What should be done with an incompatible donor red blood cell unit that has a positive DAT?

When dealing with an incompatible donor red blood cell unit that displays a positive direct antiglobulin test (DAT), the recommended course of action is to discard the unit. A positive DAT indicates that antibodies or complement components are bound to the patient’s red blood cells or the red blood cells in question. Incompatibility suggests that the recipient's immune system has reacted against the donor red blood cells, which can lead to a hemolytic reaction if the unit were to be transfused.

Discarding the unit is essential for patient safety, as using an incompatible unit can result in severe adverse reactions. It is critical to understand that a positive DAT in this context signifies the presence of a potentially dangerous situation for the patient.

Antigen typing, washing the cells, or performing a panel may provide additional information about the nature of the incompatibility, but these actions do not mitigate the risk to the patient posed by transfusing a unit that is already known to be incompatible. Thus, discarding the unit is the safest and most appropriate immediate response.