News & Blogs
July 13 2020

Blood Typing: How Does it Work?


Blood is the fluid of life for many different reasons. Even though it may not be an organ like the heart, its role in maintaining the body is just as important. Having healthy blood generally means that a person is also healthy. As one of the most complex fluids in the body, it serves three main purposes:
1. Transport –  Blood transports oxygen and other essential gasses. It is also in charge of delivering vitamins and minerals throughout the body’s systems.
2. Protection – The blood is one of the body’s main lines of defense. It contains leukocytes (white blood cells), which eliminate invading microorganisms and prevent pathogens from spreading.
3. Regulation – Blood regulates fluids and maintains the body’s pH levels. To balance the water inside the body, it transfers fluids to and from tissues.
With these functions in mind, there is no denying that blood is a vital component of the body’s biochemistry. In the unfortunate event that a person acquires a blood-related disease or gets involved in an accident where there is massive blood loss, a transfusion will be needed for proper treatment.
A blood transfusion can be a matter of life and death, so blood typing is required for a safe procedure.
Different Blood Types 
It should be clear by now that not all blood is the same. So, how exactly does blood typing work? To understand this process better, learning about the different blood types is the first step.
The four (4) main blood groups consist of the following:
  • A – Blood with only the A antigen in the red cells and B antibody in the plasma
  • B – Blood with only the B antigen in the red cells and A antibody in the plasma
  • AB – Blood with both the A and B antigens in the red cells but neither A nor B antibody in the plasma
  • O – Blood with neither the A nor B antigens in the red cells but have antibody A and B in the plasma
A blood test is used to determine the presence or absence of antigens A and B in one’s blood. A patient’s blood is collected, then mixed with specific antibodies. Its reaction will signify the blood type.
Once identified, a blood factor test will be done to determine the presence of Rhesus (Rh), a protein found on the surface red blood cells. It follows a similar procedure—mixing a sample of the blood with other substances and observing the way it reacts.
Being Rh-positive is the most common type, but having an Rh-negative blood type is not really a bad thing, though the presence or absence of the Rh factor plays a critical role in a woman’s pregnancy. The mother will need special care if she and the baby have Rh compatibility since her blood will create antibodies that will work against the fetus’s blood.
After taking note of the two details, experts will be able to identify which blood type ( A+, B+, AB+, O+, A-, B-, AB-, O-) a patient belongs to.
Blood Compatibility
Antigens are responsible for triggering certain reactions in the immune system. If a patient’s blood is not compatible with a donor’s sample, the body may see the transfused blood as a foreign or harmful substance. Instead of speeding up the healing process, the cells in the transfused blood will be eliminated.
This is primarily the reason why blood typing is so important. Once a doctor has figured out the blood type of a patient through crossmatching, transfusions, and organ transplants can be successfully done. To simplify things further, here is how compatible each blood type is to one another.
Blood Type Can Donate To Can Receive From
A + A+ AB+ A+ A- O+ O-
A - A- A+ AB- AB+ A- O-
B+ B+ AB+ B+ B- O+ O-
B- B- B+ AB- AB+ B-  O-
AB+ AB+ Only All blood types
AB- AB- AB+ AB- A- B- O-
O+ O+ A+ B+ AB+ O+ O-
O- All blood types O- only
Source: The Blood Center
Incompatibility Reaction
Blood transfusion is generally safe, but mild allergic reactions may still happen, even if a person receives the right blood type. In case a patient receives incompatible blood, a serious complication called a hemolytic transfusion reaction might occur.
After the blood has been transfused, the recipient’s immune system will destroy the donated blood cells over time (hemolysis). Once the cells are ripped apart, harmful chemicals are released within the patient’s body, leading to an intense, flu-like illness.
Even with full treatment measures, falling victim to this error will eventually cause organ failure, shock, and potentially death.
Nowadays, blood transfusions are screened carefully, so these types of accidents barely happen. As long as patients seek help from competent and trustworthy health professionals, incompatibility reactions will not be a concern.
The Fluid of Life
According to the Red Cross, over 4.5 million lives are saved each year by blood transfusions. If you want to give back to the community while experiencing multiple health benefits, make it a point to donate blood regularly.

In case you have specific health concerns, do not hesitate to reach out to Makati Medical Center for help. Contact us today for concerns regarding blood typing, blood donations, and safe blood transfusions.