PURPURA

presence of large and small hemorrhages in the skin, often associated with bleeding from natural cavities and in tissues. It occurs as a result of failure of hemostasis (arrest of bleeding), which, in turn, has five major causes: (1) damage to the wall of small arterial vessels (vascular purpura), which may be due to vitamin deficiency (scurvy), bacteria, viruses, allergic reactions, or heredity (pseudohemophilia), (2) deficiency of platelets (small bodies that not only plug leakages in the vessel wall mechanically but also contain many chemicals active in the coagulation of blood) in association with such disorders as thrombocytopenia, immunothrombocytopenia, lupus erythematosus, and thrombasthenia, (3) deficiency of clotting factors, either congenital (as in hemophilia, Christmas disease, hypoprothrombinemia, afibrinogenemia) or acquired in the course of disease (especially of the liver) and the administration of anticoagulant drugs, (4) development of circulating anticoagulants of various types (abnormal proteins, antibodies) that prevent normal interaction of the various clotting factors and that are found in some blood disorders (multiple myeloma, leukemias), in diseases of the connective tissue, in radiation injury, and following drug therapy, (5) fibrinolysis, caused by the activation of a usually dormant system that is able to destroy the blood fibrin clot; this condition may occur during accidents of pregnancy, delivery, and surgery. A paradoxical type of bleeding is found when tissue materials (as the consequence of shock, trauma, burns) enter the bloodstream and cause clotting within the vessels. As the patient is depleted of clotting factors, he becomes a bleeder. This mechanism is often found behind severe hemorrhage at delivery. Treatment of purpura depends on the causative mechanism. Corticosteroid hormones are effective in controlling vascular purpura and the bleeding of thrombocytopenia. Transfusion of platelets may be a useful technique for a bleeding emergency, and surgical removal of the spleen is resorted to in certain forms of thrombocytopenic purpura when other therapy has failed. The administration of either blood or plasma or of the fractions specifically absent is the basis of the treatment of acute bleeding in disorders of blood coagulation.