Definition and Overview

A blood transfusion is a common medical procedure wherein a patient receives blood (which can be from a donor or blood bank) through an intravenous (IV) line. This becomes necessary in case of severe blood loss, which can be due to an injury, illness, or surgical procedure.

The most important aspect about transfusions is making sure the blood used is compatible with the patient’s blood type; otherwise, complications may occur. This procedure is not without risks, so a strict and proper process has to be followed when a transfusion is necessary, and patients undergoing it are placed under close monitoring in case complications arise.

Who Should Undergo and Expected Results

Blood transfusion, as mentioned earlier is performed when a person experiences severe blood loss, which could be due to a major surgery, traumatic injury, and childbirth, among others.

Aside from blood loss, there are also some blood-related disorders that can affect a person’s amount of blood supply. These include:

  • Anemia – This is a medical condition characterised by abnormally low levels of red blood cells. Transfusions are usually used as a last resort when other treatments for anemia have failed.
  • Thalassaemia – This is a health condition wherein the body’s production of red blood cells is disrupted.
  • Acute myeloid leukemia
  • Lymphoma
  • Sepsis
  • Severe infection
  • Thrombocytopenia
  • Liver cirrhosis

Blood loss or the reduced production of one or more parts of the blood could also be caused by some types of cancer treatments.

Blood transfusions are expected to:

  • Aid in treatment
  • Restore the body to its normal functioning level
  • Save the patient’s life

How Does the Procedure Work?

A normal blood transfusion process usually takes up to four hours, but this may vary depending on how much blood is needed. Prior to the procedure, the patient’s blood type is taken so that only blood with the correct type will be used. It will also be determined whether the patient needs blood as a whole or only specific parts, which means a person may only be given red blood cells, white blood cells, plasma, or platelets, depending on what his body requires.

  • Red blood cells transfusion - A person requiring a transfusion due to a severe case of anemia will need only red blood cells.

  • Platelets transfusion – A person who has undergone chemotherapy or a bone marrow transplant may have reduced platelets as a side effect and will thus benefit from a platelet transfusion.

  • Plasma transfusion – A plasma transfusion usually becomes necessary with severe blood loss or when there is a problem with the proteins that cause blood to clot.

  • White blood cells transfusion – This is the least commonly used type of transfusion. It only becomes necessary in case of an infection that does not respond to antibiotics. Adding more white blood cells will help the body fight the infection.

Correct blood typing is very important in a transfusion to avoid allergic reactions. Humans can have four different blood types, namely A, B, AB, and O. Each person is also either Rh-positive or Rh-negative. So a person with blood type A will be either A-positive or A-negative. This blood type will determine which blood is safe for the patient. Patients with blood type A can only receive types A and O, and patients with blood type B can only receive types B and O. Patients with blood type AB, which is known as the universal recipient, can receive any type of blood. On the other hand, blood type O is known as the universal donor, as it is safe for everyone, which is why it is the type that is used in emergency situations when there is no time for blood typing. However, people with blood type O can only receive either type O or type AB.

Also, whether a person is Rh-negative or Rh-positive also impacts the type of blood that he can receive in a transfusion. A person who is Rh-positive can receive both Rh-positive and Rh-negative blood, but a person who is Rh-negative can only receive the same Rh-negative blood.

Although blood is easily available through blood banks, in some cases, patients also have the option to use their own blood for a planned transfusion, such as those performed after a major surgery. To do so, the patient will have some blood drawn before undergoing the surgery; this blood will then be stored in a blood bank and will be given back to the patient after the surgery.

Once the correct blood is available, a plastic tube is inserted into a vein in the patient’s arm. The tube, called a cannula, is where the blood passes through. Sometimes, a bigger cannula is used, but it is inserted into a chest vein. The cannula is then connected to a drip that delivers the blood at a certain rate. Patients will usually feel some discomfort when the cannula is inserted, but the transfusion itself is painless.

After the procedure, the patient will be brought to a recovery room where he will be closely monitored to make sure the body accepts the blood well.

Possible Risks and Complications

Blood transfusions come with certain risks and possible complications. These include:

  • Allergic reaction – This occurs when the body does not respond well to the donated blood and instead suffers from an allergic reaction. However, these allergy attacks are usually temporary and may resolve on their own after some time, although doctors can also prescribe some antihistamines or paracetamol to lessen the symptoms. They may also only cause mild symptoms such as itchy skin rashes, swollen limbs, headaches, and dizziness. However, if a person experiences high fever, chills, shivering, swollen lips, swollen eyelids, and difficulty breathing after a transfusion, it is best to seek medical help.

  • Anaphylaxis – This refers to a more serious form of allergic reaction to donated blood. It occurs when the immune system overreacts to the proteins and other substances in the new blood. Anaphylaxis causes more severe allergy symptoms such as breathing difficulties, clammy hands and feet, and fainting. A person experiencing anaphylaxis needs to be given an injection of adrenaline immediately.

  • Transfusion-related acute lung injury (TRALI) – This refers to a serious but very rare condition caused by an abnormal immune response more commonly after a platelet or plasma transfusion. In cases of TRALI, the patient’s lungs have been inflamed around six hours after the transfusion and are deprived of oxygen. Thus, patients need artificial oxygen supply until the inflammation resolves.

  • Haemolytic transfusion reaction (HTR) – This occurs when the immune system attacks the cells of the donated blood, mistaking them for harmful foreign substances. It can occur within a few hours or a few days after the procedure, and will cause the patient’s urine to become darker as the red blood cells are attacked and destroyed. This is the kind of reaction that the body has when the wrong blood type is used in a transfusion.

  • Blood contamination – This is another very rare risk as doctors and blood banks nowadays are very careful in testing donated blood. Blood contamination occurs when the donated blood is contaminated either with bacteria or a virus. The risk is highest with platelet contaminations since platelets have to be handled properly and kept at a specific room temperature to prevent the growth of bacteria. Contamination may cause symptoms such as high fever, chills, rapid breathing, clamminess, and confusion.

  • Fluid overload – In rare cases, a patient may receive too much blood, causing an overload. This risk is higher among patients with low body weight. If this occurs, the patient has to take an oral diuretic, which will help flush out the excess fluid from the body. If left untreated, fluid overload can lead to heart and lung problems as these vital organs become filled with fluid.

There are now strict handling and testing processes in blood banks, so these risks and possible complications are very rare.

  • Cushing MM, Ness PM. Principles of red blood cell transfusion. In: Hoffman R, Benz EJ Jr, Silberstein LE, et al., eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 112.

  • Hall BA, Chantigian RC. Blood products, transfusion, and fluid therapy. In: Hall BA, Chantigian RC. Anesthesia: A Comprehensive Review. 5th ed. Philadelphia, PA: Elsevier; 2015:chap 5.

  • U.S. Food and Drug Administration. Blood and blood products. Rockville, MD: U.S. Department of Health and Human Services, U.S. Food and Drug Administration. Last updated March 10, 2014. Available at: Accessed October 7, 2015.

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