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Alberta Blood Transfusion Information

When your child needs special red blood cells or platelets

​​​​​​​​​​​​​​​​During treatment for your child’s health condition, they may get a blood transfusion with blood products such as red blood cells or platelets.

Many blood products need special processing in the transfusion lab before they can be given. This takes time, so it may take longer than usual before your child gets the blood product. If you have questions, talk to your child’s healthcare provider. Special processing may include irradiation and washing. These processes are described below.

Red blood cells (RBCs)

Red blood cells help carry oxygen in your blood to all your organs and cells. One unit of red blood cells is about 250 to 350 mL (about 1 cup). Sometimes, 1 unit might not be the amount that your child needs. If this happens, your healthcare provider may order part of a unit.

Antigens and antibodies

An antigen is a substance that causes, or triggers, your immune system to make cells that attack and try to destroy that substance. These cells are called antibodies. Your body usually makes 1 specific type of antibody for each antigen.

Antibodies are protein cells made by your body's natural defense system (immune system). These cells help to fight foreign or harmful substances. Your body can make antibodies against red blood cells or platelets you get from a blood donor. If this happens, you may need to get antigen-negative red blood cells or human leukocyte antigen (HLA) matched platelets.

What are antigen-negative red blood cells?

Antigen-negative red blood cells have been tested to make sure they don’t have antigens that your child may already have made an antibody to. These special red blood cells may be used for regular blood transfusions or exchange transfusions. There’s less of a chance that your child will react to these. Finding donated blood with these special red blood cells might take more time.

Your child might get antigen-negative red blood cells if they have a red blood cell antibody. If your child is on a prevention program for people with hemoglobin disorders like sickle cell disease or thalassemia, these special red blood cells may also be used. This type of prevention program makes sure that many of the antigens on the red blood cells are matched before they’re given.

Does it matter how long it’s been since the red blood cells were donated?

The freshest or most recently donated units of red blood cells aren’t always the most appropriate ones. Your child will get the most suitable red blood cells for their condition.


Platelets are cells in your blood that your body needs to stop bleeding (clot).

What are human leukocyte antigen (HLA)-matched platelets?

Human leukocyte antigens (HLA) are a special type of antigen that platelets have. Sometimes your body can make antibodies to HLA antigens on platelets. Platelet transfusions may be less effective if this happens.

HLA-matched platelets are similar to antigen-negative red blood cells. HLA-matched platelets have been tested for these special antigens to make sure they’re negative for the antigen you have made antibodies for. They also test for antigens you might make antibodies for.

These platelets can be hard to find depending on the donations available. Sometimes these platelets have to be brought in from other cities.

Irradiated blood products

What does irradiated mean?

Irradiated means the red blood cells or platelets are exposed to radiation (by x-ray or another form of radiation). This is done to prevent a serious disease called transfusion-associated graft versus host disease (TA-GVHD).

What is TA-GVHD?

TA-GVHD is a rare, but serious complication of blood transfusions. It’s caused by white blood cells (lymphocytes) in the transfused donor blood. Sometimes a few of these donor white cells may recognize your cells as different. They can start to attack your own cells. This can cause a serious illness or even death.

You may be at risk for TA-GVHD if you have a weak immune system from:

  • treatments that suppress or lower your immune system (such as for aplastic anemia)
  • certain types of medicine (such as Fludarabine)
  • a treatment you got during a bone marrow or stem cell transplant
  • a transfusion from a family member (directed donation)

How does irradiation work?

The radiation makes the lymphocytes inactive. This stops them from dividing and causing harm.

Does irradiation damage the blood?

No. Red blood cells and platelets still work the way they should even after they’re irradiated. This procedure is safe. The blood doesn’t become radioactive and it won’t harm your child or anyone around them.

Is all blood irradiated?

No. This is only done for people who need this before they get blood products. Some hospitals always have a supply of irradiated red blood cells and platelets. Other hospitals irradiate blood as it’s needed for people at risk for TA-GVHD. It takes about 10 minutes. If other processing is needed it can take longer for the blood product to be ready to use.

Washed blood products

What is washed blood?

Red blood cells and platelets are washed to remove plasma proteins that may cause your child to have a transfusion reaction. This may be done if your child has had transfusion reactions before or has antibodies against Immunoglobulin A (IgA). Immunoglobulins help your body’s immune system protect you by fighting off bacteria or viruses.

It takes up to 2 hours to wash blood. For safety reasons, the washing process doesn’t start until your child has arrived and is ready to get the transfusion. This is important (especially for platelets) so that a blood product that may have been specially prepared for your child doesn’t get wasted or thrown out.

If you have questions about the blood products your child needs, talk to your child’s healthcare team.


Current as of: April 7, 2021

Author: Transfusion Medicine Safety Program, Alberta Health Services