rravkin@aol.com

If need be perform K/B testing to determine the number of RHIG vials needed.

I just wanted to post a correction to my most previous post where I state that the ABO/Rh typing card is performed as an immediate spin reading. It is actually spun the same time that the ABSC card is spun by program and therefore it incubates for approximately 10 mins at RT, close enough to the 15min RT inc performed with the ABO discrepancy workup. The fact that this card incubates at room temp for 10min would help increase reactivity forward and back and therefore lend to the idea that if the backtype comes up weakly reactive then, dare I claim that, it is possible that a false neg ABSC may occur. This is based on the idea that a patient with a healthy immune system will readily produce ABO antibodies incuring a strong reaction with our testing method and if that reaction is weak then one possibility is that the concentration of ABO antibodies is decreased do to lack of production and therefore any allogeneic antibody production would also be diminished such that it will not be detected with our ABSC method. Just some food for thought; lets not get crazy now.

How do chemotherapy transfusionists keep their patients seated for 3 to 4 hours at a time?? I think maybe we can apply the same practices here. It is an incredible safety issue for all involved.

Have you checked with the manufacture to see if you can spray the ball barings that the tracking of the draw slide on, with any lubricant, such as WD-40? If allowed I would try this. Also, splashing that you see can equate to cross-contamination of the wells and therefore should try to be avoided.

We run our eluates in Gel as well and aside from the problem with the junk we also make extra sure the pH is where it is supposed to be; we use an acid elution kit.

To all who posted here, I just wanted to thank you all for your input. Although it was somewhat of a rough ride I walk away with a much better understanding of what we do and the limitations that exist in our techniques. I only was trying to inspire the kind of post that I eventually got from John Eggington. I in no way was trying to speak of changing our whole routine or instrututing any significant change there of and I really do not know how we managed down that path in the first place as I did state earlier in this thread. As far as the " strange way of thinking" from Abdulhameed, if you are refering to the fact that the backtype performed on the ProVue is not incubated and the ABSC is I can see where you would think this logic to be strange given that the incubation phase of the ABSC would greatly enhance reactivity over the virtual imediate spin of the backtype on the same instrument. It would be nice to further explain such remarks in the future as they may be misunderstood. I have done some resarch on Delayed Hemolytic Transfusion Reactions since starting this thread and I come to find that they can be every bit as severe as an Acute Reaction and therefore every bit as detrimental to our patients. I think it is important to maintain a back-up technique that is available if and when needed. Thank you all again.

Thank you John, I greatly appreciate this post.

Oh dear, John, don't get your nickers in a bunch!

We use a 15Gy indicator placed at the top of the bag.

Well John, thank you for sharing with us your insight. This is why we all joined PathLab Talk so that we can benefit from the wealth of knowledge and experience from interesting and insightful professionals like yourself.

Thank you John. I guess I wanted to know the details of the "Bag of Tricks."

David, Thank you for your honest post. You are right, it is entirely possible that a mountain is potentially being made of a mole-hill but when the backtype enhancements are tried and do not enhance the reaction and the patient does not fall into the usual category of an immune-suppressed patient and there is no responsible history attainable for this patient, do we just kiss it up to God and hope for the best or should we be aa little more proactive?

Veejay, Thank you for your post but I think that the tube test also relys on Brownian Motion to for the reaction to occur. We may not think of it this way bause it is an immediate spin procedure and therefore there is little delay between combining reactants and centrifugation. Here the centrifugation will concentrate the cells which have already adsorbed the anti A1 and /or B respectively. When we are working up a descrepancy that occurs in the backtype we increase centrifugation time, which may lend to your theory, but we also increase incubation times at RT, 37C, and 4C.

AMcCord, Thank you for your detailed post. I appreciate the last pargraph specifically. If you don't mind explaining, I was wondering what additional work do you do to resolve a consistantly weak backtype? Thank you again.

John, I use the term "immunesuppressed" to mean that there is a weak conncentration of ABO Ab and/or alloAb. But you have stated the precise reason for any extended work with a weak backtype, "immunocompromised." This is exactly what we can not understand from our testing methods, if there is indeed a compromise at all; nor can we fully understand the length of the condition either, will it last a few hours,days,weeks, or months. To go and extrapolate this reasoning to all patients irregardless of backtype reactivity is to say that our testing systems are completely invalid, and this is just not true. As far as missing a weak antibody in an immune competant patient, I would ask how are you judging immune competance; certainly not completely by our testing methods, you are also looking at patient history, and current condition and making a judgement call on the relative immune competance of this patient. If your backtype gives strong reactivity why would you even question the immunecompetancy; however if the backtype gives weak reactivity then there is ample reason to question the immunecompetancy because you a tangible results pointing towards immunesuppression; which, as I stated earlier, may not be the only reason, but to produce the better compatible product for this patient we should test on the side of caution.

I wonder if this is a new Anti E and the concentrations of IgM and IgG fractions are somehow involved in these reactions.

John, Certainly the enhanced technique can be used for other patients but I would think that this would be a judgement call and not a routine occurence. And if David hadn't got a valid ABO result he would be performing a further workup to investigate an apparent ABO discrepancy not simply an extended crossmatch.

We use an automated system for our type and screen testing but all crosmatches are done in tube including extended crossmatch which is done at all phases. I can see that my blood bank suppervisor is concerned with Anti-M and like antibodies, and I appreciate her insight as well as this thread. Thank you SABarry.

John, Jayinsat, and Mable, It is obvious that our testing sytems will not offer any alert for an AB patient. However, for all the rest of our patients in general a strong reacting backtype is the norm and a weak backtype is the rare occurence. David's practice at least acknowledges the possibility of a missed alloAb. From the practicle standpoint the extended testing that I've suggested is highly do-able and would not cost but a minimum in extra materials for the general population because this occurence is so rare; the only real extra cost is maybe time. Given that the ABO antibodies are the first to develope and remain strong for the most part through the course of life based on our own testing and that any detected alloAb's more often show weaker reactivity it stands to reason that our testing systems may not detect an alloAb if the backtype is weak. Although our testing methods have come a long way and offer greater levels of compatibility there are still some limitations. No one using our testing methods could definitively determine the cause of a weak backtype; but we all know that the worst error that can occur in the blood bank is the reporting of a false negative result; our antibody screen. Therefore, I was suggesting a relatively simple method to further testing to ensure that we do not miss a weakened alloAb, which as of the present poses no indication of an acute response but like we don't know the cause of the weak backtype we also don't know if or when the patient's immune system is going to start working at normal capacity either. Immagine if we actually detected an alloAb and if the patient needed red cells then we would be able to provide a more compatible product. Isn't that what blood banks do; provide compatible products. So why are we not addressing this limitation in our testing systems so that we can produce a better compatible product? This is what we do, I think.

Testing Post

Yes, that is exactly why but I was not suggesting an elution. I would use multiple absorbtion in order to capture enough antibody to be detected by IgG.

Mable, You are correct about the 40 min time maximum for the Gel Card incubation at 37C as I found out the other night. I did neglect to mention the reagent red cells for which to crossmatch our specimen within my long post. I would naturaly use Rh positive reagent red cells for the control and I would use a selected cell panel for my patient specimen where each of the antigens would be represented homozygously. The rarity of this occurence outside of cancer, transplant, elderly, and infant populations is such that the line of testing I proposed would be feasable; even with two adsorbtions. Consider that the control antisera is either premaid or can be made up as needed once the dilution is clarified and as far as the panel cells are concerned one could easily estable the battery of cells with each new lot of panel cells. We would then be practicing incubation for one hour at 37C for each adsorbtion; a very easy procedure to work into performing other testing.

Mable and Galvania, I did not want to debate the means of investigation, however last I read the package insert of the Ortho Gel Card it stated that gel integrity started to be lost after 30min 37C incubation. I was trying to point out the fact that a weak backtype suggests a immune suppression and that an alloAb may be missed unless an extended workup is performed. What we are trying to prevent, or at least be aware of, is the anamnestic response which has been implimented in patient morbidity albeit, rarely. The families of Ab's associated are the Rh, Kell, Kidd, and Duffy systems. It seems that from the responses I've recieved here, there is no one performing any additional testing when a weak backtype occurs. Perhaps, any adverse occurence whoes only symptom is a weak backtype is so rare that it is not worth the resources to investigate.

[quote=rravk Galvania, an Acute Hemolytic Reaction is unlikely but we do not know if a delayed reaction can occur nor can we know the severity.

Galvania, I am glad you asked. First off "Why"? When you hav eweak backtype then one reason for the is low concentration of ABO antibodies. One reason for this low concentration is Immune Suppression. Now , the ABO antibodies are some of the first antibodies (if not the first) produced by the immune system three months approximately after birth. The immune system then maintains throughout life a high enough concentration such that we reutinely see no less then a 3 to 4 plus reaction when performing our backtype. The immune system does not always and in every case treat the allogenaic antibodies quite the same way. Often time concentrations in the plasma are less than that of the ABO antibodies. So if your backtype reveals a decreased concentration of ABO antibodies then your allogenaic antibody concentration has a high probability of being far less such that it may fall below the sensitivity of the Gel Card system. Now it's known and accepted that the Gel Card System has a greater level of sesitivity as compared to the tube system even with enhanced, but this is only at 15min 37C incubation. One limittation of the Gel Card System is that it offers very few enhancement options. As per the Ortho, the manufacturer of the Gel Cards that I use, the gel ingrity is lost at 30min incubation at 37C. Now the whole premise of this system is that the agglutinates are captured in the gel and prevented from migrating to the bottom of the well under centrifigul (spelling??) force. I fthe inegrity of the gel is lost then all cells and agglutinates will migrate to the bottom producing a false negative results if agglutinates were indeed present. But with the tube system one can incubate the reaction volume for an hour or longer and one can perform multiple adsorbtions as well; which begs the question, Is the gel system more sensitive than the tube system at one hour incubation? I hope we have better informed minds here then mine that may be able to answer that question. So that is the Why part, to rule out the presence of an allogenaic antibody that may have fallen under the radar of our Gel testing system. So what additional testing should be done? Extended incubation, of course, has been know to work and perhaps multiple adsorbtions as well, or at least one addition adsorbtion prior to Coombs testing; because our initial antibody screen was negative and we are trying to rule out the presence of weak yet potentially harmful allogenaic antibody. Now is all of this testing practicle in the general hospital blood bank/ Yes! What about control of this system. One possibilty is to test a series of reagent Anti D serial dilutions such that we find a dilution that does not give any reaction in the Gel Card testing system but shows reactivity after one hour incubation using the tube testing system. For multiple adsorbtions this control would yeild no reactive after the first adsorbtion but shows reactivity after the second. Once this control is establiblished keep a volume refrigerated for the rare occasion when needed, or establish the usable dilution and just prepare as needed. The further explaination of the Why comes from the gaol of perfecting the transfusable product and the rare adversities that can occur and the our governing organizations are trying to route out with practice. Case in point, look at Transfusion Reactions; one of the most striking facts present in the text published by the AABB are the extreme statistics of occurences for each topic; they all seem to be very rare occurences; and please forgive any over generaliztions here. So we are dealing with a rarely occuring phenomena (not including cancer treatment centers, I am sure that a weak backtype is much more frequent) that may cause insult to the care and prognosis of any of our patients. I thank you all in advance for any feedback here. Thank you again.