Donated blood plasma. Haematologist holding a bag of type O Positive blood plasma in the haematology lab of a hospital. Blood plasma is the fluid in which the blood cells are suspended. It consists of a solution of inorganic salts with a high concentration of proteins, along with fats, glucose, hormones and clotting factors. Plasma transfusions are used to treat patients with deficiencies in plasma components or those with abnormally high concentrations of plasma-bound agents.