Diagnostic Criteria for Disseminated Intravascular Coagulation (DIC)
The diagnosis of DIC requires using the International Society on Thrombosis and Haemostasis (ISTH) overt DIC scoring system, which diagnoses DIC when a score ≥5 points is achieved based on platelet count, prothrombin time, fibrinogen level, and fibrin-related markers. 1
ISTH Overt DIC Scoring System
| Parameter | Score | Range |
|---|---|---|
| Platelet count (×10⁹/L) | 2 | <50 |
| 1 | ≥50, <100 | |
| Fibrin-related markers (D-dimer/FDP) | 3 | Strong increase |
| 2 | Moderate increase | |
| Prothrombin time (PT) | 2 | ≥6 seconds prolongation (PT ratio >1.4) |
| 1 | ≥3 seconds, <6 seconds prolongation (PT ratio >1.2, ≤1.4) | |
| Fibrinogen (g/L) | 1 | <1.0 |
Key Laboratory Parameters in DIC
Normal laboratory ranges:
- Platelet count: 150-450 × 10^9/L
- Prothrombin time (PT/INR): 11-14 seconds / 0.9-1.1
- Fibrinogen: 2-4 g/L
- D-dimer: < 0.5 mg/L
DIC laboratory ranges:
- Platelet count: < 50 × 10^9/L
- Prothrombin time (PT/INR): > 14 seconds / > 1.1
- Fibrinogen: < 1.5 g/L
- D-dimer: > 0.5 mg/L
Important Clinical Considerations
DIC is not a primary disease but a pathophysiological process that accompanies various underlying conditions such as sepsis, trauma, malignancy, or obstetric complications 2, 1
The diagnosis should incorporate both laboratory findings and clinical information 3
Serial monitoring is essential as DIC is a dynamic process - a 30% or higher drop in platelet count may indicate subclinical DIC even without clinical manifestations 1
Different types of DIC exist based on clinical presentation:
- Bleeding type
- Organ failure type
- Massive bleeding type
- Non-symptomatic type 4
Additional Diagnostic Considerations
Endothelial injury is an essential component in DIC pathophysiology, although current diagnostic criteria do not include biomarkers for vascular endothelial injury 2
The ISTH also recommends screening for sepsis-induced coagulopathy (SIC) in patients with sepsis, which represents a compensated phase of DIC 2
SIC diagnostic criteria include platelet count, prothrombin time, and sequential organ failure assessment score 2
Common Pitfalls in DIC Diagnosis
Overlooking the dynamic nature of DIC - single laboratory measurements may be misleading 1
Misinterpreting normal coagulation screens - a normal PT/aPTT does not exclude DIC, especially in subclinical forms 1
Overdiagnosis of DIC in liver disease patients due to similar laboratory profiles 1
Relying solely on INR for non-warfarin patients can be misleading, as INR was designed specifically for warfarin monitoring 1
Failing to recognize that DIC is always secondary to an underlying disorder - identifying and treating the primary cause is essential for successful management 1, 3
Remember that prompt diagnosis using the ISTH scoring system followed by immediate treatment of the underlying condition is critical for improving outcomes in patients with DIC.