Blood contains white blood cells, platelets and plasma. Plasma plays an important role in supplying and nourishing the body. Plasma does not contain much, mainly water, so it can diffuse through the walls of small blood vessels such as capillaries.

Fresh frozen plasma is a blood product separated from whole blood within 6 hours of blood being removed from the human body and stored frozen. In blood transfusion, the World Health Organization recommends that the right type of blood, the right patient and the right time be transfused.