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How does disseminated intravascular coagulation cause both clotting and bleeding?

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Fibrin in blood clotting — bleeding and blood clotting Red blood cells (erythrocytes) trapped in a mesh of fibrin threads. Fibrin, a tough, insoluble protein formed after injury to the blood vessels, is an essential component of blood clots.

Disseminated intravascular coagulation (DIC) is a complex, acquired disorder characterized by the paradoxical presence of both widespread clotting and severe bleeding.1

The condition begins when an underlying trigger—such as severe tissue injury, infection, or malignancy—causes the systemic activation of the body's coagulation system. This leads to the formation of numerous small blood clots throughout the body's vasculature.1

The transition to a bleeding state occurs because this intense, uncontrolled clotting process rapidly consumes the available platelets and essential coagulation factors faster than the body can replace them. Furthermore, the body’s fibrinolytic system—which is designed to dissolve clots—becomes overactive in response to the widespread clotting. This activation leads to the destruction of fibrinogen and existing fibrin clots. The resulting depletion of clotting components leaves the blood unable to form necessary clots at sites of injury, ultimately resulting in a severe bleeding disorder.1