Recently, a very astute reader by the name of David wrote to me regarding my latest novel Fractured Memory.

In the letter he writes:

“On page 67, you referred to a child with ‘the most rare blood type–AB negative.’ You then implied that to give a transfusion to the child, AB negative blood would be required. As far as blood type is concerned, it was my understanding that AB negative is close to being the Universal Recipient (which would actually be AB positive). Thus, while AB- may be extremely rare, such a person could still accept blood which is AB-, A-, B- or O-, so the rarity of AB- itself doesn’t necessarily mean it would be difficult to find donor blood for a transfusion.”

Strong work, David, strong work.

With a couple of caveats.

Why do we even worry about blood types and who can accept whose blood? The issue comes down to whether or not your body will identify the donated blood as a foreign tissue or not. If the body looks at those newly infused blood cells and cries out in terror because it doesn’t recognize it as self— it mounts a war on a cellular level to kill those foreign red blood cells, which leads to a drastic systemic reaction that can lead to some very serious complications for patients.

The trick in transfusing blood is to give something the body doesn’t recognize as foreign. The letters in your blood signify antigens but also signify which type of antibodies are in the blood. So a person who is blood type A has B antibodies in their blood which means if they get any blood with a “B” in it (B or AB), that person’s body is going to want to kill those blood cells. People who are blood type “O” carry antibodies to both A and B blood. Therefore, a person with type O blood can only receive type O blood.

So, yes, a person who is AB negative can safely receive blood from a person who is A-, B-, AB-, and O negative. But for the purposes of a planned surgery, which was the case in the novel, usually type specific blood is sought out. Also, the other blood types this patient could receive are about ten percent of the population combined. Individually they number a lot less. Certainly not impossible to find depending on what’s in stock in the blood bank. Because O negative blood is so valuable in the sense that anyone can receive it it is generally reserved for emergency situations and would likely not be used for a planned surgery.

This article is a great resource for writers when it comes to blood types and who can get whose blood.

Do you know how a person’s blood type is determined?