Each pint may help 4 patients. Whole blood can be used by patients who are suffering massive bleeding. Blood can also be separated into components that are then used individually. Plasma is a source of proteins that stop bleeding. Patients whose own blood does not clot properly need these proteins.
Platelets also aid in blood clotting, and are needed by cancer patients.
They must be transfused within five days of donation. White blood cells help patients, including newborns, fight severe infection. Red blood cells treat anemia and increase the blood's oxygen carrying ability during surgery. Every blood donation is tested for infectious disease. Any unit that tests positive is not used for transfusion.