In disseminated intravascular coagulation (DIC), which of the following laboratory findings is most characteristic of the consumptive coagulopathy phase?

Explanation

## Disseminated Intravascular Coagulation (DIC): Laboratory Profile **Key Point:** DIC is a systemic disorder characterized by widespread activation of coagulation, leading to simultaneous thrombosis and consumption of clotting factors and platelets, resulting in a characteristic **consumptive coagulopathy** pattern. ### Pathophysiology of DIC 1. **Initiation phase** — tissue factor or endothelial damage triggers extrinsic pathway 2. **Amplification phase** — thrombin generation activates platelets and factor V 3. **Propagation phase** — intrinsic pathway amplifies coagulation 4. **Consumptive phase** — depletion of platelets, fibrinogen, and coagulation factors ### Laboratory Findings in DIC (Consumptive Phase) | Parameter | Finding | Mechanism | | --- | --- | --- | | Platelet count | **Decreased** | Consumption in microthrombi | | Fibrinogen | **Decreased** | Consumption and degradation | | PT/aPTT | **Prolonged** | Consumption of factors II, V, VII, X, VIII, IX | | D-dimer / FDP | **Markedly elevated** | Excessive fibrinolysis and plasmin generation | | Prothrombin time | **Prolonged** | Factor depletion | | Activated partial thromboplastin time | **Prolonged** | Factor depletion | | Antithrombin III | **Decreased** | Consumption by thrombin | | Fibrin monomer | **Elevated** | Ongoing thrombin generation | **High-Yield:** The **pentad of DIC** laboratory findings: 1. Thrombocytopenia (↓ platelets) 2. Hypofibrinogenemia (↓ fibrinogen) 3. Prolonged PT/aPTT (↓ factors) 4. Elevated D-dimer/FDP (↑ fibrinolysis) 5. Elevated fibrin monomer (↑ thrombin activity) **Mnemonic:** **"TFDC"** — **T**hrombocytopenia, **F**ibrinogen ↓, **D**-dimer ↑, **C**oagulation times ↑ **Clinical Pearl:** DIC is a medical emergency. Common triggers include sepsis (gram-negative bacteria most common), acute promyelocytic leukemia (APML), severe trauma, amniotic fluid embolism, and acute hemolytic transfusion reactions. The bleeding tendency in DIC is due to consumption of platelets and factors, not inhibitor formation. **Warning:** Early DIC may show normal or elevated fibrinogen (acute phase reactant) with elevated D-dimer alone — do not be falsely reassured. Serial monitoring is essential. Chronic DIC (e.g., in malignancy) may show only mild thrombocytopenia and elevated D-dimer without severe factor depletion.