World Blood Donor Day 2024: Understanding Blood Type and their Importance in Blood Donation - Dr Rahul Katharia

ABO is the human blood grouping system that groups the blood into different types, based on the presence or absence of certain markers on the surface of red blood cells. A blood group is a system that allows to determine whether your blood is compatible or incompatible with someone else’s blood.

There are four major blood types: A, B, AB and O making it eight blood types combined with ABO and Rh blood group systems: A positive (A+), A negative (A-), B positive (B+), B negative (B-), AB positive (AB+), AB negative (AB-), O positive (O+), O negative (O-). The most common blood type is O positive (O+) and the least common blood type is AB negative (AB-).

Rhesus factor

The red blood cells are also determined for Rh factor, also known as the RhD antigen. If the red blood cells contain the RhD antigen, they are RhD positive. If they do not, they are RhD negative.

What determines your blood type?

Blood types are determined by the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body. Since some antigens can trigger a patient's immune system to attack the transfused blood, safe blood transfusions depend on careful blood typing and cross-matching

Rare blood types

Apart from ABO system, there are minor blood group antigens across than 40 different blood group systems attached to red cells. To name a few, such as Duffy blood group. K antigen (or Kell) group, Kidd blood group. They are important in patients who undergo regular transfusion, such as thalassemia and sickle cell anaemia. One of the world’s rarest blood types is Rh-null. It’s so rare that it’s sometimes called as “golden blood.”

How are blood types inherited?

The blood type is inherited the same way as you inherit your other genetic information from your biological parents. Both the ABO genes and the Rh factors come from your parents. Due to the many possible combinations, you might not have the exact same blood type as your parents.

Which blood types are compatible?

An important part of blood donation is ensuring that someone receiving blood (recipient) has a compatible blood type with someone donating blood (donor).

Why you should know your blood type?

Medical reasons:The most important reason to know your blood type is in case of an emergency. If you are in a situation where you require a blood transfusion, you will need a compatible blood.

Help others: One of the best, and most selfless, reasons to know your blood type is to help others through blood donations.

Plan a healthy pregnancy: Knowing your blood type can help predict some conditions that can occur during pregnancy, such as Rh incompatibility between mother and baby. A fetus may inherit its Rh factor (either positive or negative) from either parent.

There may be problems if the mother is Rh negative and carrying a fetus with blood with Rh positive. Rh immunoglobulin (RhIg) is given, which blocks antibodies from attacking the fetus blood for prevention.

Lower risk for certain health conditions: Most of the time, blood typing helps you safely donate and help others, but it can also let you know if you are at risk for certain health conditions in the future.

Studies have shown connections between blood types and the risk of blood clots, bleeding and kidney stones. Blood type is just one factor that contributes to your risk, make sure to visit the physician and maintain a healthy lifestyle.

Universal donor and universal recipient: O negative blood contains no A, B, or RhD antigens. Almost anyone with any blood type can receive these red blood cells. A person with group O negative blood is a universal donor. Blood type AB positive (AB+) is the universal recipient.

Can your blood type change?

In rare cases, blood types can change, usually relates to unique circumstances, such as having a ABO incompatible stem cell or bone marrow transplant or getting certain types of leukaemia or infections.

The ABO system is the best-known way of classifying blood types. O positive is the most common, and AB negative is the rarest. Blood donations save lives every day, but receiving the wrong type of blood can lead to life-threatening consequences.