- Pathophysiology
- Widespread systemic activation of the coagulation cascade, leading to a “thrombo-hemorrhagic” state.
- Pathologic generation of excess thrombin and fibrin in circulation.
- Phase 1 (Thrombotic): Massive, diffuse microthrombi formation in small and mid-sized vessels. This consumes platelets and coagulation factors.
- Phase 2 (Hemorrhagic): Depletion of platelets and factors leads to a consumption coagulopathy. Simultaneously, excess plasmin is generated, leading to fibrinolysis, which breaks down clots.
- The resulting fibrin degradation products (FDPs) interfere with platelet function and fibrin polymerization, worsening the bleeding.
- Etiology (Always secondary to another process)
- Sepsis (especially Gram-negative bacteria)
- Trauma (especially neurotrauma, burns, fat embolism)
- Obstetric complications (amniotic fluid embolism, abruptio placentae, HELLP syndrome)
- Pancreatitis (acute)
- Malignancy (especially APML/M3 AML, adenocarcinomas)
- Acute hemolytic transfusion reaction
- Kasabach-Merritt syndrome (giant hemangioma)
- Envenomation (snake bites)
- Clinical Features
- Bleeding: Oozing from IV sites, catheters, mucosal surfaces (gingiva, GI). Can be widespread and severe. Bleeding from ≥3 unrelated sites is highly suggestive.
- Thrombosis: Can lead to end-organ damage and multi-organ dysfunction syndrome (MODS).
- Renal: Oliguria, hematuria, acute kidney injury.
- Pulmonary: Dyspnea, hypoxemia, ARDS.
- CNS: Delirium, coma, focal neurologic deficits.
- Skin: Petechiae, ecchymosis, purpura fulminans, necrosis/gangrene.
- Chronic DIC: More common with solid tumors; often presents with thrombosis (e.g., DVT, PE) rather than bleeding.
- Diagnostics
- No single test is diagnostic; based on clinical picture and lab findings trending over time.
- Hallmark Lab Findings:
- Platelets: ↓ Thrombocytopenia (consumption)
- Coagulation Times: ↑ PT, ↑ PTT (consumption of factors)
- Fibrinogen: ↓ Low fibrinogen (consumption)
- Fibrinolysis Markers: ↑ D-dimer, ↑ FDPs (breakdown of fibrin clots)
- Peripheral Smear: Microangiopathic hemolytic anemia (MAHA) with schistocytes (fragmented RBCs) due to shearing in thrombosed small vessels.
- Differential Diagnosis
- Thrombotic Thrombocytopenic Purpura (TTP) / Hemolytic Uremic Syndrome (HUS): Also show MAHA and thrombocytopenia, but PT/PTT are typically normal.
- Severe Liver Disease: Can cause ↑PT/PTT and ↓fibrinogen due to decreased synthesis. D-dimer is usually less elevated than in DIC. Factor VIII is low in DIC but normal/high in liver disease (as it’s produced by endothelial cells).
- Treatment
- Treat the underlying cause: This is the most crucial step (e.g., antibiotics for sepsis, delivery for obstetric causes).
- Supportive care:
- Transfuse blood products based on clinical need (i.e., active bleeding), not just to correct lab values.
- Platelets: Transfuse for severe thrombocytopenia (<50,000/µL) with bleeding.
- Fresh Frozen Plasma (FFP): Replaces consumed clotting factors if bleeding with prolonged PT/PTT.
- Cryoprecipitate: Used to replace fibrinogen if levels are critically low (<100 mg/dL) and bleeding is present.
- Anticoagulation (Heparin): Rarely used in acute DIC due to bleeding risk. May be considered in cases dominated by thrombosis (e.g., chronic DIC with malignancy).
- Complications
- Multi-organ failure (renal, hepatic, respiratory)
- Life-threatening hemorrhage (e.g., intracerebral, GI)
- Limb ischemia and gangrene
- Shock and death (high mortality rate)