Medically reviewed by Meredith Goodwin, MD, FAAFP — Written by Adam Felmale — Updated on June 3, 2020

The exact amount of blood in a person’s body will depfinish on their dimension. In addition, the blood’s composition varies between individuals. This difference in framework is what provides a person’s blood form.

You are watching: People with type ab blood are considered the "universal recipient" for transfusions because


An individual’s blood type relies on which genes they inherited from their parents.

ABO is the best-well-known device for grouping blood types, though there are other methods. Tbelow are four significant categories within the ABO group: A, B, O, and AB. Within these groups, there are a even more eight blood forms.

Eexceptionally 2 seconds, a person in the USA requirements blood. When a perboy demands a transfusion, medical professionals should give them the appropriate kind. The wrong blood form can cause an adverse reactivity that can be life-threatening.

How does blood occupational, and what troubles deserve to arise?


What makes a blood type?

*
Share on PinterestBloomberg Creative/Getty Images
The main components of blood are:

red blood cells, which bring oxygen approximately the bodywhite blood cells, which play an important role in the immune systemplasma, which is a yellowish liquid that has proteins and saltsplateallows, which enable clotting

The blood group will certainly depfinish on which antigens are on the surconfront of the red blood cells.

Antigens are molecules. They deserve to be either proteins or sugars. The forms and also attributes of antigens deserve to differ in between people, because of tiny genetic distinctions.

The antigens in blood have various attributes, including:

delivering other molecules into and also out of the cellmaintaining the framework of red blood cells detecting undesirable cells that might reason illness

Scientists use two types of antigens to classify blood types:

ABO antigensRh antigens

Antigens and antibodies play a function in the immune system’s defense device.

White blood cells create antibodies. These antibodies will taracquire an antigen if they consider it a foreign object.

This is why it is necessary to match blood kinds when a perboy needs a transfusion.

According to the Amerideserve to Red Cross, If a perboy receives red blood cells through antigens that are not already existing in their mechanism, their body will refuse and attack the brand-new red blood cells.

This deserve to cause a serious and perhaps life-threatening reaction.

How much blood is in the humale body?


ABO and the many prevalent blood types

The ABO blood team system classifies blood types according to the different forms of antigens in the red blood cells and antibodies in the plasma.

They usage the ABO system alongside the RhD antigen condition to determine which blood type or kinds will enhance for a safe red blood cell transfusion.

Tright here are four ABO groups:

Group A: The surchallenge of the red blood cells consists of A antigen, and also the plasma has actually anti-B antibody. Anti-B antibody would certainly assault blood cells that contain B antigen.

Group B: The surconfront of the red blood cells consists of B antigen, and the plasma has anti-A antibody. Anti-A antibody would certainly assault blood cells that contain A antigen.

Group AB: The red blood cells have both A and B antigens, however the plasma does not contain anti-A or anti-B antibodies. Individuals through type AB deserve to obtain any type of ABO blood kind.

Group O: The plasma contains both anti-A and also anti-B antibodies, yet the surconfront of the red blood cells does not contain any A or B antigens. Because these antigens are not existing, a person with any kind of ABO blood kind can receive this kind of blood.

Rhesus factor

Some red blood cells have actually Rh factor, also recognized as the RhD antigen. Rhesus grouping adds an additional measurement.

If the red blood cells contain the RhD antigen, they are RhD positive. If they do not, they are RhD negative.

Understanding ABO and also Rhesus

Doctors must take right into account both ABO and also Rh once considering blood kinds. This suggests tright here are eight main blood kinds in the ABO/Rh blood group device. Some are even more widespread than others.

According to the Amerideserve to Association of Blood Banks, the circulation of blood forms in the UNITED STATE are as follows:


ABO blood typePercentage of people
A-positive (A+)30%
A-negative (A-)6%
B-positive (B+)9%
B-negative (B-)2%
AB-positive (AB+)4%
AB-negative (AB-)1%
O-positive (O+)39%
O-negative (O-)9%

Around 82% of world in the UNITED STATE have Rh-positive blood. The raremainder blood group kind is AB negative.

These are the primary types. Within the eight major groups, are there additionally many kind of lesser-recognized and less widespread blood kinds.

Universal donor and global recipient

O negative blood contains no A, B, or RhD antigens. Almost anyone via any kind of blood kind have the right to get these red blood cells. A perboy through team O negative blood is a global donor.

A perboy through O-negative blood have the right to donate to practically anyone.A perchild via Rh-negative blood deserve to donate to a person with Rh-negative or Rh-positive blood. A perchild through Rh-positive blood have the right to only donate to someone through Rh-positive blood.

As a result, there is a high demand also for O negative blood, even though fewer than 10% of the UNITED STATE population has this type.

The rules for plasma are the opposite of those for Rh. A global plasma donor will certainly have form AB blood.


Before a perboy receives donated blood, medical professionals will certainly examine that this blood is compatible. Giving someone the wrong blood kind have the right to result in potentially life-threatening reactions and complications.

If someone with team B antigen receives red blood cells from someone through team A antigen, their body will launch an immune response and disapprove the transfusion. The anti-A antibody in the recipient’s plasma will attack and also damage the A antigen donor red blood cells.

When the recipient’s plasma strikes and also destroys the donor cells, the blood may clump, or agglutinate. This have the right to result in blood clots, which have the right to obstruct blood vessels. If they break, hemoglobin can leak out, and this have the right to be toxic.

Other feasible adverse effects incorporate allergic reactions and anaphylaxis. In some situations, the body have the right to cope, yet others deserve to be life-threatening.

Some reactions take place at as soon as, while others have the right to take approximately 28 days to appear.

In enhancement, blood have the right to periodically contain unsupposed antibodies, viruses, or parasites. The donor might not have actually symptoms, however they have the right to influence a recipient’s health and wellness.

Doctors and also various other experts conduct stringent testing and screening before a person have the right to obtain donated blood, plasma, or various other blood products.

Find Out more about the benefits and also dangers of donating blood and also the side impacts and also danger of donating plasma.


If 2 parental fees have actually different blood kinds, the mother will not necessarily have the very same blood type or Rh variable as the kid.

If the mother has actually Rh-negative blood, and the boy has Rh-positive, this have the right to pose a threat during pregnancy and also shipment.

A tiny number of red blood cells from the fetus’ circulation have the right to cross the placenta and also enter the mother’s bloodstream. Anti-RhD antibody can then construct in the mother’s plasma, in a procedure well-known as sensitization.

A problem have the right to arise if this antibody then detects a “foreign” antigen in the fetus’ blood cells. The antibodies may begin to assault the fetus’ red blood cells as a defense device.

In some instances, serious jaundice deserve to outcome, and also probably brain damage.

An injection of anti-RhD immune globulin G deserve to assist proccasion the mother from developing this antibody and reduce the affect of a sensitizing event on the fetus.

If a woguy has actually Rh-negative blood, a medical professional may carry out anti-D immunoglobulin at 28 weeks and 34 weeks as a preventive meacertain, according to the World Health Organization (WHO).

Blood trial and error during pregnancy have the right to predict feasible dangers by checking whether the fetus’ blood type is compatible through the mother’s.


A blood test have the right to determine an individual’s blood type.

To test blood, a healthcare provider will take a little sample, normally from the person’s arm.

In a lab, a technician mixes the individual’s blood with 3 various substances to see how they react. Each substance will certainly contain A antibodies, B antibodies, or Rh variable.

See more: Which Is The Correct Lewis Structure For Acetylene C2H2 )? Question #9A0C3

The antibodies will certainly reason a various reaction in each situation. If the blood is incompatible, it will certainly clump. Observing these reactions will enable the technician to identify a person’s blood form.

Before a perkid have the right to obtain donated blood, the technician will certainly test the reactivity by mixing a sample of the donor’s blood via that of the recipient.