Obviously, running testing for ALL antigens on the panels is impractical (we don't do that for screening cells either). Also, I do not think anyone runs QC every time a panel is run.
Here in our hospital, we had done nothing for QC for panels for years, until a few years ago, when I believe there was some guidance out there from FDA or JCAHO or whatever, regarding QC practices. After all is said and done, one must at least follow manufacturers instructions for ANY test system used in the Lab.
For example, Ortho wants the panel to be "tested periodically with weak antibodies". Immucor says to "check periodically by testing antigens likely to deteriorate". We test each panel with our regular QC sera when first received, (along with a diluent negative) and then let it go at that. Neither FDA or JCAHO has had a problem with this, (although they could argue that we do not have evidence that the panel is still reactive at the END of the expiration period). Our thinking is that if it is reactive when we receive it, nothing has happened during shipment, so it should be good to the manufacturers stated expiration. This is not dissimilar to what we do when we receive new shipments of POC materials.
Scott
Hi gagpinks,
Sorry to be a bit late on this one, but I have been marking some IBMS HSD papers, whilst I am off on sick leave, and got a bit engrossed in what I have been doing.
This is not only an interesting case, but is also a very rare case.
If you read either the RCOG Green Top Guideline 65 (The Management of Women with Red Cell Antibodies in Pregnancy) or the recent BCSH Guideline (Guideline for blood grouping and red cell antibody testing in pregnancy) you will see that any antibody produced de novo after 28 weeks of gestation is not usually considered to be clinically significant in terms of causing a clinically significant haemolytic disease of the foetus and newborn. That having been said, both of the anti-D levels you quote (1.1 IUmL-1 and 4.1 IUmL-1) would be regarded as immune in nature, rather than as a result of anti-D immunoglobulin prophylaxis. Equally, however, if you read the work of the late, great Prof Patrick Mollison (quoted in the latest edition of Klein HG and Anstee DJ, Mollison's Blood Transfusion in Clinical Medicine) you will see that the production of a de novo red blood cell antibody (primary immunisation, including anti-D) almost never happens so quickly. Indeed, in most cases it takes weeks, and sometimes months (and multiple challenges to the immune system) to produce the antibody.
All that having been said, it is well known that there are three kinds of individuals that exist in terms of ability to produce (or not) red cell antibodies. There are a small number who are known as "non-responders", and these individuals seem not to be able to produce an immune alloantibody (as opposed to an isoantibody, such as anti-A and/or anti-B), however many times their immune system is challenged by an antigen that they lack. Then there are the large number of people who make antibodies after several challenges to their immune system, and after a long time (weeks or months) - the normal responders. Lastly, there are a small number of individuals (known as super-responders) who tend to make antibodies after a very small challenge to their immune system (the great Ed Synder gave a wonderful lecture at a BBTS ASM some years ago, when he described such individuals as being able to produce an antibody after a virtual transfusion - as he put it, you show them a photograph of a red cell that expresses an antigen that they do not themselves express, and BANG, there is the antibody!). BUT, although such individuals have been known about for many, many years, they do not appear in the literature as having produced a de novo antibody within a time quicker than normal.
All of the above verbiage, therefore, suggests to me that this is a secondary immune response, rather than a primary response. Now, PLEASE realise that by saying this I am in no way suggesting that you (or your colleagues) have "missed" an antibody that should have been detected earlier. What I mean by this is that the anti-D from a previous primary response may well have been there, but may well have been so weak that it would not have been detected by IAT, but only by the use of enzyme-treated red cells, and possibly by the use of an IAT using enzyme-treated red cells. In other words, by an enzyme technique, which would not have been used for your antibody screening red cell testing (this is where the very rare bit of your case comes in).
You may well say to me that this is the woman's first pregnancy and that she has never been transfused, but there are cases in the literature where a woman has been pregnant, and had a spontaneous abortion or miscarriage without her actually knowing that she was pregnant in the first place, and this could be the cause of the primary immunisation, and this may be such a case. Alternatively, she may have previously had a transfusion that she does not remember (maybe she was under GA), which involved the transfusion of a unit of blood that was Partial D. Who knows?
To go on with my lengthy answer (sorry about this, but all of my friends and colleagues say I love the sound of my own voice), experiments have been performed that show the parentral introduction of anti-D immunoglobulin into the circulation of volunteer D Negative individuals has resulted in levels of anti-D well below the threshold of 1.0 IUmL-1, which we used to use as the limit for this prophylaxis, but that, unless the woman was of particularly small stature, rarely rose above 0.5 IUmL-1. These results were after several doses of more than 1500 IU of anti-D, not just standard doses, so a level of 4.1 IUmL-1 in this woman is most unlikely to be as a result of further doses of anti-D immunoglobulin prophylaxis.
The strength of reaction is not, I can assure both of you, a way of telling whether or not an anti-D is as the result of the administration of anti-D immunoglobulin or a genuine immune anti-D! Having worked as the Reference Service Manager in an area of London that contained four hospitals that each had specialist foetal medicine units (all of which "imported" women from other hospitals, when the women had high levels of alloantibodies in pregnancy), I can assure you that a woman with an anti-D level in the thousands of IUmL-1 will often give quite weak results (vis-a-vis agglutination, as opposed to quantification or titre), because the D antigen sites of the test red cells are "swamped" by the number of IgG anti-D molecules.
I agree with you 100% A little lab lost, that the clearance of anti-D immunoglobulin is, within reason, "person specific".
Having said all of the above, I would strongly advise you gagpinks, to monitor this woman's anti-D levels every two weeks until delivery and would request (out of pure nosiness) that, after delivery, you post the results of her final pre-natal anti-D levels on here, and the outcome of the pregnancy. Would you mind?
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