It can be helpful to know your blood type to prevent the risk of receiving incompatible blood at the time of need, such as during a blood transfusion or during surgery. If the wrong types of blood are mixed - it can lead to a clumping of blood cells that can be potentially fatal.
Categorizing blood according to type helps prevent reactions when someone gets a blood transfusion. Red blood cells have markers on their surface that characterize the cell type. These markers (also called antigens) are proteins and sugars that our bodies use to identify the blood cells as belonging in us.
The two main blood groups are ABO and Rh.
The ABO blood system has four main types:
Type A: This blood type has a marker known as A.
Type B: This blood type has a marker known as B.
Type AB: This blood type has both A and B markers.
Type O: This blood type has neither A or B markers.
The other group, Rh is pretty simple
+ has the Rh marker
- doesn’t have the Rh marker
Based on the above, there are 8 total different blood types
O negative. - This blood type doesn't have A or B markers, and it doesn't have Rh factor.
O positive. - This blood type doesn't have A or B markers, but it does have Rh factor. O positive blood is one of the two most common blood types (the other being A positive).
A negative. - This blood type has A marker only.
A positive. - This blood type has A marker and Rh factor, but not B marker. Along with O positive, it's one of the two most common blood types.
B negative. - This blood type has B marker only.
B positive. - This blood type has B marker and Rh factor, but not A marker.
AB negative. - This blood type has A and B markers, but not Rh factor.
AB positive. - This blood type has all three types of markers — A, B, and Rh factor.
Who can you donate blood to
A patient can receive blood that has the same ABO markers as theirs. O+ can receive + or - while - must receive - blood.
Here is a quick table of blood types and who you can donate or receive blood from.
|Your blood type||You can donate blood to||You can receive blood from|
|O +||O+ or A+ or B+ or AB+||O+ or O-|
|A +||A+ or AB+||A+ or A- or O+ or O-|
|B +||B+ or AB+||B+ or B- or O+ or O-|
|AB +||AB+ is the only group you can donate to||All blood types|
|O -||All Blood Types||O - Only|
|A -||A- or A+ or AB- or AB+||A- or O-|
|B -||B- or B+ or AB- or AB+||B- or O-|
|AB -||AB- or AB+||AB- or A- or B- or O-|
The most needed blood type by blood banks is O- because this person can donate blood to anyone else. The person with AB+ can receive blood from all other donors.
In trauma situations, when the emergency staff doesn’t have time to figure out the patients blood type and perform a cross match, only O- blood is given until their blood type is determined to prevent adverse transfusion reactions.
After the emergency situation, the patient is then reverted to their own blood type.
O- is given to prevent a patient from developing antibodies to the D antigen (aka Rh factor, the thing that makes a blood group positive or negative). This is especially important in women of child-bearing age - if a pregnant women is A-, for example, and the baby is A+ due to the father having the D antigen, there's a chance that the mother could develop an anti-D antibody that can be fatal to the fetus.
Its important to know that none of this makes a person better, healthier or stronger. While doing research for this article I came across a number of websites claiming otherwise. Apparently its all the rage in some Asian countries - you are even asked your blood type on the first date!