Disseminated Intravascular Coagulation (DIC)

Overview

• Systemic activation of coagulation that can lead to thrombotic complications (organ impairment) or bleeding (through consumption of clotting factors and platelets).
• Always secondary to an underlying condition such as infection or cancer.
• May be acute or chronic (chronic forms are seen with cancer or vascular malformations).
• Characterized by coagulation abnormalities: variable prolongation of PT and aPTT, low or falling fibrinogen (may be normal or high as an acute-phase reactant, esp. sepsis), elevated D-dimer, and thrombocytopenia.

Pathophysiology

• Trigger (infection, cancer, trauma) → activation of the coagulation cascade.
• Consumption of platelets and clotting factors (↓ platelets, ↓ clotting factors) plus variable fibrinolysis (hyperfibrinolytic in APL and obstetric or cancer cases; suppressed in sepsis-DIC via high PAI-1); fibrinogen is consumed but may be normal or elevated as an acute-phase reactant.
• Microvascular thrombosis driven by endothelial damage and neutrophil activation, which produces organ impairment; simultaneous consumption produces bleeding.
• The fibrinolytic component reflects increased tPA (from endothelial cells) or uPA (from cancer cells), leading to consumption and decreased alpha-2-antiplasmin.

Causes

• Sepsis / infection: activation and consumption of clotting factors by microbes.
• Malignancy, especially acute promyelocytic leukemia (APL, hyperfibrinolytic DIC); also mucin-producing adenocarcinomas and other cancers.
• Obstetric complications.
• Trauma (including major tissue injury and burns).

Acute vs chronic DIC

Laboratory findings

• Thrombocytopenia (low platelets).
• Low or falling fibrinogen (normal fibrinogen does not exclude DIC).
• Elevated D-dimer and fibrin degradation products (FDPs).
• Prolonged PT and aPTT (variable).
• Schistocytes on the peripheral smear.

ISTH scoring

• Overt DIC is scored with the ISTH DIC criteria; the standard published ISTH overt DIC scoring components are shown below.
• ISTH 2025 update: DIC redefined to include an early, often asymptomatic phase with disease-specific criteria; in sepsis use the SIC score (platelets 100 to 149 = 1, <100 = 2; INR >1.2 to 1.4 = 1, >1.4 = 2; 4-component SOFA 1 = 1, ≥2 = 2; SIC if total ≥4 with platelet plus INR points >2). The overt score identifies late-phase DIC.

Management

• Treat the underlying condition (the cornerstone).
• Active bleeding or need for an invasive procedure: platelet transfusion to keep platelets >50,000/mcL in active bleeding or before an invasive procedure (higher if procedure-specific); 30 to 50,000/mcL is APL-specific; plasma for active bleeding or before a necessary invasive procedure when PT/aPTT are significantly prolonged (e.g., ratio >1.5x), guided by bleeding rather than a fixed near-normal PT target; cryoprecipitate or fibrinogen concentrate for bleeding with hypofibrinogenemia (fibrinogen <150 mg/dL, 1.5 g/L); antifibrinolytic treatment only in the case of excessive hyperfibrinolysis.
• No major bleeding or thrombosis: prophylactic heparin (unfractionated or low molecular weight).
• Overt thromboembolism and/or organ failure related to thrombosis: therapeutic anticoagulation (e.g., unfractionated heparin).
• Caution: routine antifibrinolytics (e.g., TXA) are generally avoided in DIC because they can precipitate thrombosis; reserve for documented excessive hyperfibrinolysis with bleeding.