Disseminated Intravascular Coagulation (DIC) Flashcards
1.
Describe what is meant by Disseminated Intravascular Coagulation (DIC) [1]
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.
Describe the pathophysiology of DIC [+]
DIC does not arise by itself but instead develops on a background of some other severe pathology.
Triggers can include:
- Infectious causes (e.g. sepsis)
- non-infectious causes (e.g. malignancy or severe burns)
The triggers lead to a release of pro-inflammatory cytokines in a so-called systemic inflammatory response
These triggers lead to intravascular activation of the coagulation cascade
At the same time, widespread activation of coagulation leads to a reduction in the concentration of circulating coagulation factors.
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
Thus, in severe DIC there is paradoxically simultaneous thrombosis and spontaneous bleeding.
What does the term ‘consumptive coagulopathy’ refer to? [1]
When clotting factors are being used up (consumed) by intravascular thrombosis.
Describe 7 causes of DIC [7]
Shock
Sepsis/severe infection:
- these lead to the massive release of pro-inflammatory cytokines in a systemic inflammatory response. These cytokines can activate the coagulation system.
Major trauma or burns
Malignancies:
- including both solid organ and haematological malignancies. Acute promyelocytic leukaemia (APML) is strongly associated with DIC.
Obstetric emergencies:
- including eclampsia, HELLP (haemolysis, elevated liver enzymes and low platelets) syndrome, placental abruption, intrauterine death and amniotic fluid embolism.
Severe immune-mediated reactions:
- such as acute haemolytic transfusion reactions due to mismatched ABO antigens, organ transplant rejection and bites from certain venomous snakes.
Severe organ dysfunction:
- including acute hepatic failure and severe acute pancreatitis.
Describe the clinical features of DIC
The features of DIC can vary from a mild chronic form with little overt features to an acute and catastrophic event resulting in severe, spontaneous haemorrhage and multi-organ failure
- Bleeding from unusual sites: ears, nose, gastrointestinal tract, genitourinary tract, respiratory tract or sites of venepuncture or cannulation. Bleeding from three unrelated sites is highly suggestive of DIC.
- Widespread or unexpected bruising without a history of trauma
- Petechiae or purpura
- Livedo reticularis: a mottled lace-like patterning of the skin
- Purpura fulminans: widespread skin necrosis
- Localised infarction and gangrene for instance of the digits
Describe the typical blood picture seen in DIC [4]
Low platelets
Prolonged APTT, prothrombin and bleeding time
Fibrin degradation products are often raised
Schistocytes due to microangiopathic haemolytic anaemi
What is meant by Purpura Simplex? [1]
What are platelets, PT and APPT like in this condition? [3]
Purpura simplex is increased bruising that is due to fragile blood vessels.
Platelets:
- Normal
PT:
- Normal
APTT:
- Normal
What are platelets, PT and APPT & fibronogen like in DIC? [3]
Platelets:
- Thrombocytopenia
PT:
- Prolonged
APTT:
- Prolonged
Fibronogen:
- Decreased
What investigatons would you expect to see in alcohol abuse/liver cirrhosis? [3]
- Abnormal LFTs
- Prolonged PT and APTT
- Low albumin
What effect does heparin have on APTT? [1]
Increases
What effect does wafarin have on INR? [1]
Increases
What investigations would you expect to see in haemophilia? [2]
Prolonged APTT
Reduced FVIII or factor IX levels
