Matched Unrelated Donor sample (MUDS)

[simret]

Hello all,

We are in disagreement among technologists at the hospital that I am working regarding "Match Unrelated Donor samples". Once the MUD sample is received, we did type and screen on the sample and were done until recently. Regardless if the donor sample is RH negative or positive. When the HPC product comes that is from this donor, we do retype on it, immediate spin cross-match with the recipient and issue it to be transfused ( we issue it even if there is ABO disagreement/ discrepancy).

  Now, my question to you all is, is it necessary to perform weak D (Du) on this sample if it is RN negative? Can you share with me what you ion your hospital.

Thank you

Simret

[David Saikin]

i think that if you are testing the donor (not the retype) you should perform the weak D. When you do the retype (after product rec'd) then you do not have to perform weak D.

[CM2]

My short answer would be No, it is not necessary UNLESS you have a conflict between your results and the donor workup documents that come with the product. 

 

Here in the US, the NMDP coordinates the majority of our searches. We get paperwork from the collection center that screens the donors which includes donor virals and the blood type they got in testing on the donor.  We also get the HLA results performed (here in NJ by the sharing network) which also includes the blood type.  So you already have 2 separate sources of a blood type which are done with a high standard of accuracy.  So if they say A neg, and I test and get an A neg on immediate spin, why would I spend energy looking for zebras? The worst that is going to happen is the patient will receive Rh neg units unnecessarily. It is also possible for a tiny subset of weak D people to make anti-D anyway, so to our minds it is taking the path of caution.  If you work in a region with very limited blood supply this might be a stronger factor to consider.   But Im guessing if you have the capability to perform bone marrow transplants, you have a fairly robust transfusion service as they can be pesky to support (HLA immunized patients needing lots of platelets comes to mind).

 

A few thoughts. Its great you do the antibody screen, I was suprised to learn the NMDP does not require these to be done on donors, and we had one case where a transplanted patient who was rh Pos suddenly acquired an anti-D, which caused a bit of confusion. We never knew if it was because the transplanted T cells from Rh neg donor decided they didnt like the recipients Rh pos remaining circulating cells, or whether the donor was already immunized from a pregnancy/rhogam greater than a year ago (thats the time frame on donor questionnaire) and already had circulating anti-D in the plasma which was also infused with product. (gel method is so darn sensitive) In any event it did not cause any harmful sequelae/DTR or anything.

 

My other thought is, you can probably save yourself the crossmatch, unless you are at one of the unlucky institutions that still has not instituted electronic crossmatch (patients with a negative antibody screen receive ABO compatible units without a physical crossmatch of serum and donor cells).  The hct on products we receive is 4-8% which usually translates to around 20-40 mls of rbcs. Much less than a unit of blood.. if electronic crossmatch is safe for 250mls, why not 20-40?   

 

We have a cap of 10mls of mismatched rbc allowed per day.  If we have a patient with antibodies or a major ABO mismatch we prefer to go the conservative route and break up infusions either into sessions 4 hours apart, or over 2 days, with hemolysis workups in between issuing the next piece to be sure some crazy hemolytic cascade hasnt started.  With this amount of rbcs and good kidney hydration, its a pretty self limiting reaction.. once those rbcs are gone, no more is coming in.  At least not until the recipient immune system finally dies out and the new one is established and starts making rbcs..and the new immune system doesnt fight itself. 

[simret]

Thank you for detailed explanation.

Simret