An alternative approach to ABO/Rh donor unit confirmation testing

A colleague comments that the CAP Transfusion Medicine Checklist TRM.40450 states, "Are records available that document the confirmation of ABO/Rh type of all donor units as appropriate, using a sample from an attached segment?" and that the 22nd edition of the AABB Standards 5.12 states "Prior to transfusion, the ABO group of each Whole Blood and Red Blood Cell components and the Rh type of such units labeled as Rh negative shall be confirmed by a serologic test on a segment. Such confirmation may be performed either before or after labeling and need be performed only once for each unit. Confirmatory testing for weak D is not required." In the opinion of the inquiring colleague, neither accrediting agency defines the term 'confirmation' or 'confirmed' in their documents, leaving this up to the discretion of the individual laboratory. The inquiring colleague's institution has met the aforementioned requirements by testing donor units labeled A, B and AB with anti-A and anti-B; by testing units labeled group O with anti-A,B; and by the immediate-spin test all Rh-negative units with anti-D. He adds that assessors and inspectors have never taken issue that a serological test is not performed to 'confirm' the Rh type of units labeled Rh-positive. (Units labeled Rh-positive are routinely transfused to Rh-positive recipients; if an Rh negative unit is mislabeled Rh positive, the unit would be Rh compatible with the recipient.

The inquiring colleague proposes a different (iconoclastic?) approach to donor unit ABO/Rh confirmation and encourages comments: Prior to transfusion, components must have been demonstrated to lack antigen(s) to which the patient has expected antibody. If the purpose of donor ABO/Rh verification testing is to prevent transfusion of ABO incompatible red cells (and to prevent Rh sensitization of Rh negative recipients), it seems reasonable to 'confirm' that group A components lack the B antigen by testing only with anti-B and 'confirm' that units labeled group B lack the A antigen by testing only with anti-A. If a unit is labeled A and tests negative with anti-B or a unit labeled B tests negative with anti-A, is not the intent of the requirement met? If the unit is actually group O, the unit is ABO compatible with the recipient.

The following comments have been received.

1. The above question was forwarded to an internationally-recognized immunohematologist who replies that a justification for the approach outlined could be economic expediency when performing donor unit confirmation using automated gel column technology. For Red Blood Cell components if matters not if a unit labeled group A (or B or AB) is actually group O. So testing RBC components labeled A vs. anti-B cards and RBC components labeled B vs. anti-A cards should suffice, and one could argue that there is no need whatsoever to confirm the blood type of RBC components labeled AB. However, there is a requirement (AABB Standard 15.5.1) that recipients receive ABO type-specific Whole Blood; non-group O Whole Blood will therefore need to be tested with anti-A and anti-B. Further, if there are institutional policies requiring type-specific Red Blood Cells in certain clinical situations, those components need to be tested against both reagents.

ADDENDA Aug. 21, 2004

2. A colleague in Chicago poses a practical objection to the proposed confirmation approach which is outlined above. The basic objection is that the proposed confirmation protocol it is not uniform. In other words, the confirmatory testing is done differently for each putative donor blood group.  Thus, in the Chicago colleague's opinion, there would be MORE potential for manual or clerical error. He acknowledges that this possibility could be mitigated if the Laboratory Information System is appropriately configured.

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator