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Blood Transfusions

What Is a Blood Transfusion?

A blood transfusion is when a donor's blood is given to a patient. Blood transfusions save lives every day. Hospitals use them to help people who are injured, having surgery, getting cancer treatments, or being treated for other diseases that affect the blood, like sickle cell anemia.

What Is Blood Made of?

Blood is a mixture of cells and liquid, and each part has a specific job:

  • Red blood cells carry oxygen to the body's tissues and remove carbon dioxide. These cells are the ones that are most commonly transfused.
  • White blood cells help the body fight infection.
  • Platelets, the smallest blood cells, help blood to clot and control bleeding.
  • Plasma, the pale yellow liquid part of blood, is a mix of water, proteins, electrolytes, carbohydrates, cholesterol, hormones, and vitamins.
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Why Do People Need a Transfusion?

A child may need a blood transfusion if:

  • They lost blood during surgery or from an injury or an illness.
  • Their body doesn't make enough blood. Some illnesses and treatments can prevent the bone marrow from making blood (for example, chemotherapy lowers production of new blood cells).
  • They're at risk for problems from a blood or bleeding disorder, such as sickle cell disease, thalassemia, or anemia caused by kidney disease, hemophilia, or von Willebrand disease.

Where Does the Blood for a Transfusion Comes From?

Because there's no substitute for blood, the blood supply used for transfusion must be donated. Blood donation types include:

  • Autologous (ah-TOL-uh-gus) blood donation. This is when someone donates their own blood ahead of time for a planned surgery or other procedure. There is no age requirement, but in general, kids don't donate their blood for their own use until they're over age 12.
  • Directed donation. This is when a family member or friend with a compatible (good fit) blood type donates blood specifically for use by a patient in need of transfusion.
  • Volunteer donation. There's no medical proof that blood from directed donors is any safer than blood from volunteer donors. So most patients get blood donated through blood drives. These are often run by agencies like the American Red Cross. The minimum age for donating blood is 16 or 17 years old, depending on where a person lives.

How Should We Prepare for a Blood Transfusion?

If your child needs a blood transfusion, the doctor will describe the procedure. Ask questions if the explanation isn't clear. A parent or legal guardian will need to sign an informed consent form. This states that you understand the procedure and its risks, and give your permission for your child to have it.

If the situation is not a life-threatening emergency, two important tests are done before the transfusion: blood typing and cross-matching.

Blood Typing

To confirm your child's blood type, a nurse or technician draws a sample from a vein in your child's arm. (Except for the brief needle stick, this isn't painful and only takes a few minutes.) They immediately label the blood with your child's name, birth date, and medical record number, and make an armband with matching information for your child to wear. The blood goes to the hospital's blood bank lab, where technicians test it for blood type.

Blood from a donor needs to match the blood type of the person receiving it. There are 8 main blood types:

  1. O positive
  2. O negative
  3. A positive
  4. A negative
  5. B positive
  6. B negative
  7. AB positive
  8. AB negative

In emergencies, there are exceptions to the rule that the donor's blood type must match the recipient's exactly. O negative is the only blood type that people of all other blood types can receive. Medical teams use it in situations when patients need a transfusion but their blood type is unknown. Because of this, O negative donors are "universal donors." People who have type AB positive blood are "universal recipients" because they can safely receive any type of blood.


After blood typing is complete, a compatible donor blood is chosen. As a final check, a blood bank technologist will mix a small sample of your child's blood with a small sample of the donor blood to confirm they are compatible. Then the blood is labeled with your child's name, birth date, and medical record number and taken to where your child will get the transfusion.

What Happens During a Blood Transfusion?

In a transfusion:

  • The patient gets blood through a needle placed into a vein.
  • The needle is attached to thin plastic tubing that connects to a plastic bag containing the blood.
  • The patient's vital signs (temperature, blood pressure, and heart rate) are checked before, during, and after the transfusion.
  • A nurse watches for any signs of an allergic or other type of reaction, including rash, fever, headache, or swelling.

Transfusions usually take 1 to 4 hours, depending on how much blood is given and your child's blood type. You can stay with your child, who will be awake. Your child can sit comfortably in a reclining chair or lie down on a bed, watch a movie, listen to music, or play quietly, and might be able to eat and drink, walk around a bit, and use the bathroom.

If your child is going home after the transfusion, the technician will remove the plastic tube from the vein and place a bandage over the area. The site may be slightly sore or tingly for a little while. Your child might get medicine for any mild side effects, such as fever or headache.

Are There Any Risks to Blood Transfusions?

Some people worry about getting diseases from infected blood, but most countries have safety steps in place to prevent transfusing infected blood.

In the United States, all blood donors must give a detailed history, including recent travel, infections, medicines, and health problems. Also, the American Red Cross and other donation groups test donated blood for viruses like HIV (the virus that causes AIDS), hepatitis B, hepatitis C, syphilis, and West Nile virus. Because blood can also be infected with bacteria or parasites, some blood components also get tested for these. Blood that contains any of these things is destroyed.

Also, the needles and other equipment are sterile, and they're used only for one person and then thrown away in special containers.

If you have any questions about the risks of the transfusion, talk to anyone on the health care team.

What Are the Benefits of Blood Transfusions?

In kids with anemia or those getting chemotherapy, the greatest benefit of a transfusion is increased blood flow to nourish the organs and improve oxygen levels in the body. This can keep kids from feeling too tired and help give them enough energy for the activities of daily life. Benefits like this often are felt fairly quickly.

For someone with bleeding problems, transfusions with platelets or plasma can help to control or prevent bleeding complications.

Blood transfusions are common procedures and problems are rare. Talk with your child's doctor or health care team if you have concerns.