What is the term for a transfusion of blood that is voluntarily donated by another person?

The term for a transfusion of blood that is voluntarily donated by another person is homologous transfusion. This type of transfusion involves using blood from a compatible donor, which is collected and stored for use in patients who require blood transfusions due to various medical conditions or surgical procedures. The term "homologous" refers to the fact that the donor and recipient are not the same individual, emphasizing that the blood comes from an external source.

In contrast, autologous transfusion refers to blood that is collected from a patient in advance of a procedure and then reinfused back to that same patient. This method reduces the risk of transfusion reactions and infection since the blood is the patient's own. Crossmatch transfusion is a process that ensures compatibility between the donor's and recipient's blood before transfusion but is not a type of transfusion by itself. Emergency transfusion typically involves the rapid administration of blood products in a situation where there is significant blood loss and time constraints, but it doesn't specify the source of the blood. Each of these terms relates to specific contexts of blood transfusion, but homologous transfusion clearly defines the scenario of using blood donated by another individual.