Disseminated intravascular coagulation

Question 1

What is disseminated intravascular coagulation?

Answer 1

1. Acquired syndrome characterised by activation of coagulation pathways, resulting in formation of intravascular thrombi and depletion of platelets and coagulation factors.
2. Disease states that trigger systemic activation of coagulation may lead to DIC

Question 2

In what different forms can DIC occur?

Answer 2

1. Acute overt form 
   - Endothelial damage leads to activation of tissue factor and thus explosive thrombin generation (sudden) and activation of platelets and clotting factors (to compensate) 
   - Compensatory mechanisms are overwhelmed = depletion of platelets and clotting factors -> bleeding 
   - Excess fibrin deposition (due to depletion of clotting factors) leads to Microangiopathic hemolytic anemia and organ ischaemia 
2. Chronic non-overt form (chronic) 
   - Endothelial damage leads to activation of tissue factor and thus thrombin generation  and activation of platelets and clotting factors (to compensate) (occurs slowly) 
   - Compensatory mechanism are thus NOT overwhelmed and excess coagulation occurs -> hypercoagulable state -> thromboembolism 

Question 3

What are the causes/ risk factors of DIC?

Answer 3

“STOP BMT”
- Sepsis
- Trauma
- Obstetric disorders
- Pancreatitis
- Burns
- Malignancy (Acute promyelocytic leukaemia (APL) is an uncommon subtype of AML that is associated with DIC)
- Transfusion reactions/transplant rejections

1. Acute DIC ⇒ rapid-onset underlying conditions such as trauma, sepsis and blood transfusions
2. Chronic DIC ⇒ less acute disorders such as malignancy

Question 4

What are the presenting symptoms of DIC?

Answer 4

• The patients will tend to be seriously ill unwell with symptoms/signs of underlying disease
• E.g. Fever, shock (hypotensive, tachycardia)
• Confusion 
• Dyspnoea 
• Evidence of bleeding 

Question 5

What signs of DIC can be found on physical examination?

Answer 5

1. Acute DIC 
   - Bleeding 
   - Petechiae, purpura, ecchymoses 
   - Epistaxis 
   - Mucosal bleeding 
   - Overt haemorrhage 
   - Signs of end organ damage 
   - Respiratory distress 
   - Oliguria due to renal failure 
2. Chronic DIC 
   - Signs of superficial/deep vein and arterial thrombosis or embolism 
   - Superficial venous thrombosis 

Question 6

What investigations are used to diagnose/ monitor DIC?

Answer 6

1. FBC → low platelets, low haemoglobin
2. Clotting → low fibrinogen, high D-dimer (fibrinogen degradation products), prolonged PT + APTT
3. Blood Film → schistocytes (fragmented part of RBC)

Question 7

How is DIC managed?

Answer 7

1. Treat Underlying Disease
2. Platelet + Coagulation Factors Transfusion
   - Fresh Frozen Plasma → contains clotting factors (AB = universal donor)
   - Cryoprecipitate → replaces fibrinogen
3. Anticoagulation → Heparin

Question 8

What blood features are associated with DIC?

Answer 8

DIC typical blood picture:
↓ platelets
↓ fibrinogen
↑ PT & APTT
↑ fibrinogen degradation products

Question 9

Summarise the epidemiology of DIC

Answer 9

• Seen in any severely ill patient