What are the diagnostic criteria and management strategies for Disseminated Intravascular Coagulation (DIC) in patients with high-risk conditions, such as severe sepsis, trauma, or cancer, presenting with signs of bleeding or clotting?

Diagnosis of Disseminated Intravascular Coagulation (DIC)

Use the ISTH overt-DIC scoring system (≥5 points) for definitive diagnosis in patients with suspected DIC, incorporating platelet count, PT prolongation, fibrin-related markers (D-dimer/FDP), and fibrinogen levels. 1

Core Diagnostic Criteria: ISTH Overt-DIC Score

The ISTH overt-DIC diagnostic criteria remain the gold standard for identifying decompensated coagulopathy 1:

• Platelet count: 2 points if <50×10⁹/L; 1 point if ≥50 but <100×10⁹/L 1
• D-dimer/FDP elevation: 3 points for strong increase; 2 points for moderate increase 1
• Prothrombin time prolongation: 2 points if ≥6 seconds prolonged; 1 point if ≥3 but <6 seconds 1
• Fibrinogen level: 1 point if <1.0 g/L 1
• Total score ≥5 indicates overt DIC 1

Two-Step Sequential Screening Approach

For septic patients, first screen with the ISTH Sepsis-Induced Coagulopathy (SIC) score to identify earlier-phase coagulopathy before progression to overt DIC. 1, 2

Step 1: SIC Screening (Score ≥4 indicates SIC)

• Platelet count: 2 points if <100×10⁹/L; 1 point if ≥100 but <150×10⁹/L 1
• PT ratio: 2 points if >1.4; 1 point if >1.2 but ≤1.4 1
• SOFA score: 2 points if ≥2; 1 point if =1 1

Step 2: Overt-DIC Assessment

• Apply the full overt-DIC criteria (above) to patients with SIC or worsening clinical status 1, 2
• Repeat screening on ICU admission and 2 days later—sequential screening is associated with lower mortality 1, 2

Essential Laboratory Tests

Core Panel for Diagnosis

• Complete blood count with platelet count: A ≥30% drop in platelets is diagnostic of subclinical DIC even when absolute values remain normal 3, 4
• PT and aPTT: May be prolonged, though normal values do not exclude DIC (only abnormal in ~50% of septic DIC cases) 3
• Fibrinogen: Typically decreased due to consumption, but may remain within normal range in early or subclinical DIC 3
• D-dimer: Elevated, indicating fibrinolysis; highly sensitive for DIC 3

Confirmatory Tests

• Factor VIII and von Willebrand Factor levels: Low or declining levels confirm consumptive coagulopathy 3
• Antithrombin levels: Declining levels suggest consumption, particularly useful in patients with renal failure 3
• Soluble fibrin monomer: Suggests thrombin presence and is more specific for DIC than stable cirrhotic coagulopathy 3

Critical Diagnostic Principles

Dynamic Monitoring is Essential

DIC is a rapidly evolving process—trend analysis over hours to days is more diagnostically important than single absolute values. 3

• Serial measurements showing dynamic deterioration distinguish DIC from stable chronic coagulopathies like cirrhosis 3
• Monitor frequency ranges from daily in acute severe DIC to monthly in chronic stable DIC 3
• Coagulation assays taken in isolation should be interpreted with extreme caution 3

Clinical Context is Mandatory

DIC diagnosis requires both laboratory abnormalities AND an appropriate underlying clinical condition (sepsis, trauma, malignancy, obstetric complications). 1

The ISTH defines DIC as "an acquired syndrome characterized by intravascular activation of coagulation with loss of localization arising from different causes that can originate from and cause damage to the microvasculature, producing organ dysfunction" 1

Common Diagnostic Pitfalls

• Normal PT/aPTT does not rule out DIC—these may remain normal in subclinical or early cancer-associated DIC 3
• Normal platelet count can be misleading in patients with initially elevated counts; focus on the trend (≥30% drop) rather than absolute values 3
• Liver disease mimics DIC but typically lacks the rapid dynamic changes characteristic of DIC; serial measurements showing deterioration suggest DIC superimposed on cirrhosis 3
• Endothelial dysfunction is central to DIC pathogenesis but current diagnostic criteria do not include endothelium-related markers despite their importance 1

DIC Subtypes and Their Diagnostic Patterns

Procoagulant DIC (Thrombosis-Predominant)

• Common in pancreatic cancer and adenocarcinomas 2, 4
• Presents with arterial ischemia, venous thromboembolism, or microvascular thrombosis 2
• Laboratory pattern: thrombocytopenia with thrombotic complications despite prolonged coagulation times 3

Hyperfibrinolytic DIC (Bleeding-Predominant)

• Typical of acute promyelocytic leukemia and metastatic prostate cancer 2, 4
• Presents with widespread bleeding from multiple sites 2
• Laboratory pattern: severe hypofibrinogenemia, markedly elevated D-dimer, profound thrombocytopenia 3

Subclinical DIC

• Laboratory abnormalities without obvious clinical bleeding or thrombosis 4
• Diagnosed by ≥30% platelet drop, elevated D-dimer, and mild coagulation factor consumption 3, 4
• May progress to overt DIC without treatment of underlying condition 1

Monitoring Frequency Based on Clinical Severity

• Daily monitoring: Acute severe DIC with active bleeding or rapid clinical deterioration 3
• Every 2-3 days: Stable ICU patients with diagnosed DIC 3
• Weekly: Hospitalized patients with chronic DIC (e.g., cancer-associated) 3
• Monthly: Outpatients with stable subclinical DIC 3