They are given when a person's life is threatened by loss of blood. Blood transfusions are often needed for accident victims, surgery patients, and people with blood disorders. Whole blood or blood components can be transfused. Transfused blood may come from volunteer donors or from the patient.
Blood is transfused through a vein.
The amount of blood required depends on the amount lost or on the severity of the blood disorder. The patient's pulse, blood pressure, and temperature are measured regularly during the procedure. In whole blood transfusions, blood types must be compatible with that of the person receiving the blood. If not, red blood cells will rupture and clump, a condition that can result in kidney damage, jaundice and death. This reaction is called a transfusion reaction.