Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is a life-threatening derangement of clotting regulation that results in widespread clot formation. Multiple organ systems are affected, including the skin where thrombosed vessels result in necrosis. Damage to thrombosed vessels results in ecchymoses, while consumption of platelets in widespread clotting results in thrombocytopenia and petechiae. DIC most often occurs as a result of bacterial sepsis. Other causes include malignancy, amniotic fluid embolism, and massive trauma.

The appearance of the lesions is important in distinguishing it from other causes of ecchymoses, such as actinic purpura. The purpura of DIC is usually described as "stellate" with a necrotic center that appears dark gray. Although most hemorrhagic lesions of DIC are macules, palpable purpura is sometimes present due to localized edema. Various other lesions and physical signs may be present, including hemorrhagic bullae, mucosal bleeding, and bleeding from around puncture sites or intravenous lines (bleeding supervenes as clotting factors and platelets are consumed; DIC is a "consumptive coagulopathy".)

With what can it be confused?

The lesions of DIC are jagged or stellate, often with areas of necrosis. Lesions that result from blood vessel fragility (e.g. actinic purpura) have regular margins, are round or oval, and do not exhibit necrosis. Patients with DIC are also usually quite sick. Distinguishing DIC from vasculitis may require a biopsy if the lesion is palpable.

How is it diagnosed?

Patients are usually systemically ill, and are often in extremis. Fever is often present, and shock frequently intervenes. A history of malignancy should be sought. See above for features that distinguish DIC from other causes of purpura. Since DIC is a "consumptive coagulopathy" there is a decrease in platelets and clotting factors. Platelets and fibrinogen will be low; prothrombin time and activated partial thromboplastin time will be prolonged; and D-dimers or fibrin degradation products will be present, indicating the ongoing breakdown of clot. Biopsy is sometimes necessary to distinguish DIC from vasculitis; in DIC there will be evidence of intravascular thrombi, blood vessel necrosis, possibly dermal or epidermal necrosis, extravasation of blood into the dermis, and little associated inflammation.

How is it treated?

The underlying condition must be treated emergently. Treatment of DIC remains controversial, and an experienced intensivist should be consulted. Generally, platelets or plasma should be infused only if there is active bleeding, if an invasive procedure is required, or if the platelet count falls below 10,000-20,000. In the past it was thought that adding platelets or clotting factors "adds fuel to the fire". This has never been corroborated by clinical evidence. Specific factor deficiencies can be replaced with concentrates. Some advocate heparin to inhibit the coagulation cascade, but the effectiveness of this maneuver has not yet been conclusively demonstrated. The use of recombinant activated protein C (Drotrecogin alpha; Ely Lilly) has been shown in pivotal clinical trials to reduce sepsis-related mortality and may be beneficial in the treatment of DIC.

What is the prognosis?

The mortality rate reported in severe sepsis in the Drotrecogin alfa clinical trial was 30.8% in the placebo group and 24.7% in the treatment group. DIC in the context of septic abortion and clostridial infection is reported to have a mortality rate of 50%. The presence of DIC in the setting of major trauma, is associated with a doubling in the mortality rate.

Image links

University of California, San Diego: Sepsis induced DIC leading to gangrene

University of Pittsburgh School of Medicine, Department of Pathology: Case 53 -- Fever, Purpura and Hypotension