• Home
• About us
  • History
  • Mission / Vision
  • Standards of Practice
  • Governance
  • Annual Report
  • Access to Info
• Donors
  • General Info
  • Types of Donors
    • Regular donors
    • Platelet donors
    • Autologous/Designated
    • Senior Citizens
  • Donor Questionaire
  • Clinic Schedules
  • Enrol as donor
• General
  • Groups
  • How blood is used
  • Questions
  • Tourists
• News
  • Press Releases
  • Photo gallery
  • Newsletter
• Doctors
  • Clinician's site
• Contacting us
  • Regions
  • Contact us
  • Update your details

Blood is categorised according to two different systems, the ABO system and the Rhesus system.

The ABO blood grouping system

The discovery of the ABO blood group system in 1901 by Karl Landsteiner was the primary basis for the clinical discipline of blood transfusion as we know it today.

Based on the correlation of visible clumping in mixtures of plasma and red cells in healthy individuals, people are categorised into one of four blood groups — A, B, AB and O.

Rhesus System

The Rhesus (Rh) blood grouping system is routinely typed for along with ABO. Although it is a complex system, individuals are categorised into two groups Rh+ or Rh-. The vast majority of individuals (85%) are Rh+ although there are racial differences in frequency.

Importantly, blood group A individuals have naturally occurring anti-B blood group antibodies in their plasma, blood group B has anti-A blood group antibodies and blood group O has anti-A and -B blood group antibodies.

If a blood group B patient is given blood group A, the anti-A antibodies in their plasma will destroy the red cells in the transfused unit and lead to severe complications or even death.

Blood group O Rh- individuals are known as "universal donors" because they lack A and B blood group antigens which makes it possible for their blood to be given to all ABO types.

AB+ blood group individuals are known as "universal recipients" because they lack naturally occurring anti-A and -B and can receive all ABO groups.

The WPBTS takes great care in correctly grouping donated blood and performs cross matches to ensure compatibility.

The Rh system is also important for blood transfusion. If an Rh- patient is given Rh+ blood, there may be a delayed destruction of the patient's red cells. The reaction is usually not as severe as an ABO mismatch, but severe reactions can occur.

Blood group distribution in South Africa

The general distribution of blood groupings in South Africa is illustrated in the table below.

It is important to note that it may vary between specific regions and particular racial or ethnic groups.

The terms "universal donor" and "universal recipient" were coined when it was demonstrated that it is relatively safe to give O- blood to patients of any blood group, and that blood from all groups can be given to AB+ patients.

The chart above illustrates that group O blood is the most versatile.

Adequate stocks of group O blood are vital for two reasons 1. O- can be given to all patients. 2. More individuals have O+ blood than any other group, and only a group O donor can help a group O patient.

The components of blood

Blood (called "whole blood") can be separated into four basic components:

• Red blood cells
• White blood cells
• Plasma
• Platelets

While whole blood is used only in case of severe blood loss due to surgery and trauma or for exchange transfusions in infants, most donations are separated into transfusable components through a special spinning or centrifugation process.

Transfusion patients will only be treated with the particular component or blood product that their injury or illness requires.

Each donation that the WPTS received is used as effectively as possibly and can therefore contribute to saving up to four lives.

Red blood cells carry oxygen and nutrients to the tissues where it also picks up and returns carbon dioxide to the lungs where it is exhaled from the body. These essential cells must be used within 42 days of donation or can be frozen.

White blood cells are disease fighters that attack and eradicate viruses and infections from the body.

Plasma comprises approximately half of each unit of whole blood. It is the liquid which literally floats the cells throughout your body and contains nutrients and proteins. It is used primarily as a source of clotting factors, for the replacement of blood volume and the production on albumin, a protein used the treat severe shock, burns and blood loss.

Cryoprecipitate is a small portion of plasma that is harvested using a freeze-thaw process. It contains factors to help blood clot and is used primarily as a source of clotting factor VIII for patients with classic haemophilia.

Platelets help blood clot and are given mainly to patients with bone marrow production problems and in the treatment of illnesses such as leukaemia. Platelets must be harvested within eight hours of donation and are stored at room temperature in a gently agitated state so as to be functional when transfused. They must be used within five days of donation.