Disseminated Intravascular Coagulation

Etiology and Risk Factors

DIC always arises as a complication of another condition (Norris, 2020). Associated conditions include (Davoren & Hsu, 2019; Norris, 2020):

• Infection: Gram-negative sepsis, meningococcemia, rickettsial infection, malaria, and acute viral infection
• Obstetric complications: Placental abruption, amniotic fluid embolism, retained dead fetus, and preeclampsia or eclampsia
• Trauma and tissue injury: Massive trauma, burns, heat stroke, surgery with extracorporeal circulation, and snakebite
• Malignancy: Metastatic cancer and acute leukemia
• Shock: Septic shock and severe hypovolemic shock
• Hematologic: Acute hemolytic transfusion reaction

Epidemiology and Clinical Context

DIC occurs in patients who are already seriously ill. It is listed among the major complications of septic shock and of severe circulatory shock from any cause (Branan & Smith, 2026; Norris, 2020). Infection and inflammation are central to its pathogenesis, and the inflammatory cytokines released in these states are pivotal mediators (Norris, 2020).

Pathophysiology

DIC begins with unregulated thrombin generation and systemic fibrin formation. The trigger is usually tissue factor released from damaged tissue, necrotic placental tissue, amniotic fluid, or tumor cells, or expressed on endothelial cells in response to bacterial endotoxin. Endothelial injury from infection, hypoxia, acidosis, or temperature extremes adds to the drive (Norris, 2020).

Inflammatory cytokines, particularly tumor necrosis factor and interleukin-1, increase tissue factor expression on endothelial cells and decrease thrombomodulin, the endothelial receptor that allows thrombin to activate protein C. Levels of protein C, protein S, antithrombin, and tissue factor pathway inhibitor fall, and increased plasminogen activator inhibitor-1 impairs fibrinolysis. Endotoxin also inhibits protein C directly (Norris, 2020).

The consequences unfold as a loop (Davoren & Hsu, 2019; Norris, 2020):

• Widespread microthrombi occlude small vessels, causing tissue ischemia and organ dysfunction.
• Clot formation consumes platelets, fibrinogen, and other clotting factors faster than they can be replaced.
• Fibrinolysis is activated, and plasmin breaks fibrin into degradation products that have anticoagulant effects.
• Bleeding results from depleted platelets and factors and from the anticoagulant effect of fibrin degradation products.
• Red cells passing through partially occluded vessels are sheared, producing a hemolytic anemia with fragmented cells.

Clinical Manifestations

Although DIC begins with clotting, the acute presentation is usually dominated by bleeding (Norris, 2020):

• Petechiae and purpura
• Oozing from venipuncture, catheter, and surgical sites
• Mucosal bleeding
• Uncontrolled postpartum hemorrhage
• Severe hemorrhage

Microvascular thrombosis produces organ dysfunction (Norris, 2020):

• Acute kidney injury
• Respiratory failure
• Circulatory failure
• Gastrointestinal ulceration and bleeding
• Confusion, seizures, or coma

Diagnostic Evaluation

Clinical Context

DIC should be considered in any patient with sepsis, shock, major trauma, an obstetric complication, or malignancy who develops unexpected bleeding, thrombocytopenia, or organ dysfunction (Norris, 2020).

Laboratory Testing

Laboratory findings reflect consumption and fibrinolysis (Davoren & Hsu, 2019; Norris, 2020):

• Platelet count: Low or falling because of consumption in microthrombi.
• PT with international normalized ratio (INR) and aPTT: Usually both prolonged because factor depletion affects the pathways measured by both tests (Davoren & Hsu, 2019).
• Fibrinogen: Low or falling as it is converted to fibrin faster than it is produced.
• Fibrin degradation products and D-dimer: Elevated from plasmin breakdown of fibrin.
• Peripheral smear: Fragmented red cells from shearing in partially occluded vessels.
• Hemoglobin and hemolysis markers: Anemia from bleeding and red cell fragmentation (Davoren & Hsu, 2019; Huynh et al., 2026; Norris, 2020).

Additional Testing

Evaluation also targets the underlying cause and organ function, including blood cultures, lactate, renal and liver function, and arterial blood gas analysis (Branan & Smith, 2026; Wood, 2026). In shock, an INR above 1.5 or a platelet count below 50,000/μL is one marker of hematologic organ dysfunction (Wood, 2026).

Expected Findings

Findings that support DIC include (Davoren & Hsu, 2019; Norris, 2020):

• A serious underlying trigger
• Thrombocytopenia
• Prolonged PT/INR and aPTT
• Low fibrinogen
• Elevated fibrin degradation products and D-dimer
• Fragmented red cells on the smear
• Simultaneous bleeding and organ dysfunction

Differential Diagnosis

Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) also causes thrombocytopenia, fragmented red cells, and organ dysfunction, but results from ADAMTS13 deficiency and platelet-rich microthrombi. It requires emergency plasmapheresis (Norris, 2020). See Thrombocytopenia.

Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) causes thrombocytopenia with thrombosis in a patient receiving heparin, typically 5 to 10 days after exposure (Davoren & Hsu, 2019).

Liver Disease

Most coagulation factors are synthesized in the liver, so liver disease reduces factor production and can cause bleeding. Reduced thrombopoietin production and hypersplenism can also lower the platelet count (Davoren & Hsu, 2019; Norris, 2020).

Vitamin K Deficiency and Warfarin Effect

Vitamin K deficiency and warfarin reduce functional factors II, VII, IX, and X, prolonging the PT first, without consuming platelets or fibrinogen (Davoren & Hsu, 2019; Norris, 2020).

Dilutional Coagulopathy

Large-volume crystalloid resuscitation can dilute clotting factors and cause coagulopathy, especially during active bleeding (Wood, 2026).

Findings That Reduce Diagnostic Probability

Few laboratory findings exclude DIC by themselves. The following findings should lower its position in the differential or prompt evaluation for an alternative:

• A normal platelet count and fibrinogen make acute DIC less likely (Davoren & Hsu, 2019; Norris, 2020).
• Isolated prolongation of the PT with a normal platelet count suggests vitamin K deficiency, warfarin effect, or early liver disease (Davoren & Hsu, 2019).
• Thrombocytopenia with fragmented red cells, fever, neurologic changes, and renal dysfunction should raise concern for TTP, which requires different emergency treatment (Norris, 2020).
• The absence of a serious underlying illness should prompt reconsideration of the diagnosis (Norris, 2020).

Treatment and Management

Treat the Underlying Cause

Management has three aims: treat the underlying disorder, replace consumed clotting components, and prevent further activation of coagulation. Correcting the trigger is what ultimately stops the process (Norris, 2020).

Replacement Therapy

Replacement therapy includes (Norris, 2020):

• Fresh frozen plasma replaces clotting factors.
• Platelet transfusion replaces platelets.
• Cryoprecipitate provides concentrated fibrinogen.

Supportive Care

In sepsis-associated DIC, resuscitation with fluids and vasopressors to restore perfusion addresses the hypoxia and acidosis that sustain endothelial injury. Early antibiotics and source control treat the trigger (Branan & Smith, 2026).

Complications and Red Flags

Urgent escalation is required for:

• Active bleeding from multiple sites
• Uncontrolled postpartum hemorrhage
• Falling platelet count or fibrinogen in a critically ill patient
• New organ dysfunction, including oliguria, hypoxemia, or altered mentation
• Hypotension or rising lactate
• Signs of intracranial or gastrointestinal hemorrhage

Complications include multiple organ dysfunction syndrome and death (Norris, 2020).

Clinical Reasoning Priorities

The same patient can have ischemic organs and oozing intravenous sites because both result from coagulation activated so widely that it consumes the platelets and clotting factors needed for hemostasis. Blood products support hemostasis while the cause is corrected, and correcting the cause is what ends the process (Norris, 2020).

Look for the trigger in every case. Sepsis, shock, obstetric complications, trauma, and malignancy are the common triggers, and treatment of the trigger determines whether DIC resolves (Norris, 2020).

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References

Branan, T. N., & Smith, S. E. (2026). Sepsis and septic shock. In M. A. Chisholm-Burns, P. M. Malone, J. M. Kolesar, K. C. Lee, P. B. Bookstaver, & K. R. Matthias (Eds.), Pharmacotherapy principles & practice (7th ed.). McGraw Hill.

Davoren, J. B., & Hsu, G. (2019). Blood disorders. In G. D. Hammer & S. J. McPhee (Eds.), Pathophysiology of disease: An introduction to clinical medicine (8th ed.). McGraw-Hill Education.

Huynh, N. S., Cantrell, M., & Lee, J. C. (2026). Venous thromboembolism. In M. A. Chisholm-Burns, P. M. Malone, J. M. Kolesar, K. C. Lee, P. B. Bookstaver, & K. R. Matthias (Eds.), Pharmacotherapy principles & practice (7th ed.). McGraw Hill.

Norris, T. L. (2020). Porth’s essentials of pathophysiology (5th ed.). Wolters Kluwer.

Wood, G. C. (2026). Circulatory shock syndromes. In M. A. Chisholm-Burns, P. M. Malone, J. M. Kolesar, K. C. Lee, P. B. Bookstaver, & K. R. Matthias (Eds.), Pharmacotherapy principles & practice (7th ed.). McGraw Hill.