Is O-type blood "universal blood"? Can it be transfused at will? Don't be fooled again...

Expert of this article: Yan Kaixin, Master of Cardiology, PLA General Hospital

This article was reviewed by Zhang Mingzhi, a postdoctoral fellow at the Fuwai Hospital of the Chinese Academy of Medical Sciences

With the popularization of medical knowledge, we all have a certain understanding of blood types.

Most people believe that blood types are mainly divided into 4 types: A, B, AB, and O. People with AB blood type can receive any type of blood, while O blood type can be given to anyone.

But this idea is rather one-sided.

Today we will talk about blood transfusion.

Who in history

Who was the first to give blood transfusions to humans?

In ancient Egypt, blood was considered to have magical powers, so kings and nobles often used the blood of captives to wash their bodies in an attempt to drive away diseases and maintain health.

When Pope VIII was critically ill and in a coma, his doctor suggested drinking blood to save his life. The ministers killed three healthy men in a row and made the Pope drink their blood. As a result, the Pope also died.

Since then, there have been cases where a blood transfusion was successfully given to a general who was bleeding using a reed tube, and there have also been cases where a man with a bad temper died after a sheep's blood, which was considered to have a "gentle character", was transfused to him. All of these are bold attempts in the history of blood transfusion.

It was not until the 1880s that British obstetrician and gynecologist Blundell first attempted human-to-human blood transfusion to save patients with severe bleeding. From then on, blood transfusion gradually became a regular treatment option.

What are the blood type requirements for blood transfusion?

Human blood types are generally divided into ABO blood types and Rh blood types.

(1) ABO blood types are divided into: A, B, AB, and O.

ABO blood types are named according to the names of antigens:

If there is A antigen in the red blood cells, it is called type A blood;

If there is B antigen in the red blood cells, it is called type B blood;

Containing both A and B antigens is called AB type blood;

Blood type O contains neither A nor B antigen.

Blood transfusion is certainly not a random one. The transfusion requirements must be strictly followed: transfuse blood of the same type.

Normally, people with type A blood receive type A blood, and people with type B blood receive type B blood. If other types of blood are used, it will cause a transfusion reaction.

(2) Rh blood types are divided into Rh negative blood and Rh positive blood, expressed as Rh (-) and Rh (+).

Although ABO and Rh are different types, they are a case of "you are in me and I am in you".

Rh blood type is classified according to the presence or absence of D antigen on the red blood cell membrane (with D antigen, it is Rh positive; without D antigen, it is Rh negative).

Among the ABO blood types, taking type A blood as an example: blood type A contains A antigen, and if there is also D antigen, it is type A blood + Rh positive blood.

The principle of Rh blood transfusion is to transfuse blood of the same type, that is, Rh negative people can only receive Rh negative blood.

Regardless of the blood type, ABO and Rh blood type cross-checks must be performed before transfusion. Once the wrong blood type is transfused, it will cause transfusion reactions such as chills, high fever, nausea, vomiting, etc., and in severe cases it can be fatal.

What are universal blood and panda blood?

In daily life, when people refer to "universal blood", they are referring to type O blood.

The reason why type O blood is considered "universal blood" is that there are no A or B antigens on the red blood cells of type O blood. When type O red blood cells are transfused to patients with type A, B, or AB blood, they can provide emergency treatment. Therefore, in clinical practice, "washed red blood cells" of type O blood are often used to transfuse blood to patients with type A, B, or AB blood.

However, this concept is extremely incorrect. In fact, "universal blood" is not "universal" and is very dangerous.

O-type blood plasma contains anti-A and anti-B antibodies. Once O-type blood plasma is transfused into the body of A, B, or AB blood type patients, an agglutination reaction will occur immediately, causing severe damage to the recipient's red blood cells and leading to hemolysis.

Therefore, it is prohibited to transfuse O-type blood plasma to recipients of other blood types.

Some people also say that people with AB blood type are "universal blood recipients." This statement is not rigorous, as current clinical blood transfusions are all of the same blood type.

"Panda blood" refers to people with Rh negative blood type. Because 99.7% of people in my country have Rh positive blood, the rare Rh negative blood is called "panda blood".

Neonatal Rh hemolysis is a hemolytic disease caused by the incompatibility of the mother's and fetus' blood types. If either parent has "panda blood", they should receive medical guidance before pregnancy to prevent neonatal hemolysis.

In what situations is a blood transfusion necessary?

Blood transfusion usually refers to the infusion of blood into the patient's body through the vein, and is widely used in clinical practice. Blood transfusion generally refers to blood components: suspended red blood cells, concentrated red blood cells, leukocyte-poor red blood cells, washed red blood cells, fresh frozen plasma, platelets, cryoprecipitate, albumin, etc.

However, not all patients can receive blood transfusions. Blood transfusions also require indications:

1. Patients with acute massive bleeding should be given blood transfusion immediately to prevent shock, such as open massive bleeding caused by trauma or internal bleeding.

2. Patients with severe anemia, such as blood diseases and poor hematopoietic ability, should first receive blood transfusion treatment and then undergo follow-up examinations.

3. For patients who are expected to bleed heavily during surgery, blood should generally be prepared before surgery to prevent excessive blood loss during surgery.

4. For chronic anemia with hypoxia symptoms, red blood cell transfusion may be considered when hemoglobin is <60g/L or hematocrit is <0.2.

In short, blood type cross-check must be done before blood transfusion, and blood of the same type must be transfused; choose the appropriate blood transfusion method (component blood or plasma) according to the specific circumstances of different patients, pay attention to the transfusion speed, and pay close attention to whether the recipient has any adverse reactions to the transfusion. If an adverse reaction occurs, the transfusion must be stopped immediately for treatment.

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