Friday, February 20, 2015

Study group discussion: Blood group doubts

Can a person with blood group
AB -ve be given A -ve and B -ve?


AB blood group people are universal acceptors. Of course, you can give.

The problem of Rh negative is important when it is a woman. You can't give a Rh positive blood to an Rh negative female.

Is it because of any future pregnancies or something else?

The Rh negative woman will develop antibodies against Rh positive blood groups.

In successive pregnancy there's risk of erythroblastosis fetalis.

But isn't it also bad to give Rh + blood to anyone who is Rh -? I've heard you can't give positive blood to a negative male too.. Because of the tranfusion reaction following it na?

The important difference here is unlike the AB blood groups..
A patient who is of B blood group..He is missing the a antigen on the cell. Therefore, he has the a antibody in the plasma. But if the patient is Rh negative..He won't have the corresponding antibody.

And if that person is given rh+ blood won't their body produce anti D antibodies? Since D is an antigen?

A Rh negative person will only form antibodies when exposed to RBC which are Rh positive.

So even in males antibodies will be formed. And haemolysis and consequent reactions will be there?


So it shouldn't be preferable to give Rh + blood to anyone who is Rh - regardless of gender.


Yes! Therefore, we ask for previous blood transfusions.

But in cases of emergency. You first go for O negative blood. If not available.. Even of positive can be used.

So if we would have to do a list
1. O Rh negative
2. O Rh positive

But especially in cases of women.. You have to be super cautious not to use a positive blood group if she is a negative.

You have a patient with A rh- blood who is in need of urgent transfusion. And you have two possible donors: An O Rh -  person and a A Rh + person. Which one do you choose?

O negative.

You can't give positive to a negative person!

Yeah since its a universal donor. And the Rh is same.

But O negative blood is reserved for emergencies..So it depends on the availability. If you manage to get hole of the same A+ for an A+ That one is preferred

You preserve O - cause in emergencies there is hardly any time for blood group testing

Fair enough.

Treat positive as an antigen. You don't wanna create unnecessary antibodies in anyone because it increases the risk of organ rejection in the future. So regardless of the sex, you wanna properly match the blood.

Also future blood transfusions can be an issue.. Due to undue antibodies.

If you have no choice which antigen is worse the Rh, or the blood group?

The blood group.

They will cause an immediate reaction which is fatal.

Okay thanks! :)

As I said antibodies to Rh are not preformed.. They take time to form.

Oh I wasn't aware of that distinction. Thanks again.

Got a question. Would the anti A and anti B in O group prove antigenic to the patient? Of course, if he is either B or A respectively or AB

You mean to ask If the antibodies against A and B of O donor, will effect A B and AB recipient?

Yes, exactly.

No, I guess..

But why?

I think they are not in a significant quantity.

Because they are not yet exposed to A and B antigen when they were in donor.

In contrast, if mismatch occurs, the patient's body will produce numerous antibodies against the donor blood.

If I were to guess, I'd say once they leave their own system (the donor) they lose ability to mature into active antibodies.

They are not really viable ones the blood is collected from the donor. However we still have minor cross matching for that.

We had a discussion on that before!

Here it is:
O negative blood group


The discussion is good. Thanks!


  1. Here's my burning immunohematology question: If all people who are type A (AO or AA) naturally produce anti-B without prior exposure, and all people who are type B naturally produce anti-A without prior exposure, why isn't the AB blood type a fatal genetic combination? Why doesn't the A cause them to produce anti-B and why doesn't the B cause they to produce anti-A?

    1. You don't produce these antibodies naturally, you produce them after exposure to antigens in the environment (mostly food).


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