What is disseminated intravascular coagulation (DIC)?

Causes and Symptoms

Disseminated intravascular coagulation (DIC) is a disorder that occurs as a life-threatening complication of many different conditions. It is most commonly seen as a complication of bacterial, fungal, parasitic, or viral infections; inflammatory bowel disease; pregnancy; cancer; surgery; major trauma; burns; heatstroke; shock; transplant rejection; toxicity resulting from recreational drug use; or snakebite. It can occur as either an acute or a chronic condition, depending on the underlying cause.

In both forms, DIC involves the systemic activation of the hemostasis system. In its acute form, DIC involves hemorrhaging, the development of ecchymoses, bleeding of the mucosa, and depletion or absence of platelets and clotting factors in the blood. In the most severe cases, it is accompanied by extensive consumption of the proteins involved in coagulation, significant deposits of fibrin in the vasculature and organs, and bleeding that may lead to organ failure and death. In its chronic form, it is more subtle and usually includes thromboembolism along with activation of the coagulation system.

In acute DIC, the introduction of tissue factors into the circulation (from injury, surgery, or tissue necrosis), stagnant blood flow (from shock or cardiac arrest), or the presence of infectious agents leads to systemic activation of the coagulation system. A massive clotting cascade is triggered and leads to the formation of blood clots, possibly compromising the blood supply to major organs, and simultaneously to the exhaustion of platelets and coagulation factors, resulting in hemorrhaging.

Thus, DIC occurs when endothelial cells or monocytes are damaged by toxic substances. When these cells are injured, they release tissue factor on the surface of the cell, which in turn triggers the hemostasis system, activating a coagulation cascade. Thrombin accumulates rapidly, and fibrin is produced in large quantities and is deposited in the microvasculature, leading to blood clots throughout the capillary system. This clot formation leads rapidly to the depletion of platelets and coagulation factors throughout the body. Simultaneously, thrombin activates fibrinolytic pathways that release anticoagulants and dissolve the clots by turning them into fibrin split products, further contributing to uncontrollable bleeding. In chronic DIC, these events occur more slowly, allowing compensation to take place.

The diagnosis of DIC is based on clinical signs and laboratory findings. In acute DIC, the symptoms include multiple bleeding sites, the development of petechiae on the skin, ecchymoses of the skin and mucous membranes, visceral hemorrhaging, and the development of ischemic tissue. In chronic DIC, symptoms will include deep vein or arterial thrombosis or embolism, superficial venous thrombosis (especially in the absence of varicose veins), multiple and simultaneous thrombus sites, or serial thrombotic episodes. Laboratory findings indicative of DIC are decreased platelet count, prolonged prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time along with decreased fibrinogen levels and increased fibrin-fibrinogen degradation product (FDP) levels. Peripheral smears will show the presence of schistocytes (fragments of red blood cells).

Treatment and Therapy

The treatment of either the acute or the chronic form of DIC is based on the etiology and pathophysiology of the underlying clinical condition. Aside from the treatment of the underlying disorder, acute DIC requires aggressive treatment of the bleeding through the use of anticoagulants (such as heparin or antithrombin III) and antifibrinolytics (aminocaproic acid or tranexamic acid) as well as the administration of blood products, including fresh frozen plasma, cryoprecipitate, red blood cells, and platelets. The prognosis is determined by the underlying condition that led to DIC as well as the severity of the DIC. Follow-up care for those who survive is provided by a primary physician, for the underlying disorder, and by a hematologist.

Perspective and Prospects

Historically, disseminated intravascular coagulation has always been considered a secondary disease resulting as a consequence of some underlying disorder. Thus, DIC has always referred to the secondary activation of the coagulation system as a result of an underlying problem. The condition occurs with equal frequency in males and females and does not appear to be related to age.

While DIC is generally categorized, treated, and evaluated based on the pathophysiology of the underlying disorder, researcher Rodger L. Bick has proposed a DIC scoring system to assess the severity of the coagulation disorder as well as the effectiveness of the treatment modalities. New treatment modalities, such as the use of recombinant activated protein C, are being investigated in large multicenter clinical trials.

Bibliography

A.D.A.M. Medical Encyclopedia. "Bleeding Disorders." MedlinePlus, February 28 2011.

Bick, Roger L. “Disseminated Intravascular Coagulation: Objective Criteria for Diagnosis and Management.” Medical Clinics of North America 78 (1994): 511–43.

Kasper, Dennis L., et al., eds. Harrison’s Principles of Internal Medicine. 16th ed. New York: McGraw-Hill, 2005.

Kellicker, Patricia Griffin. "Disseminated Intravascular Coagulation." HealthLibrary, April 11, 2013.

Lichtman, Marshall A., et al., eds. Williams Hematology. 7th ed. New York: McGraw-Hill, 2006.

National Heart, Lung, and Blood Institute. "What Is Disseminated Intravascular Coagulation?" National Institutes of Health, November 2, 2011.