Rh type of DAT positive baby

[Rhona24]

We have a mother with an Anti-D of 212 iu/ml . An IUT was performed 3 weeks before delivery.The baby's sample was tested and found to weakly DAT positive with an IgG coating. An Rh type was carried out on the baby- the baby typed as a straightforward ccde by Diamed gel. An eluate was performed on the baby's cells however after 20 washes the last supernatant still showed the presence of Anti-D.

The Rh type of the father is unknown.

It is possible that the baby is D positive and all the antigen sites are blocked however

assuming, that the father is RhD positive, why is the presence of a C or E antigen not detected? ( It seems unlikely that the father is Ror)

Also why is the DAT only weakly reactive?

[Malcolm Needs ☆]

The chances are that the baby is D+, and it could be that the D antigen sites are blocked, but, with an anti-D level of 212 IU/mL (remember, anything over 15 IU/mL could result in hydrops), the chances are that most of the baby's red cells have been destroyed in utero, and that what you are testing is the blood given during the IUT (which would be group O, rr, K- and all the other things like <5-days-old, PANTS negative, CMV negative, K-, etc).

This would explain why the DAT is only weakly reactive (very, very few D+ red cells around), and also why the C and/or E antigens are not reactive. You could try adsorption and elution with a pure anti-C (be careful, most reagent anti-C's are really anti-Ce, even the monoclonals) and a pure anti-E, reacting the elution against an r'r and an r"r.

The fact that the baby was given an IUT will also supress its own erythropoisis (I can never spell that!).

With a maternal anti-D level of 212 IU/mL (and remember, the concentration of the anti-D in the baby's circulation could probably be higher than that, as the IgG immunoglobulins are actively transported across the placenta), I'm not surprised that you cannot get an unreative last wash.

REMEMBER, AS THE BABY WILL PROBABLY REQUIRE FURTHER TRANSFUSIONS, ALL CELLULAR COMPONENTS SHOULD BE IRRADIATED.

[Rhona24]

We did think that it was possible that we were typing the transfused cells so we contacted the hospital to ask what the baby's Hb and bilirubin levels were. The baby had a Hb at delivery of 16 and a bilirubin of 96. A few days later the Hb had dropped to 11.7 and the bilirubin risen to 188. The baby was given a top up transfusion 20 days after delivery.

I am struggling to think of a logical explanantion for these test results as it looks as if the baby's own cells were not all destroyed by the maternal Anti-D

We have asked for a repeat dample at a future date to repeat out tests.

[Malcolm Needs ☆]

We did think that it was possible that we were typing the transfused cells so we contacted the hospital to ask what the baby's Hb and bilirubin levels were. The baby had a Hb at delivery of 16 and a bilirubin of 96. A few days later the Hb had dropped to 11.7 and the bilirubin risen to 188. The baby was given a top up transfusion 20 days after delivery.

I am struggling to think of a logical explanantion for these test results as it looks as if the baby's own cells were not all destroyed by the maternal Anti-D

We have asked for a repeat dample at a future date to repeat out tests.

The thing to remember Rhona24, is that, these days the Neonatologist/Foetologist at a Specialist Foetal Medicine Unit would not give an IUT on the grounds of the anti-D level (in this case 212 IU/mL), but would do so following the results of such parameters as MCA Doppler/ultrasound to ensure that the baby/foetus is anaemic enough to warrent such an invasive procedure.

This suggests (quite strongly to me) that the birth Hb of 16g/dL was mostly due to a mixture of the baby's own D+ red cells and the transfused D- red cells. The baby's own D+ red cells would continue to be destroyed by the maternal anti-D after birth, hence the fairly abrupt fall in Hb and the concommitent rise in bilirubin.

I am not at all surprised that the baby required a top-up transfusion following birth (I am more surprised that the baby did not require an exchange transfusion, unless the IUT was substantial, or that the anti-D level rose dramatically just prior to birth). I would not be surprised to learn that the baby required further transfusions, as the very fact that s/he has received an IUT and an exchange will dampen down her/his ability to produce her/his own red cells for a while.

Would you mind telling us, please, was the mother's anti-D level high throughout the pregnancy, was the baby induced prematurely and, why did nobody think to send a sample of the mother's peripheral blood to the IBGRL (I presume here that you are in the UK, from the fact that you quote IU/mL, rather than a titre) for foetal genotyping during the pregnancy?

:faq::faq:

[Rhona24]

The Anti-D level rose steeply in the last trimester of her pregnancy. I know from experience that these babies are not usually as severely affected by HDN so I wasn't surprised that he did not need an exchange transfusion.

I agree that the delivery sample was probably a mixture of of the baby's own cells and the transfused cells and that the D antigen is blocked by the maternal antibody but what I don't understand is why they are typing as ccde with no mixed field reactions with the A/C or A/E. I am assuming that if the father is D+ he is likely to be either C+,E+ or both.

The mother went into premature labour, but I think from memory she was about 36 weeks.

A sample would only be sent for foetal genotyping on request by the referring hospital.

[Rhona24]

The Anti-D level rose steeply in the last trimester of her pregnancy. I know from experience that these babies are not usually as severely affected by HDN so I wasn't surprised that he did not need an exchange transfusion.

I agree that the delivery sample was probably a mixture of of the baby's own cells and the transfused cells and that the D antigen is blocked by the maternal antibody but what I don't understand is why they are typing as ccde with no mixed field reactions with the A/C or A/E. I am assuming that if the father is D+ he is likely to be either C+,E+ or both.

The mother went into premature labour, but I think from memory she was about 36 weeks.

A sample would only be sent for foetal genotyping on request by the referring hospital.

[webersl]

blood given during the IUT (which would be group O, rr, K- and all the other things like <5-days-old, PANTS negative, CMV negative, K-, etc).

I'm in the USA; not familiar with PANTS. What does that stand for, please?

[Rhona24]

I am not familiar with the terminology PANTS either. I am guessing it must be something to do with Anti-A and Anti-B titres or donor accreditation.

[Malcolm Needs ☆]

Sorry, I wondered when I put that in whether I should have explained.

The plasma from the donor units is tested for atypical antibodies using enzyme-treated red cells, with the plasma at a dilution of (I think) 1 in 50.

However, if the blood is to be given to a baby, we do a proper screen on neat plasma, using untreated red cells.

This screen is called a PANTS screen = paediactric antibody screen.

I have no idea who thought that one up - but it wasn't me!

:haha::haha:

[Malcolm Needs ☆]

I am assuming that if the father is D+ he is likely to be either C+,E+ or both.

I, too, am making the assumption that the lady is of White ethnicity, from what you post, but it must be remembered that, although Ro is far more common amongst the Black population than the White, it is not unknown for White individuals to be Ro (about 2%), so it is possible that the baby has inherited the Dce haplotype from the father.

:devilish::devilish:

[janet]

So have titres fallen further by the way-side? Sounds like some labs are able to actually quantitate antibodies ..... how is this done anyway???

[Malcolm Needs ☆]

So have titres fallen further by the way-side? Sounds like some labs are able to actually quantitate antibodies ..... how is this done anyway???

We do this for anti-D and anti-c, but not for any other antibodies. We use a continous flow analyser. If you can give me an email address, I can send you a few photographs in a lecture I put together, but it is too big to attach here.

Actually, come to think of it, there is a lecture on here that shows it. If you go into Library, go to Educational Material and scroll down to the lecture on HDFN, they are in there.

Edited May 28, 2011 by Malcolm Needs
Forgetfulness!

[Yanxia]

We have a mother with an Anti-D of 212 iu/ml . An IUT was performed 3 weeks before delivery.The baby's sample was tested and found to weakly DAT positive with an IgG coating. An Rh type was carried out on the baby- the baby typed as a straightforward ccde by Diamed gel. An eluate was performed on the baby's cells however after 20 washes the last supernatant still showed the presence of Anti-D.

The Rh type of the father is unknown.

It is possible that the baby is D positive and all the antigen sites are blocked however

assuming, that the father is RhD positive, why is the presence of a C or E antigen not detected? ( It seems unlikely that the father is Ror)

Also why is the DAT only weakly reactive?

If it is because the antibodies block, eluate the cells will get the right antigen typing, be cautious add an D positive cells paralel as control in case the antigen is destroyed by the eluation method to get a false neg result.

And another guess, maybe the antibody not anti-D , or the baby is Del.

[galvania]

Dear Rhona

You would only see a mixed field picture of there were enough (>5%) of the minority population of cells (ie the baby's own cells) when using normal gel techniques. In this case, it rather sounds as there were really not that many of the baby's own cells left left. The DAT would be more sensitive at picking up the baby's own cells than looking for mixed fields

[heathervaught]

Genotyping the baby using a buccal swab would probably provide the information that you are looking for. I would ask your Reference Lab if they have the capability to do that, and if not, I know of a few that can.

[Malcolm Needs ☆]

The IBGRL in Filton would certainly do it.

[adiescast]

We had a case like this in which the mother had high titer anti-D and Anti-C. The fetus had multiple IUT infusions before birth and did not require exchange after birth. The funny thing with this child is that he never recovered his D type (or hadn't at 2 years out, which is the last we saw of him). I don't remember his C/E type off hand.