disseminated intravascular coagulation

Question 1

definition

Answer 1

Disseminated intravascular coagulation (DIC) is an acquired syndrome characterised by activation of coagulation pathways, resulting in formation of intravascular thrombi and depletion of platelets and coagulation factors. Thrombi may lead to vascular obstruction/ischaemia and multi-organ failure. Spontaneous bleeding may occur. Generalised bleeding, evidenced by at least 3 unrelated sites, is highly suggestive of DIC.

DIC can be triggered by major trauma, organ destruction, sepsis or severe infection, severe obstetric disorders, some malignancies, major vascular disorders, and severe toxic or immunological reactions.

Question 2

chronic and acute DIC

Answer 2

Acute DIC is characterised by rapid-onset generalised bleeding and microcirculatory/macrocirculatory thrombosis, resulting in hypoperfusion, infarction, and end-organ damage.
Chronic DIC is characterised by subacute bleeding and diffuse thrombosis.

Question 3

causes

Answer 3

Disease states that trigger systemic activation of coagulation may lead to DIC. Causes include:

Sepsis/severe infection, major trauma or burns
Some malignancies (acute myelocytic leukemia or metastatic mucin-secreting adenocarcinoma)
Obstetric disorders (amniotic fluid embolism, eclampsia, abruptio placentae, retained dead fetus syndrome)
Severe organ destruction or failure (severe pancreatitis, acute hepatic failure)
Vascular disorders (Kasabach-Merritt syndrome or giant haemangiomas, large aortic aneurysms)
Severe toxic or immunological reactions (blood transfusion reaction or haemolytic reactions, organ transplant rejection, snake bite).
DIC induced by these causes may be acute or chronic.

Acute DIC is more common with rapid-onset underlying conditions such as major trauma, sepsis/severe infection, and massive blood transfusion.

Chronic DIC is more common with less acute disorders such as malignancies, paroxysmal nocturnal haemoglobinuria, and Raynaud’s disease. Localised DIC (characterised by bleeding or thrombosis limited to a specific anatomical location) is associated with an underlying disorder such as aortic aneurysm, giant haemangioma, and hyperacute renal allograft rejection

Question 4

signs and symptoms

Answer 4

due to circulatory collapse:
- oliguria (very little urine), hypotension, tachycardia

due to microvascular/macrovascular thrombosis:

• purpura fulminans, gangrene, acral cyanosis
• delirium or coma

generalised bleeding with 3 or more unrelaed sites affected
- petechiae, ecchymosis, oozing, haematuria

Question 5

risk factors

Answer 5

• major trauma/burn or sepsis/infection
• severe obstetric disorders or complications
• solid tumours or haematological malignancies
• severe toxic or immunological reactions

Question 6

investigations

Answer 6

1st investigations:

• platelets and fibrinogen => decreased because used up to make tiny clots, and fibrinogen used to make fibrin
• Prothrombin time (PT)/activated partial thromboplastin time (APTT) => increased
• d-dimer/fibrin degradation products => elevated

others:

• thrombin time => prolonged
• protamine => elevated
• factor 5, 8. 10, 13 => decreased