Disseminated intravascular coagulation

• Disseminated intravascular coagulation (DIC) is a serious disorder occurring in response to an illness or disease process which results in dysregulated blood clotting.
• In health, there is usually a balance between the clotting and fibrinolytic systems. However, in DIC inappropriate activation of one or both systems leads to a paradoxical tendency to both bleeding and thrombosis simultaneously.
• Triggers for DIC are varied but in general, may include infectious causes (e.g. sepsis) and non-infectious causes (e.g. malignancy or severe burns).
• Some trigger conditions such as sepsis and trauma lead to a release of pro-inflammatory cytokines in a so-called systemic inflammatory response. In other conditions, the expression of certain pro-coagulant factors, such as tissue factor, is upregulated.
• Pro-inflammatory cytokines and tissue factor lead to intravascular activation of the coagulation cascade throughout the body.
• Microvascular thrombosis results due to the formation of fibrin webs and the activation and aggregation of platelets within the small blood vessels. These small thrombi can lead to multi-organ failure due to tissue ischaemia.
• At the same time, widespread activation of coagulation leads to a reduction in the concentration of circulating coagulation factors. This is referred to as a consumptive coagulopathy since clotting factors are being used up (consumed) by intravascular thrombosis.
• As the concentration of available clotting factors falls, the risk of bleeding increases. Platelets are also being used up due to activation and aggregation within the circulation, which leads to thrombocytopenia, further increasing the risk of bleeding.
• DIC pathway:

  A) multi-organ failure

  B) thrombosis

  C) bleeding

  
• DIC is also called a consumption coagulopathy, because all this clotting consumes platelets and clotting factors.
• The formation of the platelet plug is called primary hemostasis.
• As soon as a clot is formed, the body is also initiating pathways to break down the clot so that it doesn’t get bigger than it needs to be and dissolves when it’s not needed anymore—a process called fibrinolysis.
• In serious medical conditions, like for example sepsis, malignancy, serious trauma, obstetric complications, or intravascular hemolysis like you might see with blood type incompatibility, there can be a release of a procoagulant that tips the scales in favor of clot formation.
• Haemostasis goes out of control.
• AKA consumption coagulopathy.
• Kidneys, liver, lungs and brain are most at risk of ischaemia and necrosis in DIC.
• Lab findings in DIC:

  Decreased platelets

  Decreased fibrinogen

  Prolonged prothrombin time (PT)

  Prolonged Partial thromboplastin time (PTT)

  Elevated D-Dimer - fibrin degradation product
• Prolonged PT and PTT reflects low circulating coagulation factors.
• Treatment of DIC:

  Focus on underlying cause

  Support organs - ventilator, haemodynamic support, transfusions
• DIC happens when the balance between forming clots and breaking down clots in tipped to forming clots leading to widespread clotting and ischaemia which depletes clotting factors eventually leading to bleeding.