Accessible Search Form           Advanced Search


National Heart Lung and Blood Institute Logo

For more information, visit http://www.nhlbi.nih.gov/health/health-topics/topics/bt/


What Is a Blood Transfusion?

A blood transfusion is a safe, common procedure in which you receive blood through an intravenous (IV) line inserted into one of your blood vessels.

Blood transfusions are used to replace blood lost during surgery or a serious injury. A transfusion also might 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 in the body. Blood has many vital jobs. For example, it carries oxygen and other nutrients to your body's organs and tissues. Having a healthy supply of blood is important for 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 of the population has type O blood. People who have 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 who have 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 only get 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 infectious agents (such as viruses) or other factors that could make you sick. (For more information, go to "What Are the Risks of a Blood Transfusion?")

Blood banks also screen each blood donation to find out whether it's type A, B, AB, or O and whether it's Rh-positive or Rh-negative. You can get very sick if you receive a blood type that doesn't work with your own blood type. Thus, blood banks carefully test donated 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 one or more 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. Currently, no man-made alternative to human blood exists. However, researchers have developed medicines that may help do the job of some blood parts.

For example, some people who have kidney problems take a medicine called erythropoietin. This medicine helps their bodies make more red blood cells. As a result, 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 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. Red blood cells 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 surgery or an injury. You also may need this type of transfusion if you have severe anemia (uh-NEE-me-uh) due to a disease or blood loss.

Anemia is a condition in which your blood has a lower than normal number of red blood cells. Anemia also can occur if your red blood cells don't have enough hemoglobin (HEE-muh-glow-bin).

Hemoglobin is an iron-rich protein that gives blood its red color. This protein carries oxygen from the lungs to the rest of the body.

Platelet and Clotting Factor Transfusions

Platelets and clotting factors help stop bleeding, including internal bleeding that you can't see. Some illnesses can prevent your body from making enough platelets or clotting factors. If you have one of these illnesses, you might need regular platelet or clotting factor transfusions to stay healthy.

For example, if you have hemophilia (heem-o-FILL-ee-ah), you may need a special clotting factor to replace the clotting factor you're lacking. Hemophilia is a rare, inherited bleeding disorder in which the 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 it 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. The procedure is used for people of all ages.

Some people who have surgery need blood transfusions because they lose blood during their operations. People who have serious injuries—for example, from car crashes, war, or natural disasters—also may need blood transfusions to replace blood lost during the injury.

Some people need blood or blood parts because of illnesses. For example, blood transfusions might be used to treat:

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



What To Expect Before a Blood Transfusion

Before a blood transfusion, a technician tests your blood to find out your blood type (A, B, AB, or O) and whether you're 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 for 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 people have allergic reactions even when the donated blood does work with their own blood type. To prevent this, your doctor may prescribe a medicine to stop allergic reactions. (For more information, go to "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 people don't need to change their diets 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 a person's home, but this is less common. Blood transfusions also are done during surgery and in emergency rooms.

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 allergic 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 (IV) line is removed from your blood vessel. You may have some bruising or soreness for a few days at the site where the IV was inserted.

You may need blood tests to 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. Sometimes mild problems can occur. Very rarely, serious problems occur.

Allergic Reactions

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

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

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

A nurse or doctor will stop the transfusion at the first signs of an allergic reaction. The health care team will figure out the severity of the reaction, what treatments are needed, and whether they can safely restart the transfusion.

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.

The risk of catching a virus from a blood transfusion is low.

  • HIV. All donated blood is tested for HIV. Also, other measures are used to screen possible donors. For example, donors are questioned about whether they have any signs and symptoms of HIV or HIV risk factors. Only about 1 in 2 million donations might 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 200,000 to 1 in 360,000. The risk of hepatitis C is 1 in 1 million to 1 in 2 million. If you receive blood during a transfusion that contains hepatitis, you'll likely develop the virus.
  • Variant Creutzfeldt-Jakob disease (vCJD). This disease 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.

Fever

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

Some blood banks remove white blood cells from whole blood or different parts of the blood. This reduces the risk 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 who have a blood disorder like thalassemia, which requires multiple transfusions, are at risk for 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 (ke-LAY-shun) 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 hard to breathe. This usually occurs within about 6 hours of the procedure.

Most patients recover. However, some patients who develop lung injuries die. These people usually were very ill before the transfusion.

Doctors aren't completely sure why blood transfusions damage the lungs. Antibodies (proteins) that 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's and women's plasma differently.

Acute Immune Hemolytic Reaction

An 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. Your doctor will stop the transfusion at the first sign of this reaction.

Delayed Hemolytic Reaction

This is a much slower version of an 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.

Delayed hemolytic reactions are more common in patients who have had a previous transfusion than in those who haven't.

Graft-Versus-Host Disease

Graft-versus-host disease (GVHD) is a condition in which white blood cells in the new blood attack your tissues. GVHD usually is fatal. This condition affects people who have very weak immune systems.

Symptoms start within a month of the blood transfusion. They include fever, rash, and diarrhea. To protect against GVHD, donated blood can be treated so that the white blood cells can't cause GVHD.




Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. For example, this research has helped evaluate treatments and therapies for many diseases and conditions.

The NHLBI continues to support research on various treatments, including blood transfusions. For example, the NHLBI is involved in research to explore:

  • How well white blood cell transfusions treat infections in people who have neutropenia (a white blood cell disorder), and how safe the transfusions are
  • Whether the length of time that red blood cells are stored before transfusion affects clinical outcomes in patients having complex heart surgery
  • Two approaches to red blood cell transfusions in patients who have anemia and coronary heart disease
  • Ways to improve blood transfusion processes and safety

Much of this research depends on the willingness of volunteers to take part in clinical trials. Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions.

For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you may gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to blood transfusions, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.




Links to Other Information About Blood Transfusions

NHLBI Resources

Non-NHLBI Resources

Clinical Trials

 
January 30, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.

Twitter iconTwitter         Facebook iconFacebook         YouTube iconYouTube        Google+ iconGoogle+