Red blood cells (RBCs) carry oxygen throughout the body. RBCs are often needed during surgery, during trauma emergencies and to help Sickle cell patients. Platelets facilitate blood clotting. Platelet products are often needed to help leukemia and cancer patients, as well as those undergoing major surgery. Plasma contains additional clotting factors and is the liquid that carries other blood components throughout the body. It is needed for burn patients or those with clotting disorders.