DIC

Question 1

definition of DIC

Answer 1

A disorder of the clotting cascade that can complicate a serious illness. DIC may occur in two forms

1. Acute overt form where there is bleeding and depletion of platelets and clotting factors.
2. Chronic non-overt form where thromboembolism is accompanied by generalized activation of the coagulation system.

Question 2

aetiology of DIC

Answer 2

infection

• particularly gram -ve sepsis

obstetric complications

• missed miscarriage
• severe pre-eclampsia
• placental abruption
• amniotic emboli

malignancy

• acute promyelocytic leukaemia (acute DIC)
• lung, breast, GI - chronic DIC

severe trauma/injury

haemolytic transfusion reaction

burns

severe liver disease

aortic aneurysms

haemangiomas

Question 3

pathology of acute DIC

Answer 3

Activation of coagulation is a consequence of endothelial damage and increased release of granulocyte/macrophage procoagulant substances e.g. tissue factor (secondary to endotoxin, membrane lipopolysaccharides, cytokines such as IL-6 and TNF-a)

Explosive thrombin generation depletes clotting factors and platelets, AND activates the fibrinolytic system.

= bleeding in subcut tissues, skin and mucous membranes

occlusion of vessel by fibrin in microcirculation = microangiopathic haemolytic anaemia and ischaemic organ damage.

Question 4

pathology of chronic DIC

Answer 4

identical process to acute

slower rate with time for compensatory responses = reduced liklihood of bleeding but give rise to hypercoagulable state and thrombosis can occur

Question 5

epidemiology of DIC C

Answer 5

seen in any severely ill pt

Question 6

sx of DIC

Answer 6

patient is severely unwell

with symptoms of the underlying disease,

confusion, dyspnoea and evidence of bleeding.

Question 7

signs of DIC

Answer 7

signs of underlying aetiolgy, fever, evidence of shock (hypotension, tachycardia)

Question 8

signs of ACUTE DIC

Answer 8

petechiae

purpura

eccymoses

epistaxis

mucosal bleeding

bleeding anywhere - eg venepuncture site

overt haemorrhage

signs of end organ damage - local infarction/gangrene

resp distress

oliguria caused by renal failure

Question 9

signs of CHRONIC DIC

Answer 9

signs of deep venous thrombosis or arterial thombosis or embolism, superficial venous thrombosis - especially those w/o varicose veins

Question 10

Ix for DIC

Answer 10

blood

• FBC - low platelets, low Hb
• clotting - high APTT/PT/TT, low fibrinogen
• increased fibrin degredation products and d-dimers

peripheral blood film - red blood cell fragments (schistocytes)

other investigations according to aetiology