The Role of Intravascular Haemolysis and the Reticulo‐Endothelial System in the Production of a Hypercoagulable State

S ummary Infusion of autologous haemolysed erythrocytes (haemolysate) into dogs produces hypercoagulability frequently followed by actual intravascular coagulation as evidenced by depressed Factor V and Factor VIII activity, fall in fibrinogen and demonstrable pulmonary artery thrombi. Depression of the reticulo‐endothelial system by carbon or splenectomy produces accentuation of this phenomena. It is postulated that haemolysis can be an important contributing factor in the pathogenesis of ‘the syndromes of disseminated intravascular coagulation’. It is also suggested that the thrombotic phenomena associated with the generalized Shwartzman phenomenon, thrombotic thrombocytopenic purpura, the haemolytic uraemic syndrome, paroxysmal nocturnal haemoglobinuria, and incompatible blood transfusion reaction, may be related to intravascular haemolysis.