Terminology to use when no crossmatch compatible RBCs are available

A clinical laboratory scientist who is a transfusion supervisor in a hospital in California wonders what terminology colleagues use to convey to a clinician the situation when no crossmatch compatible RBCs are available for their patient, but laboratory testing permits the selection of one unit over another. For example, do colleagues use the terminology "least incompatible" RBCs, or some other terminology such as "best match available" depending on the degree of laboratory testing that has been done, such as autoabsorption studies to rule out underlying alloantibodies, red cell antigen phenotyping to provide phenotype matched donor RBC units, etc. He wonders if the use of the 'least incompatible' terminology could lead to confusion and a lack of confidence on the clinician's part as to the safety of a tranfused RBC product.

The following comments have been received.

ADDENDA Jan 22, 2005

1. Lawrence Petz, M.D. (attribution used with permission) emphatically agrees that the use of the 'least incompatible' terminology leads to confusion and a lack of confidence on the clinician's part as to the safety of transfused RBCs. He suspects that needed transfusions are not provided because of unreasonable fear of transfusion of RBCs that are incompatible with the patient's autoantibody. Instead of speaking rather negatively by using such terms as "least incompatible", he would suggest referring to these units as "alloantibody compatible" as long as absorption studies have been conducted to confirm this. Probably nothing serves the situation as well as a personal discussion with the clinician explaining (1) a search for alloantibodies has been performed and is negative (or, alloantibody compatible blood selected when alloantibodies are detected), (2) that all units of RBCs are incompatible with the autoantibody, as is usual, and (3) a hemolytic transfusion reaction is not to be expected, and (4) that the RBCs will survive as long as the patient's own and will provide temporary improvement in the patient's anemia.
   
   For further discussion of these points including how to interact with clinicians in this regard, see:
   • Petz LD. "Least incompatible" units for transfusion in autoimmune hemolytic anemia: should we eliminate this meaningless term? A commentary for clinicians and transfusion medicine professionals. Transfusion. 2003;43:1503-7.
   • Petz LD. A physician's guide to transfusion in autoimmune haemolytic anaemia. Brit J Haematol. 2004;124:712-716.
     
   He concludes, "When a patient with AIHA requires a transfusion, a good policy is to provide the primary care physician with a reprint of the 'Physician's Guide to Transfusion in Autoimmune Haemolytic Anaemia.' This should facilitate communication between the physician and the blood transfusion service." For a supply of reprints, send a request with mailing address to: lpetz@stemcyte.com
   
   
2. A transfusion medicine physician at an academic center in Baltimore reports that he does not like the term "least incompatible" because in his opinion it does not convey any meaningful information to clinicians. In the Baltimore physician's experience when a transfusion service looks for blood that is "least incompatible", urgently needed transfusions can be delayed while the transfusion service performs testing that looks for 'meaningless' differences in serologic reactivity due to clinically insignificant alloantibodies or autoantibodies. He adds that if alloantibodies have been ruled out by autoadsorptions, reference to the patient's phenotype, or other means to determine that the units selected for transfusion lack the antigens most likely to cause transfusion reactions, a continued search for "least incompatible" blood in the crossmatch is not useful. Although he has held these opinions for some time, a presentation at an American Society of Hematology education session by Dr. Lawrence Petz crystallized his thoughts on this subject. Dr. Petz later put his thoughts into an editorial which appeared in the November 2003 issue of Transfusion (see reference in addendum 1 above). The Baltimore physician recommends colleagues read the editorial for a more complete discussion of these issues.
   
   
3. An internationally recognized immunohematologist in Los Angeles who has published several scientific works with Dr. Petz also refers colleagues to the publication by Dr. Petz on this subject (Petz LD. A physician's guide to transfusion in autoimmune haemolytic anaemia. Br J Haematol 2004;124:712-7).
   
   
4. . A transfusion medicine physician in Chicago who has extensive experience in the field reports that the physicians at his academic center are accustomed to their use of the term "least incompatible." With regard to autoantibodies, their emergency release form contains the phrase, "Autoantibody present, least-incompatible units issued," so as to give a bit of context in that setting. He reports that they occasionally discuss compatibility testing for autoantibody patients in patient care conferences in the hematology service.
   
   
5. A transfusion medicine physician at an academic center in Michigan does not like the term "least incompatible" because in his opinion, the term is really meaningless. In communicating with clinicians, he explains the reason for the positive crossmatch: autoantibody, alloantibody of no apparent clinical significance, unable to exclude clinically significant antibody but clinical situation necessitates transfusion, alloantibody and antigen-negative blood not available and transfusion is urgent, etc. He does state that the crossmatch will be positive and the units will have labels. They use a couple of canned phases for labels: "Crossmatch positive. Antibody of no apparent clinical significance.", "Crossmatch positive. Alloantibody present. Compatible blood not available.", "Crossmatch positive. Autoantibody present."
   
   
6. A Transfusion Medicine director at an academic center in Boston has never liked the term "least incompatible" and never uses it. In his opinion, the term implies that the extent of incompatibility is somehow strongly correlated with post-transfusion success. While such a general overall correlation might be true, it is hardly appropriate for an individual patient.
   
   In his program they address this question by simply reporting the crossmatch as it is. For example, for patients with clinically non-significant allo-antibodies for which the unit is serologically not compatible but is medically appropriate for release, he reports that they would list the crossmatch result as "incompatible" (because it is). His personal view is that medical technologists should never be asked to report such units as "compatible". Depending on the specific antibody (and policy), in some cases the transfusion slips and record would be amended to include the information that release of the unit was approved by the medical director of the transfusion service. As a another example, in the case of a patient with a panagglutinin autoantibody whose plasma, eluate, and auto-adsorption demonstrate the absence of underlying alloantibodies, the crossmatch result would be listed as "compatible with auto-adsorbed plasma" (because it is).
   
   Finally, in the case of phenotype-selected units, they would simply list the relevant antigens for which the unit is negative without any qualitative statement regarding the degree of match.
   
   
7. A Transfusion Medicine director at an academic center in Northern California reports that at his hospital they use the term "least incompatible". He does not think it undermines the clinicians' confidence; in fact, he personally would be in favor of having the clinician sign a special release in order to emphasize that they cannot dispense crossmatch compatible blood, but their current policy does not require it.
   
   
8. A Transfusion Medicine director at an academic center in Connecticut is of the opinion that one should not try to convey a complex message with a simple catchy phrase, because when one tries to do so, confusion and delay will certainly result. He advises colleagues to pick up the phone, call the clinicians or even better talk to them face to face.  He advises colleagues to explain the serological science behind the issue to the clinician(s), to be visible on the ward, to be accessible to the clinician for questions and to write a note in the chart. He adds "Transfusion Medicine is not always intuitive....sometimes it is rocket science".
   
   
9. A Transfusion Medicine director at an academic center in Virginia reports that at his institution they do not use the term "least incompatible" or any other phrase. Rather, they describe the findings for the clincian and explain why the units they are providing have been selected for transfusion. The questioner has touched on a good reason not to use this terminology.
   
   
10. A Transfusion Medicine director at an academic center in New Hampshire reports that in situations like this, he usually takes the burden of compatibility responsibility on himself. He figures that the transfusion medicine physician has much more of an understanding of the serologic situation and whether the transfusion is really going to be completed safely than the clinician. He discusses the reason that the lab is unable to use routine crossmatching methods or is unable to provide the usual assurances of compatibility. If he is comfortable that the transfusion is going to be a safe event, he says that and allows the clinician to dismiss the "serologic incompatibility" from his/her mind. If he truly has doubts about the compatibility, he will learn as much as he can about the situation and then either attempt to dissuade the clinician from transfusing at this time or, if delay or an alternative is not possible, will attend the patient and help the clinician assess the outcome of the transfusion. In other words, this kind of circumstance calls for a transfusion medicine consultation in the fullest extent of the term.

ADDENDA Jan 25, 2005

11. A Transfusion Medicine Specialist in a teaching hospital in New Zealand reports that in their hospital they use the term "least incompatible". Although he does not like the term as it means little and certainly has a negative connotation, he has yet to find a suitable single term that will accurately reflect all the situations giving rise to its use. In conclusion he states: "Most clinicians do understand what we mean by this term. Sometimes it evokes personal discussion with the clinical staff, which I consider positive."

ADDENDA Jan 26, 2005

12. The Section Head of a Red Cell Immunohematology Reference Service in the United Kingdom is of the opinion that the term "least incompatible" has little true meaning in the context of this discussion. In his laboratory they simply use the term "suitable" on crossmatch labels and in ensuing printed reports to denote that, although the units are incompatible with patient's neat plasma (as all units would be), they are suitable for the patient. This is based on the fact that units are compatible with absorbed plasma and with any underlying alloantibodies found. The situation would also be discussed between Blood Center and hospital-based consultant hematologists before blood was issued.

ADDENDA Jan 29, 2005

13. A North Carolina transfusion medicine physician does not know if there is a "correct" answer for this question. His impression is that some transfusion services do choose to release such units as "least incompatible" while others (like his) have the clinicians sign a "Conditional Blood Release Form" which is distinct from their "Emergency Transfusion Request".
    
    The "Conditional Blood Release" states "I understand that the compatibility testing for the red cell containing unit(s) has been compromised because of:"z
    
    Several check boxes are provided including:

    Multiple alloantibodies
    Incomplete workup
    Warm autoantibody
    Hemolyzed sample
    other ______
    

    it then goes on to state...
    

    "It is my assessment that the benefit of transfusion outweighs the possible risk of a hemolytic transfusion reaction as noted in the patient's chart."

    and the physician signs and dates the card.
    
    One card can cover a series of units.
    
    The intent of such a card is to convey the uncertainty and perhaps incomplete nature of the compatibility testing which must be weighed against the risk of not transfusing.

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