How blood transfusions work

2 min read

SCIENCE

Our bodies need blood to deliver oxygen and nutrients and remove waste. How do we receive more when we run dangerously low?

WORDS AILSA HARVEY

When a person loses blood due to injury or illness, preventing the body from functioning effectively, blood from another person may be needed. This is carried out through a blood transfusion. Transfusions rely on millions of blood donations around the world, sorted into blood types that match a patient’s specific blood group to reduce the chance of their body rejecting it.

Blood donors give around 470 millilitres of blood per donation – about eight per cent of the average adult’s blood volume – which takes between five and ten minutes. This is tested to make sure it’s categorised into the right blood type and has no trace of disease. Because men generally have more iron in the blood than women, they can donate blood every 12 weeks, while women need to wait 16 weeks between donations. Not all blood transfusions require the blood of a separate individual. Autologous, or selfdonation transfusions take place when a patient is donating blood for themselves in the future. This is usually for a preplanned surgery where the blood loss is predicted to be 20 per cent or more. Some examples of such operations include organ transplants, joint replacements and heart surgery.

RECEIVING BLOOD

How does the process of a blood transfusion work?

TYPES OF TRANSFUSIONS

Blood transfusions are usually given because a specific component in the blood needs to be boosted in quantity. The main types of blood transfusions are red blood cells, platelets, plasma and whole blood. Red blood cells are the most common blood cell and hold the main role of delivering oxygen around the body. When a patient experiences significant blood loss due to injury or suffers from anaemia – acondition that causes the body to have a lower red blood cell count – ared blood cell transfusion takes place. Some anaemic patients require this procedure every few months.

Platelets are large cells in the blood that clump together when tissue bleeds. This forms a clot to prevent significant blood loss. Patients with low platelet counts, such as chemotherapy patients who have

This article is from...

How It Works Magazine

3 August 2023

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