Every year, nearly 5 million people in the United States receive life-saving blood transfusions. During a transfusion, you receive whole blood or parts of blood such as Red blood cells - cells that carry oxygen to and from tissues and organs Platelets - cells can be used to control bleeding Plasma - liquid part of the blood that helps blood clot Some people worry about getting sick from giving or receiving blood. It is possible, but is very rare. The Food and Drug Administration and other organizations that collect blood make sure that blood is safe. Every single donation is tested for HIV/AIDS, Hepatitis C, syphilis and several other diseases that can be transmitted through blood. Some people who know they may need blood during surgery donate their own ahead of time. That is the safest type of transfusion.