Disseminated Intravascular Coagulation (DIC)

Pathophysiology

  • Trigger:
    • Uncontrolled systemic release of Tissue Factor (TF).
  • TF location
    • Skin
    • Adventitia
    • Epithelial–mesenchymal interface
  • Loss of vascular integrity → TF enters circulation → exposed to platelets.
  • TF binds Factor VII → Factor VIIa activation.
  • Extrinsic coagulation cascade activation.
  • Continuous excessive thrombin generation.
  • Consumption of platelets and clotting factors.
  • Small-vessel thrombin deposition → Widespread thrombosis.

Purpura Fulminans

  • Severe DIC variant.
  • Diffuse small-vessel thrombosis.
  • Causes extensive tissue necrosis.

Clinical Features

  • Bleeding.
  • Thrombosis.

Causes

  • Most common: Sepsis.
  • Most important: APML
  • Others:
    • Vascular injury
    • Abruptio placentae
    • Snake bite
    • Pancreatitis
    • Adrenocarcinoma

Laboratory Parameters of DIC

Parameter
Finding
Specificity / Sensitivity
Platelets
Low
ㅤ
aPTT
High
ㅤ
PT
High
ㅤ
TT
Prolonged
Most specific test.
D-dimer
Elevated
Most specific test.
DD also indicates fulminant hepatic failure.
Fibrinogen
Decreased
ㅤ
FDP
Increased
Most sensitive test.
Peripheral Smear
Fragmented RBCs
ㅤ

Management

  • Treat underlying cause (primary step).
  • Replacement therapy:
    • Cryoprecipitate
    • FFP
  • Anticoagulation:
    • Standard Heparin (SARH)
    • Heparin
  • Avoid:
    • Single-factor replacement
      • Drotecogin alpha

Differential Clues (Comparison Mnemonics)

Suggestive of
Findings
Haemophilia
↑ PTT + Bleeding into muscles or joints
Von Willebrand Disease
↑ PTT + ↑ Bleeding Time + Mucosal bleeding
DIC
↑ PT + ↑ PTT + ↑ Bleeding Time + Bleeding (any site)
Idiopathic Thrombocytopenic Purpura (ITP)
↓ Platelets + Bleeding / Purpura + Hx of URTI