Need more opinions

[Trek Tech]

We had a repeat patient this week. We have transfused him about 4 times over the past year. He has always had a negative antibody screen. He is A Pos (A1). This week my tech gets him, everything looks good; ab screen neg. She pulls two A Pos off the shelf and does an IS xm. One of the units is 4+ incompatible. She repeated it with another segment. Same results. I retyped the unit and the patient and they are both A1 Pos. I did a DAT on the unit and it was negative. I crossmatched the unit with another A patient and it was compatible.

I look in the Technical Manual and it says that most antibodies to low frequency antigens are clinically insignificant. I called my reference lab and they said just use a different unit (Duh!). I do a gel xm with unit and it is 4+ incompatible. (How could this be clinically insignificant?)

I am concerned that this patient will go to the local hospitals which all use electronic crossmatching. We are small and have a low volume so I would never consider doing e-xm. He would be a candidate with his negative antibody screen. Should I give him a card with "Antibody to low frequency antigen"?

Malcolm! I need your expert opinion...I bow to your wisdom!!!!

[L106]

I'm not Malcolm, but I think you are on the right track, Trektech2. As mentioned in one of the other recent threads, it would be a good idea to have some strong wording on the card that you give to the patient (such as "Alert the Transfusion Service before transfusing this patient - Pt has Anti-such&such.")

Donna

[Malcolm Needs ☆]

We had a repeat patient this week. We have transfused him about 4 times over the past year. He has always had a negative antibody screen. He is A Pos (A1). This week my tech gets him, everything looks good; ab screen neg. She pulls two A Pos off the shelf and does an IS xm. One of the units is 4+ incompatible. She repeated it with another segment. Same results. I retyped the unit and the patient and they are both A1 Pos. I did a DAT on the unit and it was negative. I crossmatched the unit with another A patient and it was compatible.

I look in the Technical Manual and it says that most antibodies to low frequency antigens are clinically insignificant. I called my reference lab and they said just use a different unit (Duh!). I do a gel xm with unit and it is 4+ incompatible. (How could this be clinically insignificant?)

I am concerned that this patient will go to the local hospitals which all use electronic crossmatching. We are small and have a low volume so I would never consider doing e-xm. He would be a candidate with his negative antibody screen. Should I give him a card with "Antibody to low frequency antigen"?

Malcolm! I need your expert opinion...I bow to your wisdom!!!!

Hi Trektech2,

I'm extremely flattered by what you wrote, but there are many, many other posters on this site who know at least, if not more than me.

A Wise Ole Saying, "Never mistake my verbosity (with the number of entries that I post on here) for expertise - the two are not the same."

I think that the important word in the Technical Manual is "most".

This is true, but there are plenty of atypical alloantibodies directed against low incidence antigens out there that are most certainly clinically significant. One only has to look in the literature to see that, for example, anti-Wra (of the Diego Blood Group System), is, in many cases clinically insignificant, but in other, rare cases it has caused a severe an immediate haemolytic transfusion reaction.

Although not everyone would agree with me (including some of my own bosses), I think that if a person is either known, or suspected, of having an atypical alloantibody directed against a low incidence antigen in their system, they should not be a candidate for electronic issue, until it is proved that the antibody is benign (and that is very difficult without doing biological assays).

I agree with you that this patient needs a card, albeit, you cannot put a specificity to the antibody.

Actually, to a large extent, that doers not matter, because most individuals who produce such an antibody produce a "soup" of specificities against low incidence antigens.

:):)

[Steven Jeff]

Just playing 'devils advocate' here, whilst being in no position to argue either way in respect as to whether a warning card should be issued. I am a supporter of the electronic cross match (although not a practicing one yet). Trektech2 is absolutely right under electronic cross match rules the patient would have recieved the 'reactive' unit of blood. Would it have done any harm and does it change opinions on whether the electronic cross-match is the way forward from a safety point of view? I remain a supporter of the electronic cross match!!

Steve

;)

[Malcolm Needs ☆]

Just playing 'devils advocate' here, whilst being in no position to argue either way in respect as to whether a warning card should be issued. I am a supporter of the electronic cross match (although not a practicing one yet). Trektech2 is absolutely right under electronic cross match rules the patient would have recieved the 'reactive' unit of blood. Would it have done any harm and does it change opinions on whether the electronic cross-match is the way forward from a safety point of view? I remain a supporter of the electronic cross match!!

Steve

;)

Despite what I have said, I am also a huge supporter of electronic issue of blood, and, yes, I accept that, on rare occasions a patient with an atypical alloantibody directed against a low incidence antigen will be transfused with a unit of blood that is positive for the corresponding antjgen; and it may well cause an immediate, acute transfusion reaction. Such a situation though, would be disappearingly rare.

If, however, we know that a patient has, or is suspected of having, an atypical alloantibody directed against a low incidence antigen, even if the actual specificity is unknown, then I would feel duty bound to carry out a serological cross-match.

I also appreciate that my stance is in line with "what the eyes don't see, the mind doesn't miss"!

:redface::redface::redface:

[David Saikin]

I think the patient has a cold ab. ISxm 4+; gel xm 4+. Could be an M, since gel predisposes . . . was an abid performed? A cold screen/id?

[Eagle Eye]

I agree with David. It could be even anti-P1 oranti-I or non specific cold..

Are you using ProVue to do your screening? ProVue may not pick up some cold antibodies because of 37 C incubation of cards before pipetting.

[Malcolm Needs ☆]

From the way Trektech2 describes the patient history and the cross-match result, I have my doubts.

M+N- true homozygous MM) and P1 strongly reacting cells are not that rare that only one unit would be showing a reaction.

[irshadaad]

why not to go for an antigen profile of the pt. and try to rule out later what possible antibody can play....

[irshadaad]

some times we get screening negative but on running penal we find some of the cells are reactive i guess these things do help to rule out nature of the antibody

[Trek Tech]

I should have said that I did perform a tube panel. Immediate spin and Room Temp was negative with two different panels. Everything was positive at 4 degrees. My reference lab said that there was no reason to send it to them to work it up as it was their opinion was that it was a low freq.

Edited January 25, 2010 by Trek Tech
bad grammar

[Malcolm Needs ☆]

I should have said that I did perform a tube panel. Immediate spin and Room Temp was negative with two different panels. Everything was positive at 4 degrees. My reference lab said that there was no reason to send it to them to work it up as it was their opinion was that it was a low freq.

Ah, in that case, if it was only detectable at 4oC, and not at 37oC, I wouldn't worry about it either.

I thought that you meant that it was reacting at 37oC.

[heathervaught]

To quote Dr. Cox on Scrubs (best...show...ever), "80% of people with pancreatic cancer die within 5 years and 95% of appendectomies occur with zero complications but we both know cases of pancreatic cancer patients that lived and unfortunately appendicitis patients that passed. Statistics mean nothing to the individual" Both manual and electronic crossmatch have limitations -- you are going to transfuse an incompatible unit to a patient eventually. It would just be a different patient under each scenario.

Even with the current system that you describe (negative ABS = IS crossmatch to issue), there are patients with alloantibodies that you will miss because they have an AHG reactive antibody that was not detected with an IS crossmatch.

If you did a root cause analysis, the major underlying issue is that your antibody screen did not pick up that this patient has a potentially clinically significant antibody. And that is to be expected...from the Technical Manual, "A negative antibody screen, however, does not gurantee that the serum or plasma does not have clinically significant red cell antibodies, only that it contains no detectable antibodies that react with the screening cells used or by the techniques used." Bottom line: no technique or system can pick up every single clinically significant antibody. We just commit to do the best that we can with the systems and resources that we have to ensure patient safety.

[AMcCord]

...from the Technical Manual, "A negative antibody screen, however, does not gurantee that the serum or plasma does not have clinically significant red cell antibodies, only that it contains no detectable antibodies that react with the screening cells used or by the techniques used." Bottom line: no technique or system can pick up every single clinically significant antibody. We just commit to do the best that we can with the systems and resources that we have to ensure patient safety.

Well put!

[jhodam]

Your reference lab told you not to send them something because it was low frequency? What's the point of them being a reference lab, then, if not to figure that kind of stuff out? Who is your reference lab, so I know who not to look at the next time I'm going through a job search?

Did you do an AHG crossmatch on the incompatible unit? You mentioned you did an IS crossmatch but no extended workup. If it doesn't react at AHG I would feel better myself about the "low frequency, probably clinically insignificant" label. I wouldn't place too much significance on the cold panel, just because you're seeing positives everywhere doesn't mean that's specific to what's going on with the incompatible crossmatch. Cold reactive "antibodies" are pretty common.

I would find a different reference lab. Even if it is clinically insignificant as it probably is, it's always better for the sake of being thorough (and peace of mind) to nail down a specificity.

[Steven Jeff]

I totally agree with eloquent post made by heathervaught. However, it is my understanding that wiser folk than I have sat down and reported on which antibodies are 'Clinically significant'. Then on that basis we should all be screening against a panel of cells which contain all the clinically significant antibodies. If the screen is positive, we go on to identify and select appropriate cells if required. It is accepted that the screening panels will miss some of the antibodies present in patient’s serum/plasma, but in the main they are considered clinically insignificant.

What is the incidence of clinically significant antibodies being undetected by our screening procedures?

Steve

:confused:

[Malcolm Needs ☆]

Your reference lab told you not to send them something because it was low frequency? What's the point of them being a reference lab, then, if not to figure that kind of stuff out? Who is your reference lab, so I know who not to look at the next time I'm going through a job search?

Did you do an AHG crossmatch on the incompatible unit? You mentioned you did an IS crossmatch but no extended workup. If it doesn't react at AHG I would feel better myself about the "low frequency, probably clinically insignificant" label. I wouldn't place too much significance on the cold panel, just because you're seeing positives everywhere doesn't mean that's specific to what's going on with the incompatible crossmatch. Cold reactive "antibodies" are pretty common.

I would find a different reference lab. Even if it is clinically insignificant as it probably is, it's always better for the sake of being thorough (and peace of mind) to nail down a specificity.

Whilst I think your arguments concerning the ability of a Reference Laboratory to "nail down" the specificity of an atypical alloantibody directed against a low incidence antigen are completely specious, I would defend your right to post them.

Have you, however, any idea whatsoever just how difficult it is to "nail down" such a specificity?

Firstly, you have to have available the red cells that express the antigen (Ol(a), for example, one of the low incidence antigens in the RHAG Blood Group System (RHAG2) has only every been found in one family in Norway) and, of course, they have to be the correct ABO type to identify the antibody specificity in the patient.

Secondly, as I have said before, many saamples of red cells "identified" as, for example, Re(a+) may, in fact, actually be, for example, Li(a+), because the original grouping reagent was either wrongly identified, or contained more than one specificity.

Thirdly, and leading on from point 2, most plasma that contains an atypical alloantibody directed against a low frequency antigen, actually contains a "soup" of specificities directed against low incidence antigens, and so "nailing down" one specificity is usually only the first step on the road.

You may well try to find a different Reference Laboratory, but I will warn you that even the World Health Organisation's International Blood Group Reference Laboratory only rarely does a full work-up on an atypical alloantibody directed against a low incidence antigen.

The Reference Laboratory, like the Hospital Laboratory is there principally to provide an answer to the specificity of rare atypical allontibodies directed against high incidence antigens, and/or the specificities of rare and common atypical antibodies so that blood can be provided to the patient that is, as far s is possible, safe. In the case of a patient with an atypical alloantibody directed against a low incidence antigen, such blood can be easily provided by giving cross-match compatible blood.

If you do decide to go through a job search, and there happens to be a vacancy at my Reference Laboratory, please do not bother to apply, unless you change your attitude.

:angered::angered:

[Malcolm Needs ☆]

I totally agree with eloquent post made by heathervaught. However, it is my understanding that wiser folk than I have sat down and reported on which antibodies are 'Clinically significant'. Then on that basis we should all be screening against a panel of cells which contain all the clinically significant antibodies. If the screen is positive, we go on to identify and select appropriate cells if required. It is accepted that the screening panels will miss some of the antibodies present in patient’s serum/plasma, but in the main they are considered clinically insignificant.

What is the incidence of clinically significant antibodies being undetected by our screening procedures?

Steve

:confused:

Actually Steve, I hate to disillusion you, but it is probably quite high! It would be absolutely impossible to "cover" every antigen on a panel so that all clinically significant antibodies are detected; for one thing, many of the antigens are very rare.

The only thing that one can hope for is that we will "cover" all the more common antigens that are complementary to clinically significant antibodies, taking into account the ethnic mix of both the donor and recipient population. I'm sorry, we couldn't even do it in a reasonable sized panel, let alone on screening cells!

:redface:

[jhodam]

Whoah, Mr. Needs, apparently I was misinterpreted. I wasn't trying to sound like a jerk or anything. I've been spoiled to have the Southern California Region American Red Cross reference lab local, so I'm not accustomed to reference samples being turned away. Sometimes I need to be reminded that such a resource doesn't exist for everyone, and I thank you for bringing that to my attention.

I guess I was trying to remain open in my mind as to what could be going on with an incompatibility detected after seeing a patient specimen for the fifth time. 1/10 units (assuming 2 units per transfusion "event") incompatible is a little different than 1/1000. I'm not sure what your threshold for "low incidence" is, but I was thinking a little lower than 10%. But yes, I assumed a lot and didn't qualify that, so for that I apologize.

It's always intimidating taking that first step into a public forum, especially when one might not express themselves as well as they'd like. It's in writing, so I guess I don't really have an excuse. As for my lack of social graces to begin with, I blame my mother and society. I often find myself paying for my sense of humor (or, as you would probably argue, complete lack thereof). In the future (if I haven't at this point been thoroughly discouraged from further contributing), I'll make sure to read each post at least three times over to keep from posting anything that might be misconstrued as offensive.

Edited January 25, 2010 by jhodam

[Malcolm Needs ☆]

Thanks for that.

PLEASE do not feel thoroughly discouraged. Everyone's opinion is valuable.

[Steven Jeff]

Dear jhodam Please, please do not be discouraged from contributing to the BBT site, Mr Needs (never heard him addressed like that before) Malcolm is a lovely chap and not an 'ogre' at all. If it wasn't for the differences of opnion, discussion, friendly arguement we would not learn anything at all. As for expression in writing, we are all guility of that.

Thanks Malcolm for disillusioning me and I thought things wre so perfect!!! Of course it occurs to me that every time we transfuse red cells to an antbody screen negative patient we potentially risk the stimulation of a clinically significant antibody because we only type for ABO and Rh status. You know I have never checked my own blood after being the recipient of a massive transfusion 5 years ago. hmmmm!!! What I don't know is best some times.

Steve

:)

[Trek Tech]

Ah, in that case, if it was only detectable at 4oC, and not at 37oC, I wouldn't worry about it either.

I thought that you meant that it was reacting at 37oC.

The unit was 4+ incompatible at 37 and at IgG. However, none of the panels reacted at RT, 37 or IgG.

And as far as my reference lab goes, they are absolutely the best! I believe that their response of giving another unit was appropriate. Had I picked up reactivity in the panel I would have insisted on sending it to them.

Well, I guess I got many different opinions which is what I asked for!

Many thanks to all of my colleagues around the world!

[Malcolm Needs ☆]

The unit was 4+ incompatible at 37 and at IgG. However, none of the panels reacted at RT, 37 or IgG.

And as far as my reference lab goes, they are absolutely the best! I believe that their response of giving another unit was appropriate. Had I picked up reactivity in the panel I would have insisted on sending it to them.

Well, I guess I got many different opinions which is what I asked for!

Many thanks to all of my colleagues around the world!

Ah, in that case I WOULD be more concerned about electronic issue. I think that, if we KNOW that there is something there at 37oC, even if we don't know what it is, we are duty bound to perform a serological cross-match, and your idea of issuing a card is excellent.

:)

[TimOz]

Hi Trektech2,

Interesting post. One request of you (any maybe everyone else here). In your originating post it would be very useful to put in a bit more specific technical information in the question. People from all over the world see and participate in this forum so saying "units One of the units is 4+ incompatible" may mean different things to different people. It would be good to tell us the method, the temperature of reactions, the sample type (serum or edta plasma). Most people assume that it would be at 37oC but this may not be the case. This may save some of the misunderstangs of the question.

[jcdayaz]

Ah, in that case, if it was only detectable at 4oC, and not at 37oC, I wouldn't worry about it either.

I thought that you meant that it was reacting at 37oC.

Yep...No need to worry about those 4 degree reactions! A body temp is NEVER 4 degrees (HOPEFULLY)