A colleague in Massachusetts writes that he is puzzled by the apparently universal agreement that a patient's pre-transfusion specimen is "good" for up to three days even when the patient is undergoing daily transfusions with red cell products. His concern is that during the 3-day period over which a pretransfusion specimen is stored, a patient might experience an anamnestic antibody response that goes undetected (because a new specimen containing the emerging antibody has not yet been submitted), thus creating the risk to the patient of a hemolytic transfusion reaction. The Massachusetts colleague asks whether in a situation like this new specimens should be required that are as close to the time of additional transfusion as possible, e.g. maximum of 12-24 hours prior to infusion of the additonal red cells?

The following responses have been received.

ADDENDA June 27, 2003

1. A transfusion medicine physician at an academic medical center in Los Angeles agrees with the colleague from Massachusetts that repeatedly transfused individuals will produce newly discovered alloantibodies, and some of these antibodies will go unnoticed by the laboratory if a new blood sample is not tested more often than every three days. The e-network forum might find the article by Shulman, IA et al entitled 'When should antibody screening tests be done for recently transfused patients?' (Transfusion 1990;30:39-41) to be germane to this discussion. The Los Angeles physician reflects that like most things in medicine, setting a policy for how often a new blood sample is required for pre-transfusion testing involves a balancing act of risk and benefit, pro and con. If the Massachusetts colleague thinks that his institution can support a 12-24 hour time limit on pre-transfusion samples for recently transfused or pregnant individuals, there is no regulatory or accreditation reason why that institution should not do so. However, such a policy may not be operationally feasible, given the increased frequency that a patient will require a new blood sample for pre-transfusion testing, not to mention the need to draw these samples over a weekend and during holidays.

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