Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is an acquired syndrome of systemic activation of coagulation. Widespread generation of thrombin leads to fibrin deposition in small vessels and consumption of platelets and clotting factors. The result is a paradoxical combination: microvascular thrombosis that can impair organ perfusion alongside bleeding from depletion of the very factors being consumed. DIC is always secondary to an underlying condition such as sepsis, major trauma, malignancy, or obstetric complications.

Definition

Disseminated intravascular coagulation is an acquired disorder characterized by widespread activation of coagulation, leading to intravascular fibrin formation and consumption of platelets and coagulation factors, which together can cause both microvascular thrombosis and bleeding; it occurs as a complication of an underlying disease.

Scope

This entry covers the pathophysiology of systemic coagulation activation, the simultaneous risks of thrombosis and bleeding, the role of fibrinolysis, and the underlying triggers. It treats DIC as a reference topic in hemostasis and does not provide diagnostic scoring thresholds or management instructions.

Core questions

• How can the same syndrome cause both thrombosis and bleeding at the same time?
• What underlying conditions trigger systemic activation of coagulation?
• How do consumption of factors and activation of fibrinolysis combine to define the laboratory picture?

Key concepts

• Systemic activation of coagulation
• Tissue factor-driven thrombin generation
• Consumption of platelets and clotting factors
• Microvascular fibrin thrombosis
• Secondary fibrinolysis and fibrin degradation products
• Underlying trigger (sepsis, trauma, malignancy, obstetric)
• Bleeding-versus-thrombosis phenotype

Mechanisms

DIC begins when an underlying disorder exposes the circulation to tissue factor or other procoagulant stimuli, driving widespread thrombin generation. Thrombin converts fibrinogen to fibrin throughout the microvasculature, while natural anticoagulant pathways are simultaneously impaired, favoring continued clotting. This consumes platelets and coagulation factors faster than they can be replaced, so the patient may bleed even as small vessels are occluded by fibrin. Fibrinolysis is activated secondarily, generating fibrin degradation products and sometimes contributing further to bleeding. The net clinical phenotype — predominantly thrombotic, predominantly hemorrhagic, or both — depends on the trigger and its tempo, as reviewed by Levi and Ten Cate (1999) and Gando et al. (2016).

Clinical relevance

The concept of consumption explains why DIC produces a characteristic constellation of falling platelets, prolonged clotting times, low fibrinogen, and elevated fibrin degradation products, and why it is always evaluated together with its underlying cause. This entry describes the syndrome for reference; scoring systems and management of DIC and its trigger follow specialist guidelines and are outside its scope.

Epidemiology

DIC is not a primary disease but a complication, most often of sepsis, severe trauma, advanced malignancy, and obstetric emergencies such as placental abruption or amniotic fluid embolism. Its frequency therefore tracks the incidence of these conditions, and it is a recognized marker of severity in critically ill patients, as discussed by Gando et al. (2016).

Evidence & guidelines

Guidance such as the British Society for Haematology guidelines for the diagnosis and management of disseminated intravascular coagulation (Levi et al., 2009) frames the use of composite scoring and the principle of treating the underlying cause. This entry references such guidelines for orientation rather than reproducing their thresholds or recommendations.

History

The recognition that coagulation could be activated systemically, consuming clotting factors and causing both thrombosis and bleeding, emerged through twentieth-century studies of defibrination in obstetric and septic catastrophes. The syndrome became formalized as disseminated intravascular coagulation, and later work on tissue factor, natural anticoagulants, and standardized scoring refined its diagnosis, as synthesized by Levi and Ten Cate (1999).

Key figures

• Marcel Levi
• Hugo Ten Cate
• Satoshi Gando
• Cheng-Hock Toh

Seminal works

• levi-tencate-1999
• gando-2016

Frequently asked questions

How can disseminated intravascular coagulation cause both clotting and bleeding?

Systemic activation of coagulation deposits fibrin in small vessels (thrombosis) while consuming platelets and clotting factors faster than they are replaced, leaving too few to maintain normal hemostasis (bleeding). Secondary fibrinolysis can add to the bleeding tendency.

Is disseminated intravascular coagulation a disease on its own?

No. DIC is always secondary to an underlying condition such as sepsis, major trauma, cancer, or an obstetric emergency. It is evaluated and understood in the context of that trigger.