Malcolm Needs

You are far from dense! It is the fault of UK terminology! It stands for Cold Autoimmune Haemolytic Anaemia, and so, therefore, it would be far more logical for it to have the acronym CAHA, but CHAD is what it is!!!!!!!!!!!!! :)

This is certainly not done routinely in the UK, although it may be done if there is something like a known abdominal trauma (say a car smash or an assault, or something like that).

Sorry, I also meant to say that, no, the foetus can have enough blood volume to sensitize the mother much earlier than 28 weeks gestation. Indeed, if there is a sensitizing event after 12 weeks gestation in a D Negative pregnant lady in the UK, anti-D immunoglobulin prophylaxis is given (but only half of the normal dose - 250IU, rather than 500IU). :redface::redface:

This is true, but the original anti-D given was IgM (on the grounds that this would not cross the placenta) and, not only did it not work, it acted like adding fuel to the fire, because it actually promoted the production of immune anti-D. As a result, the whole anti-D prophylaxis programme was almost abandoned. The use of IgG anti-D was only tried as the result of someone (I can't remember who now, but it may have been Ruth Sanger of Race and Sanger fame) remember ing some fairly ancient work by someone else (again, I can't remember who) doing some different, but similar work. Sorry I can't be more specific, but the grey matter is getting old!!!!!!!!!!!!! :D:D:D

I would say that it is a blood product, but not a blood component, on the grounds that it is manipulated after donation (more so, I mean, than separation of fresh frozen plasma from a whole blood donation). Having said that, I'm sorry, but I don't know the answer to your question. :redface::redface:

It very much depends on how often the lady's plasma is screened for atypical alloantibodies prior to 28 weeks gestation. In the UK, the plasma is often screened at booking, and, if there are no atypical alloantibodies detected, they are not screened again until 28weeks gestation. This, in effect, is the last chance to detect clinically significant atypical alloantibodies that have developed between the booking sample and the 28 week sample. As adiescast quite correctly says, anti-D is not the only atypical alloantibody that can cause very serious hemolytic disease of the newborn/foetus; anti-K immediately springs to mind. If you miss an anti-K, becuase you abandon the 28 week gestation screen, you could end up with a very anaemic, if not dead, baby. It is extremely rare for a de novo atypical alloantibody developing in the third trimester to cause clinically significant haemolytic disease, and so we do not tend to screen after the 28 week sample. So, as I say, it depends on the number of screens and the timing of the screens, but I certainly would not advocate abandoning the 28 week screen (and, in any case, in the UK, this screen is written into the BCSH Guidelines on testing during pregnancy). :salute:

Actually, in certain circumstances (CHAD) there is evidence that the opposite is true! This is shown under, References, Document Library, Educational Material, "Laboratory investigation of Autoimmune Haemolytic Anaemia" (which is listed on the second page), Slides 80 and 81. :):)

I hope that the ED doc was thoroughly ashamed; but I have my doubts! :(

Well, nobody is perfect. The difference is that most people that work in blood transfusion are prepared to admit it (unlike some other health professionals - and I use the term "professionals" in its loosest sense here). :(:(

Also excellent points.

All very good points.

Yes, we do that too (in fact the new/revised bits are highlighted on all copies, including the master), but we have a Task-based Training Record Sheet that has to be signed off by the trainer, as well as the trainee (part of the Good Manufacturing Practice insisted upon by the EU Blood Directive). However, once these are all signed off (1 month maximum) the paper copies have to be destroyed and only electronic copies are available. This, apparently, is so old copies cannot be used. The trouble is, of course, that people keep their own photocopies or scraps pf paper as an aide memoire. The other two problems come when we haven't performed a procedure for ages, and the computer is down, or you can't remember the exact title or document number. You put in a key word, and about a 1000 documents come up. :mad::mad::mad::mad::mad:

Yes, you are quite right in what you say. :D:D:D

Well, it is rare (extremely rare), but it could be that the child was a D Neg chimera (as a result on conjoined twins) who had fully absorbed the twin (who was D Pos) and that the maternal anti-D wiped out the D Pos clone. This is nothing more than an unlikely, but possible, explanation. The DNA profile from his leukocytes would be interesting, one way or the other. :confused::confused:

Not if you use monoclonal IgM anti-D reagents.

Yes, when we issue blood as "suitable for", we always warn that the blood should be transfused slowly and that observation of the patient during the transfusion is of paramount importance (not that it isn't anyway, but you know what I mean). :):)

Sorry to be a pain, but could you explain this a bit more please? Do you mean post-Rhogam, or just drop the screen full-stop? :confused:

Is the blood used for an IUT not irradiated to prevent this (and TA-GvHD) happening??????????? :eek::eek:

Yes, I agree with you Kate that everyone reports to someone else, and from a Managerial point if view, I think that this is right. What worries me, and I think a lot of others working in Blood Transfusion Laboratories in many hospitals in the UK, including some very big teaching hospitals, is that the person running the Blood Bank is not only managerially subordinate to the person running Haematology, but is also often subordinate to them on a technical level. As I said in an earlier post, herein lies the problem, because some of these people, with very little knowledge of blood transfusion (and that often learned many, many years previously) do tend to interfere and throw their weight around in the Blood Transfusion Laboratory itself, when the person in charge of this Laboratory knows a great deal more about the subject, and is usually very much more up to date with their knowledge. :(:(

Well, actually, we do too at the Reference Laboratory. It's on the grounds that we never believe anyone else's results but our own, and if the patient has been recently transfused and we get a mixed-field reaction with anti-D, we will report it as "D??". :redface::redface:

I agree, but in this case it did not take a lot of thinking to know that the procedure invented by the Medical Director made no sense whatsoever!!!!!!!!!!!!!!!! :eek::eek:

If we are cross-matching for a patient with a low-frequency antigen or a patient with WAIHA or CHAD, where we actually find the cross-match compatible, we will call the cross-match "compatible". If we are cross-matching for a patient with WAIHA or CHAD, where the cross-match itself is either incompatible, or we are cross-matching with adsorbed plasma, or we are cross-matching for a patient with an antibody against a high-frequency antigen, such as anti-Kna, where we know that there are no clinically-significant atypical alloantibodies present, we will use the term "blood suitable for...Joe Doe...". There was an excellent editorial by Lawrie Petz a few years ago on this subject, which is still very valid and worth a read. Petz L. "Least incompatible" units for transfusion in autoimmune hemolytic anemia: should we eliminate this meaningless term? A commentary for clinicians and transfusion medicine professionals. Transfusion 2003; 24: 1503-1507. :):)

1. At least one, if not more (it's national). 2. Once a day (in the early hours, between about 01.00hrs and 02.00hrs - which is a real pain in the b*m if you are trying to issue a cross-match, because at thet time of the morning, it's got to be urgent, otherwise we wouldn't be doing it, usually involves a bleeding liver transplant with 5 antibodies minimum, and, because we then have to issue by hand-written compatibility labels, usually involves a Sri Lankan name - but hey, it's got to be done some time, and that is the time when the computer is least used)!!!!!!!!!!!!!! 3. I'm not sure, but I think none (I think, which is always dangerous, that the server writes to a tape/CD-ROM, or whatever the IT bods use, all the time). :):)

Excellent points Carol. :):)

Only if the case is on computer already. If the patient is new, or was wrongly grouped before, or the present or previous sample was taken from the wrong patient, or the unit were incorrectly grouped, then NO!