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Chapter 86: Disseminated Intravascular Coagulation

INTRODUCTION

  • Disseminated intravascular coagulation (DIC) is a syndrome that is characterized by systemic intravascular activation of coagulation, leading to fibrin deposition in the microvasculature and small-midsize vessels, thereby contributing to organ dysfunction. Simultaneously, ongoing consumption of platelets and coagulation factors lead to thrombocytopenia and impaired coagulation and may result in serious bleeding complications.

  • DIC never occurs by itself but is always secondary to an underlying cause. Table 86–1 lists the most frequently occurring disorders know to be associated with DIC.

TABLE 86–1CLINICAL CONDITIONS THAT MAY BE COMPLICATED BY DIC
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TABLE 86–1 CLINICAL CONDITIONS THAT MAY BE COMPLICATED BY DIC
Sepsis/severe infection
Trauma

Malignancy

 Solid tumors

 Acute leukemia

Obstetrical conditions

 Amniotic fluid embolism

 Abruptio placentae

 HELLP syndrome

Vascular abnormalities

 Kasabach-Merritt syndrome

 Other vascular malformations

 Aortic aneurysms
Severe allergic/toxic reactions
Severe immunologic reactions (e.g., transfusion reaction)
Heatstroke

HELLP, hemolysis, elevated liver enzymes, and low platelet count.

Source: Williams Hematology, 8th ed, Chap. 130, Table 130–1, p. 2105.

PATHOGENESIS

  • The pathogenesis of DIC is diagrammed in Fig. 86–1.

  • Exposure of blood to tissue factor appears to be the principal mechanism of activation of coagulation. Tissue factor may be expressed by mononuclear cells or by the endothelium.

  • Other stimuli include activation of factor Xa by a cancer procoagulant, snake envenomation, and tissue/cellular debris in patients with massive trauma or pancreatitis.

  • Activation of coagulation is insufficiently balanced by physiologic anticoagulant pathways (e.g., antithrombin, protein C system) and a downregulation of endogenous fibrinolysis due to high levels of the fibrinolysis inhibitor plasminogen activator inhibitor type 1 (PAI-1).

FIGURE 86–1

Schematic presentation of pathogenetic pathways involved in the activation of coagulation in DIC. In DIC, both perturbed endothelial cells and activated mononuclear cells may produce proinflammatory cytokines that mediate coagulation activation. Activation of coagulation is initiated by tissue factor expression on activated mononuclear cells and endothelial cells. In addition, downregulation of physiologic anticoagulant mechanisms and inhibition of fibrinolysis by endothelial cells further promote intravascular fibrin deposition. PAI-1, plasminogen-activator inhibitor type 1.

Source: Williams Hematology, 8th ed, Chap. 130, Fig. 130–1, p. 2102.

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CLINICAL FEATURES

  • Clinical features are related to the underlying disorder, to the DIC, or both.

  • Bleeding manifestations have been observed in about 25 percent of cases in several series.

  • Persistent bleeding from venipuncture sites or other skin wounds occurs frequently.

  • Hemorrhage may be life-threatening.

  • Extensive organ dysfunction may be induced by microvascular thrombi, or by venous and/or arterial thromboembolism.

  • Organ dysfunction may manifest as acute renal failure (renal cortical ischemia and acute tubular necrosis occur frequently), hepatic dysfunction, and respiratory insufficiency due to acute respiratory distress syndrome (ARDS).

  • Coma, delirium, focal neurologic symptoms, and signs of meningeal irritation may occur because of thrombosis or hemorrhage in the cerebral vasculature.

  • Mortality rates range from 30 ...

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