dumb transfusion question

[Chrismander]

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i apologize in advance for asking a really dumb question, hopefully it's not up there with the glomerulonephritis question--but I can't seem to find anything in my 2nd year books about the effects of giving a blood transfusion that's the wrong Rh-factor.
I'm on surgery right now and for our trauma lecture, we were told the standard when massive hemorrhage is suspected is to give uncrossmatched O positive to men and O neg to women. When we asked why it's different, they said there was no immediate problem giving O-pos to either, but it was just to prevent the development of anti-Rh antibodies in Rh(-) women, to prevent problems carrying Rh(+) fetuses down the line. That part makes sense to me--but I had always thought of O-neg as the universal donor, so why don't they just give O-neg to men *and* women who they don't have time to type? In other words, what's going to happen if your trauma patient is O-negative and you just start infusing O-positive blood? Are Rh-transfusion reactions less severe or something that they're more cavalier about it? Thanks for all your help!
Chris

 

[dermpathlover]

i apologize in advance for asking a really dumb question, hopefully it's not up there with the glomerulonephritis question--but I can't seem to find anything in my 2nd year books about the effects of giving a blood transfusion that's the wrong Rh-factor.
I'm on surgery right now and for our trauma lecture, we were told the standard when massive hemorrhage is suspected is to give uncrossmatched O positive to men and O neg to women. When we asked why it's different, they said there was no immediate problem giving O-pos to either, but it was just to prevent the development of anti-Rh antibodies in Rh(-) women, to prevent problems carrying Rh(+) fetuses down the line. That part makes sense to me--but I had always thought of O-neg as the universal donor, so why don't they just give O-neg to men *and* women who they don't have time to type? In other words, what's going to happen if your trauma patient is O-negative and you just start infusing O-positive blood? Are Rh-transfusion reactions less severe or something that they're more cavalier about it? Thanks for all your help!
Chris

Actually I think they would give O neg to the man also if they had "enough" on the shelf, but giving men and postmenopausal woman O pos isn't that big of a deal.

If you give O-pos to an O-neg person, they will develop an antibody to it over a period of weeks (about 85% of the people will). If they get Rh-pos blood in the future, they will hemolyze it via the spleen over the next couple of days. The reason you should for sure give O-neg blood to women under 45 is they might have a baby and then you are risking fetal hemolysis as the IgG antibodies to the D antigen can cross the placenta. That's the big deal with Opos vs Oneg (avoiding potential HDN).



There isn't risk of life threatening hemolysis like with anti-A, anti-B, anti-H (for Bombays). The naturally occuring antibodies are IgM which bind and activate complement resulting in intravascular hemolysis, DIC and risk of renal failure and death.

 

[yaah]

The reason they give O- in a massive transfusion situation is that oftentimes there is a shortage of it (at least relative to O+).

Second, in a massive transfusion situation oftentimes the transfused blood does not stay in the patient that long (because they are continuously losing blood), thus the transfused cells might not be in their body long enough or in sufficient quantity to make antibodies to Rh antigens (whereas, as said above, anti-A, B, whatever are already formed and would cause instant hemolysis). This happens very frequently in liver transplant patients (an A- person getting transfused with A+, for example) because they often use dozens of units during surgery. The appropriate units (the A-) will be saved until the patient is in the clear surgically and the units are likely to stay in their system.

In women of child bearing age, it isn't worth the risk. But for men and older women, it can be, because the last thing a transfusion service wants is to run out of O- blood.

Patients who need 1-2 units will always get compatible units.

 

[dermpathlover]

i apologize in advance for asking a really dumb question, hopefully it's not up there with the glomerulonephritis question--but I can't seem to find anything in my 2nd year books about the effects of giving a blood transfusion that's the wrong Rh-factor.
I'm on surgery right now and for our trauma lecture, we were told the standard when massive hemorrhage is suspected is to give uncrossmatched O positive to men and O neg to women. When we asked why it's different, they said there was no immediate problem giving O-pos to either, but it was just to prevent the development of anti-Rh antibodies in Rh(-) women, to prevent problems carrying Rh(+) fetuses down the line. That part makes sense to me--but I had always thought of O-neg as the universal donor, so why don't they just give O-neg to men *and* women who they don't have time to type? In other words, what's going to happen if your trauma patient is O-negative and you just start infusing O-positive blood? Are Rh-transfusion reactions less severe or something that they're more cavalier about it? Thanks for all your help!
Chris

I just read your question again. You pretty much have it all figured out. Yes "Rh-transfusion" reactions and most all reactions to other blood antigens are less severe. It all has to do with the fact that anti-A and anti-B bind and activate complement.

 

[LADoc00]

There are no dumb questions, only dumb pathologists.
-Towelie

 

[Anna Plastic]

I have to strongly disagree with the opinion that only ABO group antigens (including H) are involved in life-threatening hemolytic transfusion reactions. RhD + blood given to a previously-sensitized RhD negative patient bears a significant risk of acute hemolysis which can result in DIC or renal failure. I've seen "acute" hemolytic reactions to patients who have been sensitized to Duffy, Rh antigens, and others--all usually associated with delayed hemolytic reactions. The idea of ABO = acute hemolysis and all other antigens = delayed hemolysis isn't quite accurate. It's better to think of it as intravascular and extravascular (as was raised in this discussion). Intravascular hemolysis is most associated with IgM molecules formed to carbohydrate antigens (such as ABO), as they are the most efficient at activating complement. But when you are dealing with antigens which are as dense on the surface as Rh antigens are, you can get intravascular hemolysis as well (Rh, being a protein antigen, is most likely to have IgG formed).

Its all a number game. Because it is so antigenic, and because of its association with hemolytic disease of the newborn, we try to protect women from Rh sensitization for this reason. But that doesn't mean it is a clinically trivial risk for men or post-menopausal women either. When we don't have time for proper blood typing and cross-matching, as in trauma, we have to give what we feel poses the least risk to the patient. Usually this means O negative blood, but if our inventory is short or limited, we will give O positive blood to men and post-menopausal women. Be very clear that this poses some risk (albeit small) for acute hemolysis for the recipient, but it is the most balanced option we have in preserving the blood supply for the entire community. (In my city, we're lucky. Our blood supply lets us start with O neg for all trauma patients, and we will switch the men and older women if it looks like they will be using a lot and we are low). Almost always this won't be a problem. But be aware that if you start getting cherry Kool-Aid from your patient's Foley 'round about the time their pressure starts tanking, you may be looking at hemolysis.

I'm rambling some here, but seeing someone say ""Rh-transfusion" reactions and most all reactions to other blood antigens are less severe" just stuns me. This is flat out wrong. Hell, people receiving RhoGam for ITP treatment have wound up with acute hemoglobinuria and DIC. Clearly, anti-RhD can be very dangerous.

Chrismander, it wasn't a dumb question at all. Even pathologists (and pathologists in training) aren't entirely clear on these points, as you can see.

By the way guys, just got back from vacay today, and got my AP/CP boards "congrats you passed" letter. As I promised back in June, my study approach will be posted shortly for anyone who is interested.

 

[yaah]

No, I think people are clear that these can be very bad transfusion reactions - "kidd kills" etc etc. They are just less likely to be severe whereas ABO is instantaneous and devastating. Thus, the risk is taken. The OP was asking this question and we were giving our opinion as to why. I think any resident knows that Rh antibodies can be dangerous - that's precisely why we avoid transfusing people with them.

 

[Anna Plastic]

My reply wasn't directed at you, yaah. Rather at our friend who hold TM in some scorn, but states "There isn't risk of life threatening hemolysis like with anti-A, anti-B, anti-H (for Bombays)." There *is* risk of life-threatening hemolysis. I agree that ABO reactivity is brisk and severe, but it can be more delayed sometimes; converesly, Rh reactivity can sometimes be as brisk and severe. The risk is taken not only because of the nature of the reaction, but because almost everybody has anti-ABO naturally formed, while you need previous exposure to Rh positive blood in order to have anti-Rh. Your patient is therefore much less likely to have a hemolytic reaction to Rh as compared to ABO.

 

[yaah]

Well, in his defense Blood Bank is a zero star fellowship.

 

[djmd]

The risk is taken not only because of the nature of the reaction, but because almost everybody has anti-ABO naturally formed, while you need previous exposure to Rh positive blood in order to have anti-Rh. Your patient is therefore much less likely to have a hemolytic reaction to Rh as compared to ABO.

Thats what I was going to say, in a trauma on can act with the baseline of assumed no Rh antigen exposure.

Of course in, MASSIVE tranfusions (liver transplants and the like) at some point it no longer matters at all what blood type you are giving. You give enough Red Cells, FFP and the patients volume is no longer his own, and if it is just pouring out the other end...

 

[dermpathlover]

Your patient is therefore much less likely to have a hemolytic reaction to Rh as compared to ABO.

Bull****. He is guaranteed to have a hemolytic reaction provided he was sensitized. The difference is that it will be "extravascular" vs "intravascular"

And I said "most all reacitions are much less severe than anti-A, anti-B and anti-H" And that is soooo the truth.

How often does anti-D result in intravascular hemolysis, DIC and death? I would guess it to be so rare that you could say almost never.

And if I had a patient who was bleeding to death and had a D-antibody but I only had one bag of blood in the whole band and it was RH +. I would have no problem giving him that bag. However, if he was type A and bleeding to death, I would not give him a type B if it was the only bag left.

Give me a break. That's why it is OK to give old women and men O+ blood during O- shortages. Because, while it is less than ideal to be sensitized to the D antigen, extravascular hemolysis isn't that big of deal and can be managed by watchful physicians, unlike intravascular hemolysis where the patient can go down the tubes even with every doctor and nurse in the hospital doing all they can to save him.

 

[Cabbage Head]

There isn't risk of life threatening hemolysis like with anti-A, anti-B, anti-H (for Bombays).

?

 

[Anna Plastic]

Bull****. He is guaranteed to have a hemolytic reaction provided he was sensitized. The difference is that it will be "extravascular" vs "intravascular"

And I said "most all reacitions are much less severe than anti-A, anti-B and anti-H" And that is soooo the truth.

How often does anti-D result in intravascular hemolysis, DIC and death? I would guess it to be so rare that you could say almost never.

And if I had a patient who was bleeding to death and had a D-antibody but I only had one bag of blood in the whole band and it was RH +. I would have no problem giving him that bag. However, if he was type A and bleeding to death, I would not give him a type B if it was the only bag left.

Give me a break. That's why it is OK to give old women and men O+ blood during O- shortages. Because, while it is less than ideal to be sensitized to the D antigen, extravascular hemolysis isn't that big of deal and can be managed by watchful physicians, unlike intravascular hemolysis where the patient can go down the tubes even with every doctor and nurse in the hospital doing all they can to save him.

I'm about as weary of this thread as anyone, but I wanted to point any interested parties to Popovsky's "Transfusion Reactions" so they can read for themselves on acute hemolytic transfusion reactions as related to different antigen-antibody specificities. Antibodies against RhD can cause severe, potentially life-threatening acute intravascular hemolysis, despite what dermpathlover is saying here.