This is a reprint of a previous post.

During my career, the role of the transfusion medicine physician in handling RBC antibodies has evolved.  Depending on your location, either a specific transfusion medicine physician or a hematologist covering the specialty handled this.  In the United States, most hematologists nowadays do not do this.

During my US residency training in pathology, most trainees did not have an interest in blood banking and often used the rotation to take vacations.  For their board certification in clinical pathology, they crammed for the examination and afterwards did not engage in it.

When I started my career in the United States, hospitals had a hospital blood bank/transfusion service and handled most of their antibody problems themselves.  In Chicago where I practiced, many blood banks had Specialist in Blood Banks SBB graduates or SBB students working, and of course, they had a dedicated blood bank supervisor.

Currently in the United States, the hospital blood banks may be staffed by generalists and there is no one with specific antibody experience.  SBB graduates are expensive and usually work in blood centers or academic hospitals.

If you have a regional blood center with a reference laboratory, you can send your antibody workups there and let the blood center select appropriately antigen-matched units.  The physician covering the blood bank does not have to get very involved.

In the Middle East in the systems that I have run, there have been no reference laboratories and often no regional blood center.  The hospital system or the free-standing blood bank is an independent entity and must rely on itself.  The physician responsible for the blood bank must review the antibody panels and make his own decision how to select RBC components.

In the Middle East, especially in the larger centers with academic hospitals, there is usually a transfusion medicine physician who reviews the antibody workups and makes the final decision of what RBC types to dispense.  He does not have a reference laboratory to rely on.  He is responsible for the choices and has no one to refer cases on a 24/7 basis.

In the Middle East, the transfusion medicine physician must be proactive.  He must also select antigen-matched, fully or partially, and understand the trade-offs in cases with multiple antibodies.  He must know how to deal with nonspecific antibodies and antibodies to high-incidence antigens, especially if he works in a region where the antibody panels are not optimized to the local population or there are many different ethnic groups in the local area.

Thus, training someone to practice in the Middle East requires spending considerable time in technical matters that might not be necessary if he/she practiced in the West.  He may not only have to serve as a physician but he may be the equivalent of the reference laboratory supervisor.  Until such time that reference laboratories are available, this model is essential for safe practice.  Training programs for the region must reflect this and in particular, teach about specific antibodies common to the region.  He must be technically oriented and he must take ultimate responsibility for the interpretation of the antibody workups and selection of the appropriately matched units.

This is an update of a previous post.

Principle:

In 1984 effective with the 13^th Edition AABB Standards, the requirements for performing a direct antiglobulin test and autocontrol for compatibility testing were eliminated.  The DAT is very important to detect delayed hemolytic transfusion reactions, certain autoimmune conditions, and drug-related hemolysis.

Since that time, the immediate-spin crossmatch and now the electronic computer paperless crossmatch may be used for most compatibility testing in place of the classic, antiglobulin-phase (indirect antiglobulin test) crossmatch.

If an antiglobulin phase (IAT) crossmatch is performed, an RBC unit with a positive DAT will cause a false-positive reaction.  Since most crossmatching does not include the IAT, it will not be affected by the DAT status of a donor unit.

Policy:

1. Donor RBC units will NOT be routinely tested for DAT as part of component processing.
2. The type of compatibility testing selected for a particular patient should be the technically simplest one (no need to do extra work unless so instructed by the transfusion medicine consultant/designate):
3. Do a full antiglobulin-phase IAT crossmatch if ANY of the following applies:
   1. There are no two independent ABO/D typings on the patient during the current admission.
   2. The ABO/D type of the current admission does not match the historical information.
   3. The patient has a detectable antibody at 37C
   4. The patient has a history of a clinically significant antibody but no current antibody
   5. Whenever the consultant, transfusion medicine/designate requests it.
   6. Whenever the Medinfo HIIG record so indicates (in comment section)
4. Do the immediate-spin crossmatch if ALL of the following apply:
   1. Only one determination of the ABO/D type
   2. The historical ABO/D type agrees with the current type.
   3. There are no antibodies reacting at 37C AND there is no history of antibodies at 37C.
5. Use the computer/electronic crossmatch if ALL of the following apply:
   1. There are two determinations of the ABO/D type and they both agree with each other.
   2. The historical ABO/D type agrees with the current type.
   3. There are no antibodies reacting at 37C AND there is no history of antibodies at 37C.
6. When to do a DAT on a donor unit:
   1. Patient antibody screen is negative but the full AHG crossmatch is incompatible.
   2. Part of a transfusion reaction workup where the AHG crossmatch of donor cells and patient serum is incompatible.
   3. Whenever the consultant, transfusion medicine/designate requests it.
7. If a donor unit is found with a positive DAT:
   1. Required testing and review:
   2. Test with polyspecific and monospecific IgG and C3d antisera
   3. Perform an acid-elution.
   4. Send the results to the transfusion medicine consultant/designate for review.
   5. The reviewer will enter his review in HIIG in the Donor Consultation Section both as global donor comment and a result-specific comment against the antibody screen result.
   6. Use of the DAT-positive donor unit:
      1. Most of the time you will not know if the donor RBC unit is DAT-positive since we mainly use the electronic crossmatch.  It will be used if all criteria are met.
      2. Otherwise, select another RBC unit for the AHG crossmatch.
      3. The final decision to use the DAT-positive unit will be made by the Transfusion Medicine consultant/designate.

Important:  Don’t do a classic AHG/IAT phase crossmatch unless you have to do it  (see conditions above.)  A donor unit with a DAT is unlikely to be clinically significant and may be transfused safely to the patient in most situations.  Patients receiving electronic-crossmatch and immediate-spin crossmatch are receiving units with positive DAT without incident.

References:

1. Standards for Blood Banks and Transfusion Services, Current Edition, AABB, Bethesda, MD, USA
2. Guidelines to the Preparation, Use, and Quality Assurance of Blood Components, European Committee (Partial Agreement) on Blood Transfusion (CD-P-TS), Current Edition
3. Technical Manual, Current Edition, AABB, Bethesda, MD, USA, 2012

This presentation is from my time at National Guard Health Affairs Riyadh and suggests an algorithm to assess the clinical significance of the reaction. In my opinion, the essence of immunohematology testing is the antiglobulin test so I would spend much time with technical and medical staff, including trainees/fellows (even those not based in transfusion medicine) to make certain they understood how to interpret it.

If it is a neonate and the mother is ABO-incompatible, always test against reagent A1 and B cells.

This is a revised version of a previous post.