What are the criteria for diagnosing Disseminated Intravascular Coagulation (DIC)?

Diagnostic Criteria for Disseminated Intravascular Coagulation (DIC)

The diagnosis of DIC requires an underlying causative condition plus a score of ≥5 points on the ISTH overt DIC scoring system, which incorporates platelet count, fibrin-related markers (D-dimer/FDP), prothrombin time, and fibrinogen level. 1, 2

Essential Prerequisite: Identify the Underlying Trigger

DIC is never a primary disease but always secondary to an underlying condition. 3 The most common triggers include:

• Sepsis (most common cause) 3
• Malignancy (particularly acute promyelocytic leukemia, pancreatic cancer, and adenocarcinomas) 2, 3
• Trauma and major surgery 3
• Obstetric complications 3, 4

Without an underlying causative condition, DIC cannot be diagnosed regardless of laboratory abnormalities. 3

ISTH Overt DIC Scoring System (≥5 Points = DIC)

This is the validated diagnostic standard recommended by international guidelines. 1, 2

Platelet Count:

• 2 points: <50 × 10⁹/L 1, 2
• 1 point: ≥50 to <100 × 10⁹/L 1, 2

Fibrin-Related Markers (D-dimer or FDP):

• 3 points: Strong increase 1, 2
• 2 points: Moderate increase 1, 2

Prothrombin Time (PT):

• 2 points: ≥6 seconds prolongation OR PT ratio >1.4 1, 2
• 1 point: ≥3 to <6 seconds prolongation OR PT ratio >1.2 to ≤1.4 1, 2

Fibrinogen:

• 1 point: <100 mg/dL (or <1.0 g/L) 1, 2

Total score ≥5 points confirms overt DIC. 1, 2

Sepsis-Induced Coagulopathy (SIC) Scoring System (≥4 Points = SIC)

For septic patients specifically, the SIC criteria enable earlier detection before progression to overt DIC. 1, 2 This is clinically important because patients with advanced overt DIC may have illness progression no longer amenable to anticoagulant therapy. 1

Platelet Count:

• 2 points: <100 × 10⁹/L 2
• 1 point: ≥100 to <150 × 10⁹/L 2

PT Ratio:

• 2 points: >1.4 2
• 1 point: >1.2 to ≤1.4 2

SOFA Score (Sequential Organ Failure Assessment):

• 2 points: ≥2 1, 2
• 1 point: 1 2

Total score ≥4 points confirms sepsis-induced coagulopathy. 1, 2

Critical Diagnostic Pitfalls to Avoid

Normal Coagulation Screens Do NOT Rule Out DIC:

• PT and aPTT may remain normal in approximately 50% of septic DIC cases and in cancer-associated DIC. 5, 3
• A 30% or greater drop in platelet count is diagnostic of subclinical DIC even when absolute platelet values remain in the normal range. 5, 3

Trend Monitoring is More Important Than Static Values:

• Declining trends in platelet count, fibrinogen, and coagulation factors are more diagnostically important than single measurements. 5
• Repeat laboratory testing is essential to assess the dynamically changing scenario. 2, 6

D-dimer Has the Highest Sensitivity:

• A normal D-dimer level effectively rules out DIC (sensitivity 91-100%), making it the single most useful screening test to exclude the diagnosis. 5

Confirmatory Tests for Difficult Cases

When the diagnosis is uncertain despite scoring systems:

• Factor VIII and von Willebrand factor: Low or declining levels confirm consumptive coagulopathy in DIC, whereas these are normal or elevated in chronic liver disease. 5, 3
• Antithrombin levels: Low or declining levels support DIC diagnosis. 5

Monitoring Frequency Based on Clinical Stability

The frequency of repeat testing depends on patient stability: 3

• Daily monitoring: Acute DIC, active bleeding, or rapid deterioration 3
• More frequent monitoring: When initiating treatment 3
• Monthly monitoring: Stable patients with chronic conditions 3

Screening for overt DIC on ICU admission and repeating 2 days later is associated with lower mortality, suggesting that DIC screening itself may lead to improved outcomes. 1

Alternative Diagnostic Criteria

While the ISTH overt DIC criteria are the international standard, other scoring systems exist:

• Japanese Association for Acute Medicine (JAAM) criteria: Display high sensitivity for DIC 7
• Japanese Ministry of Health and Welfare (JMHW) criteria: Still used in Japan 7

All three diagnostic criteria (ISTH, JAAM, JMHW) correlate with poor patient outcomes, with odds ratios for death ranging from 1.88 to 2.55. 7 The ISTH overt-DIC criteria display the highest specificity for DIC. 7