Bone marrow transplant blood requirements

This is most likely to be a transfusion paper question, and often comes up as an exam favourite because it's an easy question and lots of people struggle with it. It's not quite straightforward to work out blood switching groups in the viva setting, so you have some time to figure out which blood groups you should need. Depending on your learning style, it may be easier to memorise the whole table or otherwise to work it out from first principles.

Don't forget that all patients will require irradiated blood if the question is general about what blood requirements are needed (and CMV negative - depending on the recipient serology and local hospital protocol (most hospitals now do not issue CMV serotyped blood in view of SaBTO guidance)).

Just to recap:

• Minor mismatch - Donor can give red cells to recipient without a transfusion reaction (eg. an O donor and a A recipient)
• Major mismatch - Donor cannot give red cells to recipient without a transfusion reaction (eg. a B donor and a O recipient)
• Bidirectional mismatch - eg. donor is B group and recipient is A - or vice versa.

The key time points for blood group switching are:

• time at start of conditioning
• time when DAT becomes negative on group and save in the recipient (this means that the relevant ABO antibodies from the serum have disappeared from circulation)
  • often transfusion labs will want the DAT to be negative on two separate occasions before switching the blood groups to the donor group.
• time when red cells from the recipient are no longer being produced (should be 120 days from engraftment - the lifespan of any red cells remaining from the ABO type of the recipient).

Please remember that electronic issue cannot be done for these patients and crossmatch must be done manually.

If you prefer to memorise the tables this is attached below as an spreadsheet.