Health Library

Blood Transfusions

Why are blood transfusions performed?

There are several different components of the blood that can be transfused into an adult. Red blood cells are the most common type of blood product transfusion. If your health care provider has decided you might need a transfusion of blood, or blood products, he or she will explain the reasons for the transfusion. There are several reasons why you may require a blood transfusion, including the following:

  • A sudden loss of blood because of trauma  

  • An anticipated or actual loss of blood during surgery

  • A low hemoglobin before, during, or after surgery

  • Severe heart, lung, liver, or kidney disease

  • Bone marrow failure

  • Moderate to severe anemia

What is blood made of?

Human blood is made of a fluid called plasma that carries red and white blood cells and platelets. Each part of blood has special functions and can be separated from each other. The bone marrow is the soft, spongy material in the center of the bones that produces most of the body's blood cells.

What are red blood cells?

Red blood cells carry oxygen from the lungs to other body organs and carry carbon dioxide back to the lungs. A certain number of these cells are needed for the body to function. Bleeding due to trauma, surgery, or disease may cause a low red blood cell count.

What are white blood cells?

White blood cells fight infections by destroying bacteria, viruses, and other germs. White blood cells are rarely transfused. They are usually reserved as a temporary measure for people who have a low white cell count and severe infection that is not responsive to antibiotic therapy.

What are platelets?

Platelets help control bleeding by making clots in blood vessels opened by injury or surgery. The body may not be able to make enough platelets because of bone marrow disorders, increased destruction of platelets, or medications, such as chemotherapy. Platelets may be transfused before a procedure that may cause a person with a low platelet count to bleed.

What is plasma?

Plasma carries the blood cells throughout the body and contains proteins, vitamins, and minerals. Some of the proteins help the blood to clot. Plasma or fresh frozen plasma can be transfused in people who have a severe deficiency of certain clotting components of the blood.

Are blood transfusions safe?

The blood used at most hospitals is from volunteer donors. Donors are not paid for giving blood or blood products. Each blood donor must answer medical history questions and be given a limited physical examination before being accepted as a donor. The donated blood is carefully tested for hepatitis viruses B and C, HIV, human T-lymphotropic viruses (HTLV) I and II, syphilis, Chagas disease, and West Nile virus. These tests decrease the chances of transfusion-related infections.

How is blood transfused?

Blood is collected and stored in sterile bags. The bags are used once and then thrown away. Before blood is given to you, it is crossmatched with your own blood to make sure it is compatible. The blood will be given through a needle or catheter placed in the vein. Your temperature, blood pressure, and heart rate will be checked many times while the blood is being given. It may take a few hours to complete the process.

What is directed donation?

A directed (or designated) blood donation is one in which a person donates blood that is reserved (at the time of donation) for the transfusion of a specific patient at a later date. The donor is usually a family member or a close friend that has been chosen by the patient or the patient's family. Consult your health care provider if you are interested in learning more about directed donation. It is recommended that families donate in a particular person's name versus directed donation, because if directed blood is not needed, it is wasted. Blood must be donated within a month of the surgery. If not used, it will be released. An autologous donation is blood collected from the patient in advance of planned surgery.

Are directed donors safer than volunteer donors?

There is no proof that directed donors are safer than volunteer donors. Not all directed donor blood will be compatible with the patient's blood.

Are there risks in receiving a blood transfusion?

Most transfusions are performed without any problems. Mild side effects may include symptoms of an allergic reaction, such as headache, fever, itching, increased breathing effort, or rash. This type of reaction can usually be treated with medication, should you require additional transfusions. Serious side effects are rare and may include difficulty breathing, chest pain, and sudden drops in blood pressure. Transfusion reactions can occur even if the donated blood is the correct blood type. Transfusion with blood of the wrong type can be fatal, but this is unlikely to occur because blood is checked multiple times by medical personnel. 

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