What is the purpose of washing red blood cells before transfusion?

The purpose of washing red blood cells before transfusion is primarily to remove antibodies and plasma proteins. This procedure is particularly important for patients who may have had previous transfusions, who are at risk of hemolytic reactions, or who have specific immunologic conditions.

When blood is transfused, the recipient’s immune system may react to foreign antibodies present in the donor plasma. By washing the red blood cells, the residual plasma and its associated antibodies are significantly reduced, which minimizes the risk of an immune response. Additionally, washing can help eliminate some plasma proteins that may contribute to transfusion-related complications, such as allergic reactions.

Washing red blood cells does not directly increase the oxygen-carrying capacity of the red blood cells themselves, nor does it affect metabolic waste levels or prevent iron overload. The primary focus of washing is to enhance the safety of the transfusion by mitigating the risk of immunologic reactions.