In elementary school I remember I was taught that O can be a donor to all blood types, and AB can receive transfusion from any type. However, in third world countries there’s often mass messages such as “Urgent: my relative who’s in an emergency situation need an AB donor”. How come?
Perhaps because they are AB negative. AB positive is the universal acceptor.
I have no idea where you got the impression that this message is frequent anywhere. IANAD, but from my layperson’s reading an AB+ person can receive any ABO blood type. Any person who’s Rh negative must receive Rh negative. Someone who’s O- is the universal donor. That’s why in life-or-death emergencies without time for blood typing they give O Neg.
You are correct that an AB type can get blood from any other type (notwithstanding Rh group and other crossmatching details).
I cannot speak to “third world” mass messaging, but I’ve seen many a hackneyed Hollywood over wrought and inaccurate tension building devises that posit the saving of the day on the improbable appearance of a blood donor compatible with someone’s so-and-so who has the “misfortune” of being endowed with that very rare blood type, AB.
In that case, it’s obvious the writer just looked up the frequency of types, and had no understanding of how it works.
I see… Is there an authoritative reference on the net that I can show people, that showed that O to other blood types transfusion are regularly done and not just possible in theory?
Why does it say only " in an emergency or special circumstance"? Why not in any circumstances? And how bad the situation must be for this to be considered?
If the third world was Asia, then they have nearly no Rhesus negatives… perhaps the request was for donations from negative type…
Probably because those types are comparatively rare, so they don’t want to use them up unless they absolutely have to – like in an emergency. Basically a supply-and-demand issue.
Back when I worked in the NHS, it was generally accepted that a trauma patient only really needed some suitable liquid in their system to keep the organs going. Saline was used to replace lost blood until the leak was repaired and whole blood given.
As an aside - over here, all blood donations are entirely voluntary, and the only reward is a cup of tea and a biscuit (cookie). And, of course, the glow that comes from helping one’s fellow humans.
RH factor is a bit more complicated. An RH negative person can be safely given RH positive blood… once. It takes one exposure before the body builds up the antibodies that make it dangerous. On the bad side, though, the RH factor can also cross over the placenta between a mother and fetus, so if the fetus is RH positive, the mother becomes exposed, which can cause serious problems in subsequent pregnancies. This is one of the things they test for in pre-marriage blood tests.
Ideally, blood to be transfused is not only typed, but cross-matched between the blood to be transfused and a sample of the patient’s blood in a lab setting to make as sure as possible that no incompatibilities exist.
The ABO/Rh blood typing system lets us predict major incompatibilities which, if they exist, can result in massive hemolysis (breakdown) of the blood being transfused, along with other things that trigger potentially lethal transfusion reactions.
Typing and cross-matching blood takes time. Occasionally, patients are bleeding out so fast that there isn’t time, in which case we’ll give O negative (Neither A nor B antigen, and Rh negative) blood. This is the least likely commonly available blood to have major hemolysis, because without those antigens, even if the recipient has A, B or Rh antibodies, there won’t be any antigens on the transfused blood for those antibodies to react with, and so there’s less chance of a major hemolytic transfusion reaction.
This is all vastly oversimplified for a quick post.
I would say as I think back over my medical career that I’ve only given O neg in a handful of cases–things like major trauma bleeds, portal hypertension bleeds, and the like. Modern labs can type and cross match quite rapidly, so the risk of waiting a few minutes is almost always worth it. Transfusion reactions occur for many reasons beyond ABO Rh incompatibility, and it’s distressing to kill a patient with the wrong blood.
In addition, there’s a whole brouhaha with any modern lab about them sending up un-cross-matched blood. Signatures; phone calls; Director conversations…you get it. By the time all that’s done, lo and behold the cross-matched blood is ready… 
Beside the blood groups, I wonder if the * antibodies * in the blood of Patient A and Patient B can be mutually incompatible…
I think it’s highly unlikely that one person’s antibodies would mistake another person’s antibodies for antigens. A lock will not mistake another lock for a key.
Are you contrasting that with someplace that compensates people for mandatory blood donations? Where does that happen?
Actually, anti-Ig antibodies are used routinely in the lab for immunofluoresence and other experiments. The constant region of antibody molecules can be used as antigens.
However, that’s one species recognizing another species. Human antibodies should all be pretty much the same from individual to individual.
Perhaps… according to Isaac Asimov, everyone has his/her own collection.
Yeah, I did similar experiments back in college, using limpet antibody proteins as an antigen in BALB-C mice. But you’ve got to have creatures pretty far apart, different families at least, if not different orders. Not in the same species, except by very bizarre chance.
I think.
Or perhaps he’s thinking of plasma, whose donors can be compensated in the U.S.
But in the U.S., whole blood donors cannot be paid for donating, although I got a T-shirt last month when I donated.
And they also wanted to enter me in a drawing to win a 4-wheel ATV. I declined, as I don’t want to win such a vehicle.
The majority of pre-marriage blood test were looking for syphilis and Rubella. I don’t think any states require blood tests anymore and, even when they were required, they were mainly for detecting STD’s…not Rh compatibility