How long does RHIG really persist?  The package insert says one thing, but with Rh-loving methods such as solid phase, I feel like I see RHIG hang around a lot longer. I think this has implication for pregnant mothers who have suffered from trauma or miscarriage prior to their current pregnancy.  Thoughts?

We have seen it up to 12 weeks post injection.  A bet a lot depends on the mass of the woman.

18 minutes ago, David Saikin said:

We have seen it up to 12 weeks post injection.  A bet a lot depends on the mass of the woman.

Very polite way of putting it... It would be interesting to compare the ones IV due to their mass compared to the ones just under the cutoff and still having it IM.

1 hour ago, David Saikin said:

We have seen it up to 12 weeks post injection.  A bet a lot depends on the mass of the woman.

 

1 hour ago, Auntie-D said:

Very polite way of putting it... It would be interesting to compare the ones IV due to their mass compared to the ones just under the cutoff and still having it IM.

Actually, this has been done.  It was a poster presented at BBTS ASM some years ago now at, I think, but don't quote me on this, Bournemouth.  I can't remember who were the authors, although one of them was certainly Dr Fiona Regan, and it won a prize (sorry to be so woolly about the details, but I am working from home today, and so don't have access to all my books, reprints, etc).  Anyway, the bottom line was that the equation used for the Kleihauer test result relies on the woman being a Standard British Issue in terms of weight, height, etc, and, of course, all women average out under a bell-shaped curve (meaning some will fall outside the Standard British Issue woman, but still be within the "normal range", and some humans (including me) will fall well outside the average (in my case, not because I am exceptionally tall or short, or because I am under weight - which leaves one alternative!!!!!!!!!!!!!!!).

Just one problem there Malcolm.  You've forgotten the most important reason.  You aren't a woman!!

You noticed Anna - I thought I had hidden that fact well!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I've heard that it can be detected occasionally up to 6 months later.

We have seen it once in a while out in the 5-6 month range with  Ortho Gel.

Gerald

Yes, it very much depends upon the sensitivity of the test being used, and on the catabolic rate of the breakdown of the immunoglobulins in the person to whom the anti-D was given.  Remember that the figures given in, for example, Mollison, for the half-life of immunoglobulins is only an average, with the normal bell-shaped graph applying, and sometimes the "normal" for a particular individual will be well outside the two standard deviation mark.

I've always wondered about the women who have gotten RHIG at 28 weeks and it not show up at all in Gel at delivery.  

Hello,

I suggest you this article! They compare different techniques ... 

"Interpretation of pretransfusion testing in obstetrical patients who have received antepartum Rh immunoglobulin prophylaxis"

A. J. Szkotak,1 B. Lunty,2 S. Nahirniak1 & G. Clarke1 

International Society of Blood Transfusion Vox Sanguinis (2015) 

Szkotak_et_al-2015-Vox_Sanguinis.pdf

On 6/27/2016 at 7:58 AM, amym1586 said:

I've always wondered about the women who have gotten RHIG at 28 weeks and it not show up at all in Gel at delivery.  

Is it possible that all the RhIg was neutralized by RH positive red cells? 

4 hours ago, diplomatic_scarf said:

Is it possible that all the RhIg was neutralized by RH positive red cells? 

It could also be that insufficient RhIg was given in the first place.  How should I put this, umm, not all women are of the same size, and this makes a difference.

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Edited May 18, 20205 yr by diplomatic_scarf
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"Does anybody know what time it is" Chicago, 1970.

Does anybody know what titer it is?

Simple question, answer not too simple.   If you are following titers of a specific antibody for a specific reason (anti-D, pregnancy),  it is important to establish the method you use is reproducible and that it correlates with what the physicians that are going to be using that information for.   As has been pointed out with previous responses,  the methods used for antibody enhancement may affect the endpoint results of the antibody titration.   The physician is often attempting to make a decision for the care of the mother and her child, current or future.   The laboratory should provide a interpretation of the results based on results they have laboratory data and based on histories of patients previously followed.  Certainly, literature should be searched for information that has been shared regarding this subject, as the one previously mentioned, however, if your laboratory is involved in following titrations and clinical significance, it is probably important you established the data for your own laboratory.