Understanding Blood Types

Ever wondered why there are different blood groups? Which blood group is compatible with yours?

Because not all blood groups are compatible with one another, your blood is crucial to patients with a blood group that is compatible with yours.

Read on to find out more:

1. How many blood groups are there? What do the ‘letter’, ‘+’, and ‘-’ mean?
ABO and Rhesus (Rh) are the two most important blood group systems.

FUN FACT!: There are near to 40 human blood group systems recognized by the International Society of Blood Transfusion (ISBT), with ABO and Rh being just two of them.

Within the ABO system, there are four main groups - A, B, O, AB - determined by the presence or absence of A and B antigens on the surface of red blood cells. If you are group A, this means A markers are present on the surface of your red cells; group AB means both A and B markers are present on the surface of your red cells; while group O means there are no A or B markers on the surface of your red cells.

Within the Rh system, depending on the presence or absence of RhD antigen, you can be either RhD positive (+) or RhD negative (-)

This results in a total of eight main blood groups: A+, A-, B+, B-, O+, O-, AB+ and AB-.

Antigens 8BloodTypesFUN FACT!: Each drop of blood contains 200-300 million red blood cells. Each red cell has more than a million markers on its surface.

2. So what’s the population like for the different blood groups in Singapore?
In Singapore, most people are Rhesus positive (A+, B+, O+, AB+), and less than 1% of the population are Rhesus negative (A-, B-, O- and AB-). Rhesus-negative blood is considered rare and precious because patients who have such blood are recommended to receive Rhesus-negative blood.

For the breakdown of who you can donate your blood to, scroll to the bottom of this page!

3. How do I know what’s my blood type? How is it determined?
ABO and Rhesus testing is performed on each and every unit of blood donated to ensure patient-blood compatibility. If you have donated blood before, you can check your blood group by visiting the online portal (SingPass log-in is required)

4. Which blood groups can my blood help?
Scroll down to view what’s unique about your blood group! To view the full infographics for each blood type, visit our Blood Types Album.

BloodType OposBloodType BposBloodType AposBloodType ABposBloodType OnegBloodType BnegBloodType AnegBloodType ABneg

Your blood is valuable and important. You can save lives as a blood donor!

To make an appointment, visit this link (SingPass login is required) or call 6220 0183.