neonatal quandary

[labgirl153]

Look over this scenario:

A 32 yr. old woman suddenly presents who is A Rh pos with anti-E, anti-c (stimulated by a pregnancy in 2003). She is now set to deliver twins at 34 weeks gestation. No titers have been done and her husband's ABO and phenotype are unknown, although it's safe to assume he possesses E and c since their first baby exposed the woman to these antigens. As a precaution, prior to the delivery, the transfusion service finds a fresh, irradiated, CMV neg, O Rh Pos, E neg, c neg quad unit that is compatible with the mother. Even though the ABO and phenotypes of the infants are unknown, the neonatal O neg unit won't be available for these babies since (as you know), most Rh neg donors are either homozygous or at the least, heterozygous for c.

The infants are delivered, cord bloods and peripheral blood show that twin “A†is A Rh Pos with a negative DAT. Twin “B†is O Rh neg with a positive DAT. An elution from twin “B†demonstrates anti-c, but anti-E can't be ruled out. This baby is anemic and the M.D. wants to transfuse within an hour...it's even possible that an exchange will be necessary but right now the physician wants 60 cc transfused stat. The supplier doesn't have any O Rh neg of the r' r' haplotype readily available and certainly not on a stat basis.

Quick...what do you transfuse and why?

In this scenario, the mother must be R1r' (CDe/Cde) and the father is likely: R1r'' (CDe/cdE). There is a 25% chance of getting an r'r'' child (Cde/cdE) and a 25% chance of getting an R1R1 child (CDe/CDe). The other combinations could be R1r' and R1r'' (like either parent).

I put this theoretical question to my co-workers and got some interesting responses, but the cardinal rule is to transfuse what is compatible with the mother and what is ABO compatible with the infant. Also...believe the baby's immune system isn't mature enough to recognize or respond to the D antigen present on an Rh pos donor so...let me know what you folks think.

[donellda]

Interesting scenario! In our facility, a problem like this would definately be left for the blood bank medical director to decide. My first thought while I was reading this was to go to an O positive R1r' donor. Since a newborn does not have the ability to produce antibodies, the Rh D antigen should not present a problem at this time and we need to honor the anti-E and anti-c in the mother's serum. I also wondered if Rhogam could be given but in the case of a neonate, the passive D would coat the Rh D postive cells which are then removed so I guess this wouldn't help the babies anemia. Anyway, it does present with a bit of predicament. Glad I can leave this one for a pathogist.

[labgirl153]

I agree with you Donellda...it's best to go with the Rh pos unit and "worry" about the exposure to the D antigen later. I'd hoped this would have been the normal response to my theoretical scenario but among a couple of folks I quizzed this was went too far against what they've had preached to them in the past.

In my mind, it comes down to immunology vs. "protocol" and I would hope that folks would think through this i.e. what's happening in vivo and have some understanding of immunology before turning away what is best for the infant. We tend to think of immune response in terms of what happens in an intact mature system, but in a newborn, particularly a premie, all the steps from recognition to response are huge unbridged steps from T helper to cytokines to B memory cells etc. so exposure to foreign antigens doesn't have the same consequences as it does for an older child.

BTW, this same scenario was close to occurring at my facility. We did have a woman set to deliver with anti-E, anti-c who was A Rh pos. And I did place a stat order for a neonatal O Rh pos, E=, c= unit just ahead of the deliveries. Fortunately, the twins who were both of her type and phenotype, neither of whom required blood throughout their stay.

The reason for posing this question to my co-workers soon after the real event (and to y'all), was a concern over what if anything a tech would do in a situation where the baby was Rh neg having the "offending antigen" attacked by maternal antibody, i.e.

1) Would they have immediately recognized that transfusing the O Rh neg unit was unsuitable?

2) And recognizing this, would they have understood the immunology behind this enough to have consulted with the pathologist on-call to get a final decision (this scenario occurred late in the evening with a lone tech on a weekend).

3) Finally, would the pathologist (unlikely to be a transfusion specialist) have been given enough time and info in a quick call out of the blue to really consider the right decision?

I'm just grateful that we can discuss these situations before they happen so everyone has a chance to think about it and hopefully do the right thing in the future regardless of protocol or what they were taught years before. :cool:

[donellda]

I think a lot of people still look at giving Rh positive blood to an Rh negative individual as a complete no no especially in the case of an infant. I was lucky enough to work for a health system with an excellent medical director who had a fellowship in transfusion medicine. We had our blood bank leadership meeting every week and we presented case studies such as the one you just presented.

I remember discussing a case involving massive transfusion of an individual with a clinically significant antibody. Her response was that if the individual is massively transfused it is very unlikely that the individual would have an immune response to antigen positive blood. It is good to try to provide antigen negative but in a life threatening situation it is probably better to give the antigen positive blood and basically worry about it later especially if the patient has already replaced his own blood volume. It sounds scary but I think her point is a good one.

Thanks for posting this scenario. I think it would be nice to have others just to get everyone thinking.

[BSIPHERD]

Is twin "B" a girl or boy?

[labgirl153]

hermaphrodite.

[BSIPHERD]

With a boy or a hermaphrodite I'd go with the Rh Pos. Any baby the Rh Neg hermaphrodite would have would be Rh Neg. And for life threatening anemia, the sex wouldn't make a difference. You can't have any babies in the future if you die now.

[Gloria]

I also worked with a very good blood bank pathologist who was not afraid to do things out of the ordinary and when it came to it, he always said: "halitosis is better than no breath"

[labgirl153]

Follow-up on this topic posted long ago!

An additional strategy to think on:

Since double-exchanges are frequent when an exchange for infants occurs at all, I would advocate exchanging the O Pos R1R1 reconstituted unit first, (compatible with mother, group compatible with baby), then draw a sample from baby, test to see if any maternal antibody remains in baby's system. If none remains, then on the second exchange, transfuse the O neg reconstituted unit. This would solve the problem of possibly stimulating the baby's immune system to form anti-D, plus there would be no danger of a transfusion reaction since the maternal anti-E, c would have been flushed out of the baby's system.

Apparently, there is a possibity, however slim, that the newborn will develop anti-D...

Have found ONE paper in which one premature infant was immunized to D following a platelet transfusion:

Transfusion

Volume 44 Page 747 - May 2004

Issue 5

However...this is the only case I know of having been documented. As you all know, it's uncommon for adults to form anti-D after platelet transfusion; therefore the risk of infants, particularly for premature ones must be quite a bit lower. The group who documented this suggested administering prophylaxis (Rhogam e.g.) but I have not seen anything concerning dosage or safety in infants with this drug (as yet).

If anyone has read of more allo-antibodies formed by newborns as a result of transfusion, please post!

[Yanxia]

I think we also can exchang with the same phenotype as the infant's blood.

Because through the process part of the antibody and the cells which is coated will antibody will be drawn out, so the hemolysis will lighten even infuse the blood express the antigen. And I agree with the method you have mentioned. If the antibody titer is high I will do as you do ,if the antibody titer is not hight ,I will do like this.

[Lcsmrz]

These are the situations that get dumped on the pathologist, who has to talk to the clinician, weigh the risks of each available option, and deliver a response. Sometimes it's a time-sensitive issue, rather than a component-of-choice one.

I don't always agree with what they tell me to do, but I don't have their medical background or the clinical information. And I can sleep at night, knowing I didn't make the decision ...