What is the workup for Disseminated Intravascular Coagulation (DIC)?

Workup for Disseminated Intravascular Coagulation (DIC)

The diagnostic workup for DIC should include serial laboratory testing of platelet count, prothrombin time (PT/INR), fibrinogen, and D-dimer, with dynamic changes in these parameters being the hallmark of DIC. 1

Initial Laboratory Assessment

The cornerstone of DIC diagnosis involves the following laboratory tests:

1. Complete Blood Count (CBC)

   • Focus on platelet count (thrombocytopenia is common in DIC)
   • Serial measurements to detect declining trends

2. Coagulation Studies

   • Prothrombin Time (PT/INR) - typically prolonged
   • Activated Partial Thromboplastin Time (aPTT) - typically prolonged
   • Fibrinogen level - typically decreased
   • D-dimer or Fibrin Degradation Products (FDPs) - markedly elevated

3. Additional Confirmatory Tests

   • Factor VIII and von Willebrand Factor (vWF) levels - low or declining levels confirm consumptive process 1
   • Antithrombin (AT) activity - declining levels suggest consumptive coagulopathy 1
   • Soluble fibrin - useful marker for coagulation activation 1

ISTH DIC Scoring System

The International Society on Thrombosis and Haemostasis (ISTH) scoring system provides an objective measurement of DIC 2, 3:

Parameter	0 points	1 point	2 points	3 points
Platelet count	>100 × 10^9/L	50-100 × 10^9/L	<50 × 10^9/L	-
D-dimer/FDPs	No increase	Moderate increase	Strong increase	-
PT prolongation	<3 seconds	3-6 seconds	>6 seconds	-
Fibrinogen	>1.0 g/L	<1.0 g/L	-	-

• Score ≥5: Overt DIC
• Score <5: Suggestive of non-overt DIC (repeat testing in 24 hours)

Critical Diagnostic Considerations

1. Identify Underlying Cause

   • DIC is always secondary to an underlying condition 2, 4
   • Common causes include:
     • Severe infections/sepsis (most common)
     • Malignancy (especially pancreatic, adenocarcinomas)
     • Obstetric complications
     • Trauma
     • Vascular disorders

2. Serial Testing

   • Single measurements are insufficient; DIC is a dynamic process 1
   • Rapid changes in hemostatic parameters (hours to days) are characteristic of DIC 1, 2
   • Repeat testing at 24-hour intervals to monitor progression

3. Differential Diagnosis

   • Liver disease (can have similar laboratory findings)
   • Distinguish DIC from liver disease by:
     • Dynamic changes in parameters (DIC) vs. stable abnormalities (liver disease) 1
     • Presence of underlying trigger (necessary for DIC diagnosis) 1
     • Multiorgan failure from micro/macrovascular thrombi (in DIC) 1

Specialized Considerations

1. Endothelial Dysfunction Assessment

   • Antithrombin activity and von Willebrand factor can serve as markers for endothelial injury 1, 2
   • The platelet count/vWF antigen ratio is a strong prognostic marker in DIC 2

2. DIC Subtypes Recognition

   • Procoagulant DIC: Excess thrombin generation causing thrombosis 1, 2
   • Hyperfibrinolytic DIC: Dominated by activation of fibrinolytic system 1, 2
   • Subclinical DIC: No obvious clinical manifestations but laboratory markers present 1, 2

3. Clinical Correlation

   • Laboratory findings must be interpreted in clinical context
   • Look for:
     • Bleeding manifestations (mucosal bleeding, petechiae)
     • Thrombotic manifestations (organ dysfunction, skin necrosis)
     • Evidence of microvascular thrombosis (organ failure)

Common Pitfalls to Avoid

1. Single Time-Point Assessment

   • DIC is a dynamic process; single measurements can be misleading
   • Serial testing is essential to capture the evolving nature of DIC 1, 3

2. Ignoring the Underlying Condition

   • Always search for and address the underlying trigger 4
   • Patients may have more than one cause of DIC 4

3. Overdiagnosis in Liver Disease

   • Patients with liver disease often meet laboratory criteria for DIC without having it 1
   • Look for dynamic changes and clinical correlation

4. Delayed Recognition

   • Early identification improves outcomes 1
   • Consider DIC screening on ICU admission and repeat 2 days later 1

By systematically applying this diagnostic approach with serial laboratory testing and careful clinical correlation, clinicians can effectively diagnose DIC and initiate appropriate management to improve patient outcomes.