Blood component transfusions: What you need to know

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Answers to your questions about your child’s transfusion. Learn about the types of blood components, risks of transfusion and alternatives to transfusion.

Key points

  • Blood transfusions are given to patients to provide them with the blood component they need.
  • Blood components are made from the blood of people who give (donate) their blood.
  • There are many types of blood components, including red blood cells, platelets, and plasma.
  • When your child needs a blood component as part of their treatment, the benefits should be greater than the risks.

What is a blood component transfusion?

When your child has a blood transfusion, they are given a blood component to supply them with the part or parts of blood they need.

What are blood components?

Blood cells and componentsRed and white blood cells, platelets and plasma

Blood is made up of several different parts including red blood cells, white blood cells and platelets, all of which are mixed with a pale, yellow liquid called plasma.

Blood can be separated into its different components. Each component of the blood has a different function. Separating blood into parts allows patients to get only the specific part or parts they need.

The main types of blood components include red blood cells, platelets and plasma.

Red blood cells

Red blood cells increase how much oxygen is carried in the blood and is delivered to tissues throughout the body. Red blood cells carry oxygen in the blood to all parts of the body. Your child may get a transfusion of red blood cells if they have lost blood or have anemia. People who have anemia do not have enough red blood cells.


Platelets help the blood to clump (clot) by sticking to blood vessels that have been cut. Your child may bleed and need a platelet transfusion if they have a low number of platelets or if they have platelets that are not working properly.


Plasma is the liquid part of the blood that has proteins such as clotting factors in it. Clotting factors cause the blood to clump and stop flowing out of blood vessels that have been cut.

Plasma may also be made into plasma protein products, such as:

  • Albumin
  • Clotting factor concentrates (used to prevent or control bleeding)
  • Immune globulins (contains antibodies that are used to fight infections or used in some medical conditions).

For more information about plasma protein products, see the article Blood transfusion: Plasma protein products.

Where do the blood components come from?

Canadian Blood Services (CBS) collects blood from volunteers who donate their blood for free. These volunteers answer a long questionnaire, have an interview, and a physical exam or check-up to make sure they are healthy before they are allowed to donate blood.

How is the blood tested?

Each blood donation is tested for the blood group of the donor, for example, the ABO group and Rh factor. This is to ensure that recipients receive blood that matches their blood type.

Donor blood is also tested for infectious diseases. Infectious diseases can be spread from one person to another and are caused by things such as bacteria and viruses. All blood that is donated is tested for:

  • Syphilis, an infection that a person can get from sexual contact
  • Hepatitis B and hepatitis C viruses, which are infections of the liver
  • Human T-cell lymphotropic virus type I and II (HTLV-I/II), which causes a rare form of leukemia or cancer of the blood
  • HIV-1 and HIV-2: Human immunodeficiency viruses that cause AIDS
  • West Nile virus (during West Nile season)

Any donated blood that does not pass the tests for these infections is not used for transfusion.

Products made from plasma (such as albumin and immune globulin go through extra treatment steps with heat and/or chemicals to get rid of any viruses that may remain after testing.

Are there risks with a blood component transfusion?

In general, blood transfusions are considered safe, but there are always some risks.

Most patients do not react to a blood transfusion. But if your child has a reaction, please tell your child's nurse right away.

Allergic reactions – A reaction with the blood product can cause hives or rashes. They are typically mild and easily treated. Serious allergic reactions are rare.

Fever – A fever can result from your child’s body reacting to plasma proteins from the donor’s blood. A fever is typically not severe and easily treated.

Transfusion-related acute lung injury - Donated blood can sometimes cause breathing problems and injure the lungs. For about every 1,200-5,000 plasma-containing transfusions, one person will have this problem.

Bacterial contamination - Bacteria from the donor's skin, an unrecognized infection or contamination can infect the donated blood. This can cause an infection when someone receives the blood. For every 10,000 units of platelets or 250,000 units of red blood cells transfused, one person will have this problem.

Graft versus host disease - If a blood recipient has a weakened immune system and receives a transfusion, the white blood cells from the donor can attack the recipient's body. This condition is called transfusion-associated graft versus host disease (TA-GvHD). It is very dangerous but very rare. For patients with a known weakened immune system, including children with cancer, the Blood Transfusion Lab will treat (irradiate) the donor blood to kill the white blood cells and prevent this problem.

Infectious disease - In Canada, because blood donors are screened and blood is tested, the chance of getting a unit of blood component with a virus in it is very small.

  • The chance of getting HIV (AIDS) is less than 1 in 21 million.
  • The chance of getting hepatitis C is less than 1 in 13 million.
  • The chance of getting hepatitis B is less than 1 in 7.5 million.
  • The chance of getting West Nile Virus is less than 1 in 1 million.

Like any medical treatment, a blood component transfusion has some risks. But when your child needs a blood component as part of treatment, the benefits should be greater than the risks.

Blood components and live virus vaccines

Some blood components may temporarily interfere with the immune response to live virus vaccines. Please discuss these blood components and the timing of upcoming live viral vaccines with your child’s vaccine provider.

What happens if your child needs a blood component transfusion?

Your child's doctor will explain to you why your child needs a blood component transfusion, what the benefits and risks of the transfusion are, and if there are any other treatments your child could have instead of a transfusion. This is part of the informed consent process.

If you agree that your child should have a blood component transfusion, your child's doctor will ask the Blood Transfusion Lab for the blood product your child needs. The Blood Transfusion Lab will then prepare that blood product.

Will I be told if my child has a blood component transfusion?

You will be told if your child had a blood component transfusion. Your child’s hospital record will have information about your child’s transfusion.

Are there alternatives to transfusion for surgery?

Elective surgery is surgery for a condition that is not an emergency. Patients scheduled for elective surgery will be counselled about diet and iron supplementation. This is done to increase their hemoglobin levels before surgery and decrease their chance of needing a red blood cell transfusion during surgery. To avoid transfusion, your child may be able to have either, or both, of the following:

  • Blood salvage: The blood your child loses during surgery is collected and returned during surgery
  • Medicines

Blood salvage

When the doctors think your child's surgery may cause a large loss of blood, they may collect some of the blood that your child loses. They may give that blood back to your child during the surgery.


Some medicines may reduce your child's need for a blood transfusion during surgery:

  • Some medicines lower your child's blood pressure. Blood pressure measures how strongly the heart pushes blood around the body. The use of these medicines will depend on your child's condition and the type of surgery.
  • Some medicines reduce the amount of bleeding by forming clumps of blood, called blood clots, or by slowing the breakdown of the blood clots that are formed. The use of these medicines will depend on your child's condition and the type of surgery.
  • A medicine called erythropoietin may be used before elective surgery to reduce the need for red blood cells during the surgery. Erythropoietin causes the body to make more red blood cells. Iron is also needed to make hemoglobin, the part of the red blood cell that carries oxygen. If your child is given erythropoietin, they will get it by needle once or twice a week for about four weeks before the surgery. Your child will also take iron pills at the same time.

Is there artificial blood?

Artificial blood is not used at this time.

There is no artificial blood or blood made in the laboratory that does all the things that blood does. Substitutes for red blood cells that can carry oxygen are being made in the laboratory, but they are still experimental and are not for general use in Canada at this time.

Can I donate blood for my child?

You may donate blood for your child's use if your blood group matches your child's blood group and if your child:

  • is having elective surgery
  • is very likely to need blood

A donation of blood for a specific patient is called a directed blood donation. Many people feel more comfortable knowing who the blood donor is. But no medical study has shown that directed blood donations are safer than the blood collected from regular blood donors. In fact, directed donation may be associated with an increased risk to the patient. Canadian Blood Services (CBS) allows directed donations only from a parent or legal guardian to their minor child. For more information, see the article Directed blood donation.

Last updated: June 25th 2021