A blood transfusion may be done when you have lost blood because of an injury or during surgery. It can also be done because of diseases or conditions that affect the blood. Blood is made up of several different parts (blood products). You may get some or all of these blood products during a transfusion. Blood for transfusion is usually donated by another person (donor). Strict measures are taken to make sure that donated blood is safe before it's given to you. This sheet helps you understand how a blood transfusion is done. Your doctor will discuss your condition with you and answer your questions.

Blood can be broken down into different parts that have special roles in the body. These parts include:

• Red blood cells, which carry oxygen throughout the body.
• Platelets, which help stop bleeding.
• Plasma (the liquid part of blood), which carries red blood cells and platelets throughout the body. Plasma also helps platelets in stopping bleeding. Plasma also contains important clotting factors to help the blood clot.

• Volunteer donors. These are people who donate their blood to help others in need of blood. Blood donation can take place at several places, including a hospital, blood bank, or during a blood drive.
• Directed donation. If you need a blood transfusion during a planned surgery, family and friends can have their blood tested for compatibility and donate blood for you before the surgery. This needs to be done at least 7 days in advance. This is because the blood must be tested for safety, just as blood from volunteer donors is tested. Blood from directed donors has not been shown to be safer than blood from volunteer donors. Talk with your doctor about directed donation.
• Autologous donation. This is also called self-donation. For planned surgery, you can donate your own blood starting up to 6 weeks before surgery. Talk with your doctor about self-donation to see if it's a choice for you.

Donated blood is tested and processed to make sure that it's safe:

• The health history of each donor is carefully screened. If a person is considered high-risk for infection or problems, they aren't accepted as a blood donor.
• Donated blood is tested for infections such as hepatitis, syphilis, and HIV (the virus that causes AIDS). If the tested blood is found to be unsafe, it's destroyed.
• Blood is divided into four types: A, B, AB, and O. Blood also has Rh types: positive (+) and negative (-). You can only get blood products that are compatible with (match) your blood type. A sample of your blood is tested for compatibility with donated blood. This is done before blood products are prepared for a transfusion.

A blood transfusion takes place in a blood center, infusion center, hospital room, or operating room. Your doctor will discuss the blood transfusion with you before it's done. You'll need to give permission for the blood transfusion by signing a consent form.

• Your doctor confirms your identity. They also confirm that they have the correct blood products for you.
• An I.V. (intravenous) line is placed in a vein if you don't already have an I.V.
• The blood product comes in a plastic bag that is hung on an I.V. pole. The blood product flows from the bag into your I.V. line. The I.V. line is connected to a pump, which controls the transfusion rate. You may get more than one kind of blood product through the I.V.
• Your blood pressure, heart rate, respiratory rate, and temperature are checked throughout the transfusion. This is to make sure you are not having a reaction to the blood product.
• The I.V. line may be removed once the transfusion is complete.

Most transfusions are problem free. In some cases, reactions occur. Most are mild. But rarely, serious and life-threatening reactions can occur. These can happen within seconds to minutes during the transfusion or a week to a few months after the transfusion. Contact your doctor right away if you have any of the symptoms in the table below. In some cases, you may be told to go to the nearest emergency room.