Patients undergoing ABO incompatible stem cell transplants have very specific transfusion requirements. Do you know what group to give and when? Let’s discuss the issues…

#blooducation

ABOi SCT now comprise 25-50% of alloSCT. Why? Because it increases the number of potential donors available to a given patient.

For transfusion considerations, there are 3 phases
1.Pre transplant --> give recipient group
2.Transplant phase --> read on…
http://3.Post  transplant --> give donor group

Phase 2 starts with conditioning chemo. Phase 3 starts when the group has fully switched. Our criteria are
1.DAT neg
2.Forward AND reverse group donor type with no discrepancies/mixed fields. This wil be when transfusion no longer reqd as transfusions will “mess up” the group.

So which group to give during phase 2? Essentially you just need to make sure you are not giving anything that is incompatible with EITHER the donor OR the recipient. This will usually mean giving universal group components (but not always…). Let’s talk it through.

For red cells, we don’t want to give red cells that may be destroyed by recipient, or incoming donor, antibodies. This is nearly always going to be group O… except when .... ? (have a guess if you don't know!)

If the donor or recip is AB, and the recip or donor is A or B, then instead of giving group O, you can give the type that both parties have in common, e.g. donor AB, recip A, give A. Donor B, recip AB, give B. You’re still giving blood that will be compatible to both types.

For platelets its a bit more tricky. We are concerned with transfusing _antibodies_ that may destroy red cells. Again, we will usually give universal group. However, universal platelets are A (not AB). So where the groups are O and B (or AB and B), we will give B instead.

For AB donor or recip in theory we should give AB platelets but since we can’t, we have to make do with the “best fit”. Just like red cells, we’re going to give the group in common e.g. A recip, AB donor, give A. AB recip, B donor, give B.....

In theory there is a risk of haemolysis e.g. AB donor, A recip, transfusing A platelets gives a risk of anti B causing haemolysis of donor cells. But remember we will be transfusing group A red cells during this time.

Plasma is like plt – antibodies not antigens transfused – BUT AB plasma is available so if either donor or recip is AB, that is what we'll give; there are A and B antigens present, whether donor or recip derived, so the best choice plasma contains neither anti-A nor anti-B.

<Break/light relief. This topic is a bit heavy...>

Briefly, for D, things are (thankfully!) easier. There is debate but I’ll give current @NHSBT guidance.

If either donor or recip is D neg, give D neg from phase 2.

Then if donor is D pos, you can start to give D pos cells (RBC or plt) as soon as D pos cells are detectable.

Ready for a test? What group would you give during the initial transplant period/phase 2 for the following scenarios?

Recipient A+, donor O+. Red cells will be

Yes, the red cells will need to be O+. This is a minor incompatibility. Anti A (donor) and anti-B (donor and recip) need to be accounted for.

Next Q:
Recipient O-, donor B+. Platelets will be

Platelets will be B-. B platelets only have anti-A which will not be a problem here. D neg RBC/plt should be given until D+ cells detectable.

Next Q:
Recipient AB+, donor A+. Red cells will be

Red cells will be A+. You could give O, but why would you? The only antibody here is anti-B from the donor and so A cells can safely be given.

Next Q:
Recipient B-, donor AB+. Plasma will be

AB plasma should be given here as there are A and B antigens at play. D doesn’t matter as plasma is acellular

Final Q:
Recipient A+, donor B-, platelets will be

A- plt should be given as we would go with recipient type. We’re going to be giving O red cells (as anti-B from the recip and anti-A from the donor), so until there is engraftment of red cells, red cells will be A or O. Therefore group A platelets are the most appropriate.

I hope that was a useful run through practicalities of transfusion in ABOi SCT. You’ll note I didn’t mention major/minor/bidirectional incompatibility. These terms are useful in thinking about complications but for blood groups I prefer to think from first principles.

NHSBT guidelines are here https://nhsbtdbe.blob.core.windows.net/umbraco-assets-corp/14864/d4b11163-d079-4cf7-be1d-50baa5788066.pdf

and I recorded a @blooducation podcast on this topic with @DrJEGriffin last year and you can listen to it here https://blooducation.co.uk/portfolio/blood-support-for-abo-incompatible-stem-cell-transplants-dr-james-griffin