Unrecognized pulmonary embolism presenting as disseminated intravascular coagulation.

Six patients are described in whom disseminated intravascular coagulation of uncertain cause was found to be due to occult pulmonary embolism. The peripheral blood smear showed thrombocytopenia in all patients and schistocytes in four. Coagulation studies revealed increased levels of fibrinogen/fibrin degradation products (six of six patients), positive results for fibrin monomer (five patients), prolonged thrombin times (four patients), hypofibrinogenemia (three patients), prolonged prothrombin times (two patients), and decreased plasma coagulation factors (two patients). Pulmonary embolism was confirmed by lung scanning or pulmonary angiography. Institution of full-dose heparin therapy was associated with hemostatic and clinical improvement in all patients. The association of disseminated intravascular coagulation with occult pulmonary embolism merits recognition since full-dose heparinization is required for successful therapy.