks collect, test, and store blood. They carefully screen all donated blood so the right blood type is available for your transfusion.
• Each year, almost 5 million Americans need blood transfusions. This procedure is used for people of all ages.
• Many people who have surgery need blood transfusions because they lose blood during the operation. People who have serious injuries also may need blood transfusions to replace lost blood. Some people need blood transfusions because they have illnesses that prevent their bodies from properly making blood or parts of blood.
• Before a blood transfusion, a technician will test your blood to find out what blood type you have. Your doctor may prescribe medicine to prevent an allergic reaction. Most patients don't need to change their diets or activities before or after a blood transfusion.
• When there isn't time to test for blood type (such as during an emergency), type O blood is used. Type O is safe for almost everyone.
• Blood transfusions usually take place in either a doctor's office or a hospital. The transfusion takes 1 to 4 hours. The time depends on how much blood you need and what part of the blood you receive.
• After a blood transfusion, your vital signs are checked. You may need blood tests that show how your body is reacting to the transfusion.
• Most blood transfusions go smoothly. However, mild problems and, very rarely, serious problems can occur. They include allergic reactions, transmission of viruses and infectious diseases, fever, iron overload, lung injury, reactions from receiving the wrong blood type, and immune system problems.
• There is currently no man-made alternative to human blood. However, researchers have developed medicines that do the job of some blood parts. Research is ongoing to find a way to make blood.

Links to Other Information About Blood Transfusion

Non-NHLBI Resources

• Blood Donation and Transfusion (MedlinePlus)

Clinical Trials

• Current Research (ClinicalTrials.gov)