Polite Dissent

Black Adam #4 “The Dark Age, part 4″
Peter Tomasi, writer
Doug Mahnke, penciler

Wounded by gunfire, Black Adam arrives in a veterinary clinic and demands that the doctor and her assistant treat his wounds. As part of his treatment, Adam required a blood transfusion, so both the doctor and her assistant donate their own blood.

Doctor: Relax. You’ve been out for over 2 hours.
Adam: Two hours?
Doctor: And I’d appreciate it if you waited till you left to pop open all my sutures, ’cause we’re all out of blood.
Adam: Whose blood?
Doctor: Luckily for you — and us — you’re an O positive. My assistant and I did what we needed to do.

There are two ways of interpreting what the doctor has said:

1. Black Adam and the doctor and her assistant are all O+. This is the only explanation that actually works, but I don’t think it’s what the author had in mind. First, it’s statistically unlikely. While O positive is the most common blood type, the chance for three random people to all have it is only 5%.¹ Second, the conversation doesn’t really support this interpretation. The doctor specifically says Adam has O+, not “luckily we were all O+“.

OR

2. The doctor (and the author) have a misunderstanding of type O blood as it relates to transfusions. They are confusing “universal donor” with “universal recipient.” If this interpretation is correct, the doctor is making a couple of mistakes:
First, O negative is the universal donor, not O+. Second, Black Adam is receiving blood, not donating, and an entirely different set of rules apply. There is an inverse relationship between donating and receiving. Blood types that are good for donations are poor recipients, and vice versa. For instance, AB+ can only donate to other AB+, but they can receive blood from any blood type (they are the “universal recipient”); conversely, O-, the “universal donor”, can only receive other O- blood. When Black Adam develops a transfusion reaction, we’ll know why.

To add one final wrinkle, if you read the comic, you’ll notice that Black Adam has received a whole blood transfusion (which is extremely rare in real world medicine. Usually only red blood cells are used). This means that not only are red blood cells transfused, but plasma as well. So not only do you have to worry about Adam’s plasma reacting with the donated red blood cells, but you also have to worry about the donated plasma reacting with Adam’s red blood cells. In this case, he should only receive a transfusion from an identical blood type — which in a roundabout way brings us back to the first answer.⁴

Other Comic Book Transfusions

Notes:
¹I’m going with the distribution of O+ in the US population (38%). Obviously, this wouldn’t apply to Black Adam, but I’ve yet to find any reliable data on the distribution of Quraci blood types, let alone Quraci blood types from a millennium ago — and 38% seems to be a good median value.
²Technically they’re glycoproteins (a structure composed of proteins and sugar molecules), not just proteins, but I’m trying to keep it as simple as possible (though that seems to be a moot point now. For more information, Wikipedia has quite a good explanation of blood types and transfusions).
³I have not mentioned the Rhesus factor (Rh, the positive or negative part of the blood type) yet because it is a little more confusing. Red-blood-cell-wise, it works in the same manner as the ABO blood types. People with a positive blood type have the Rh protein on the surface of their blood cells while those with negative blood type lack this protein. However, there is a slight difference when it comes to the plasma. Unlike the ABO blood types, people with Rh-negative blood will not generally develop anti-Rh antibodies unless they’ve been exposed to Rh-positive blood (generally from a previous transfusion or childbirth).
⁴None of this answers the key question of why a veterinarian has the proper supplies to type human blood.