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Disseminated Intravascular Coagulation

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Overview

Disseminated intravascular coagulation (DIC) is a set of signs and symptoms characterised by the activation of coagulation pathways and intravascular blood clots throughout the body (disseminated intravascular coagulation). This leads to the depletion of platelets and coagulation factors, resulting in organ dysfunction.

DIC is generally triggered by acute, severe stresses on the body such as sepsis. The development of DIC increases mortality from the underlying condition.

Pathogenesis

Tissue factor (TF) is present in many cell types but is not generally exposed to the circulation unless damage occurs. Inflammation can lead to the release of TF which binds with coagulation factors triggering the extrinsic clotting pathway, leading to disseminated coagulation.

Causes

  • Sepsis
  • Major trauma/burns
  • Malignancy
  • Severe pancreatitis
  • Severe organ dysfunction (e.g. acute liver failure/pancreatitis)
  • Pregnancy complications (e.g. eclampsia/amniotic fluid embolism)
  • Blood transfusion reactions
  • Organ rejection

Example History

A 75-year-old man is admitted to the hospital for sepsis secondary to community-acquired pneumonia. His blood pressure is 95/50 mmHg, his heart rate is 140 bpm, and his temperature is 38.4°C. On examination, there is bruising over his arms and bleeding from his cannula.

Investigations:

Platelets:51 x 109/L(150 – 450 x 109/L)
Prothrombin time (PT):25 s(10 – 12 s)
Activated partial thromboplastin time (APTT):48 s(22 – 41 s)
Fibrinogen:0.8 g/L(1.5 – 4.0 g/dL)
D-dimer:1130 µg/L(0 – 500 µg/L)

Presentation

Patients are generally haemodynamically unstable with bruising and petechiae. Features include:

  • Signs of an underlying cause (e.g. sepsis)
  • Features due to thrombocytopenia:
    • Bleeding
    • Bruising
  • Haemodynamic instability
    • Tachycardia
    • Hypotension

Differential Diagnoses

Other microangiopathic haemolytic anaemias (e.g. TTP/HUS):

  • In TTP, patients usually have fevers and neurological symptoms
  • HUS is more common in children and associated with AKI and bloody diarrhoea
  • FBC shows anaemia alongside thrombocytopenia
  • Lactate dehydrogenase/bilirubin is elevated and haptoglobins are low due to haemolysis
  • APTT, PT, and fibrinogen degradation products tend to be normal

Heparin-induced thrombocytopenia (HIT)

  • There is a history of heparin use
  • No underlying trigger for DIC is seen
  • Blood tests are positive for HIT antibodies and HIT functional assays are positive

Acute severe liver failure

  • Liver function tests may be deranged
  • Fibrin degradation products tend to be normal
  • However, this can cause DIC

Investigations

Overview

Important investigations include:

  • Full blood count (FBC):
    • Shows thrombocytopenia
  • Blood film:
    • May show schistocytes
      • Clots form in blood vessels which can shred red blood cells (microangiopathic haemolytic anaemia)
      • This is not specific to DIC as they can occur in other microangiopathic haemolytic anaemias such as haemolytic uraemic syndrome
  • Coagulation testing:
    • Increased prothrombin time (PT):
      • Measures extrinsic and common pathways
    • Increased activated partial thromboplastin time (APTT):
      • Measures intrinsic and common pathways
    • Increased D-dimer/fibrinogen degradation products
      • These rise after any thrombotic event when fibrin and fibrinogen break down
      • D-dimer is the most  notable fibrin degradation product
      • Fibrin is responsible for clot retraction
    • Decreased fibrinogen – but may be normal/elevated
      • Fibrinogen is converted into fibrin to make clots and is broken down into fibrin degradation products, however, it is a positive acute-phase reactant, which may give a normal/high result 

Diagnosis

Diagnosis is based on clinical features and investigations

Management

Overview

Management is supportive alongside treating the underlying cause:

  • Platelet transfusions may be given
    • Only if patients are bleeding or at a high risk of bleeding
  • Correction of prolonged PT and APTT with fresh frozen plasma (FFP)
    • Only if patients are bleeding or at a high risk of bleeding
  • Other options include:
    • Prothrombin complex concentrate
    • Fibrinogen concentration
    • Cryoprecipitate

Complications

  • Organ failure
    • Due to thrombi in blood vessels causing ischaemia and failure
    • Causes relating to the underlying cause can also contribute to this (e.g. hypotension in septic shock)
  • Severe haemorrhage
  • Cardiac tamponade
  • Intracranial bleed
  • Gangrene

Prognosis

  • DIC can rapidly lead to organ failure and can be fatal if not identified and treated early.
  • The development of DIC increases the mortality associated with the underlying condition.

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