Blood transfusions and postoperative infections in patients undergoing elective surgery

Postoperative infections result from the interactions of bacteria, the surgical technique, and host defense mechanisms. Thus, identifying single determinant factors has proved difficult.

In a recent survey of 2,809 colorectal resections, transfusion was the single most powerful risk factor for postoperative infection. In patients undergoing primary hip or knee prosthesis insertion, the transfusion of allogeneic blood increased the risk of a deep-seated infection by a factor of 12.

Several host defense mechanisms are impaired by blood products. The initial hypothesis incriminated the transfused white blood cells, but this paradigm has since been challenged. The effects of free serum iron, the blood storage time, and the presence in stored blood of bioactive substances such as inhibitors of metalloproteinase-1 may also be important.

It is worth pursuing efforts to emphasize autologous blood transfusion and the reinfusion of shed blood as blood conservation strategies, as these practices reduce the risk of infectious complications.