Disseminated intravascular coagulation (DIC)

Question 1

Define DIC

Answer 1

A disorder of the clotting cascade that can complicate a serious illness

Can occur in 2 forms:

• Acute overt form: bleeding and depletion of platelets and clotting factors
• Chronic non-overt form: thromboembolism is accompanied by generalised activation of the coagulation system

Question 2

Explain the Risk factors of DIC

Answer 2

• Infection: particularly gram ve- sepsis
• Obstetric complications:
  - missed miscarriage - foetus dies but the body doesn’t realise and placenta continues releasing hormones
  - severe pre-eclampsia
  - placental abruption (separation of placenta from uterus wall)
  - amniotic embolic
• Malignancy:
  - acute promyelotic leukaemia (acute DIC)
  - lung, breast and GI malignancy (chronic DIC)
• Severe trauma/surgery
• Others e.g. haemolytic transfusion reaction, burns, severe liver disease, aortic aneurysms, haemangiomas

Question 3

What is the Aetiology/pathophysiology of Acute DIC?

Answer 3

• Endothelial damage and the release of granulocytes/macrophage procoagulant substances (e.g. tissue factor) lead to activation of coagulation
• This leads to explosive thrombin generation, which depletes clotting factors and platelets, whilst also activating the fibrinolytic system
• This leads to bleeding in subcutaneous tissues, skin and mucous membranes
• Occlusion of blood vessels by fibrin in the microcirculation leads to microangiopathic haemolytic anaemia and ischaemic organ damage

Question 4

What is the Aetiology/pathophysiology of chronic DIC?

Answer 4

• Identical process to Acute DIC
• Happens at a slower rate with time for compensatory responses
• The compensatory responses diminish the likelihood of bleeding but give rise to hypercoagulable states and thrombosis can occur

Question 5

Summarise the epidemiology of DIC

Answer 5

Seen in any severely ill patient

Question 6

What are the presenting symptoms of DIC?

Answer 6

• Patient tends to be severely unwell with Symptoms of underlying disease
• Confusion
• Dyspnoea
• Evidence of bleeding

Question 7

What are the signs of DIC?

Answer 7

• Signs of underlying disease
• Fever
• Evidence of shock (hypotension, tachycardia)

Acute:

• Petichiae, purpura, ecchymoses
• Epistaxis
• Mucosal bleeding
• Overt haemorrhage
• Signs of end organ damage
• Respiratory distress
• Oliguria due to renal failure

Chronic:

• Signs of deep vein and arterial thrombosis or embolism
• Superficial venous thrombosis

Question 8

What are the appropriate investigations for DIC?

Answer 8

Bloods: FBC

• low platelets
• low Hb
• high APTT/PT
• low fibrinogen
• high fibrin degredation products
• high D-dimers

Peripheral blood smear