DIC

Question 1

define DIC?

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.

Question 2

outline the causes/risk factors of DIC?

Answer 2

Sepsis/severe infection, major trauma or burns- INFECTION IS PARTICULARLY GRAM NEGATIVE

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).

Question 3

state obstetric complications that can cause DIC?

Answer 3

• missed miscarriage ( when foetus dies but the body doenst realise it and the body continues to release hormones)
• severe pre-eclampsia
• placental abrutpion ( separation of placenta from wall of uterus during pregnancy)
• amniotic emboli

Question 4

what vascular disorders can cause DIC?

Answer 4

Kasabach-Merritt syndrome

Giant haemangioma

Large AAA

Question 5

Describe the pathophysiology of acute DIC?

Answer 5

Endothelial damage and the release of granulocyte/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 the 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 6

Which maligancies cause DIC?

Answer 6

Acute promyelocytic leukaemia - ACUTE DIC

Lung, breast and GI malignancy - CHRONIC DIC

Question 7

Describe the pathophysiology of chronic DIC?

Answer 7

IDENTICAL process to acute DI

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 8

Describe the epidemiology of DIC?

Answer 8

Seen in any severely ill patient

Question 9

What are the presenting symptoms of DIC?

Answer 9

The patients will tend to be severely unwell with symptoms of the underlying disease

Confusion

Dyspnoea

Evidence of bleeding at atleast 3 unrelated sites= highly suggestive of DIC

Question 10

what are the signs of DIC on physical examination?

Answer 10

Bleeding features

• Petechiae
• Ecchymoses
• Haematuria

Haemolytic features

• Jaundice
• Conjunctival pallor

Question 11

what are the appropriate investigations for DIC and what is seen?

Answer 11

FBC

• Low platelets
• Low Hb
• High PT (APTT is high sometimes but not always)
• Low fibrinogen
• High fibrin degradation products
• High D-dimers(FDP)
• FV, VII, X, XIII – helps in deciding replacement therapy

Peripheral Blood Film

• Schistocytes

Question 12

what is seen on the peripheral blood film in DIC?

Answer 12

SHISTOCYTES

Question 13

what are the signs of chronic DIC?

Answer 13

Signs of deep vein and arterial thrombosis or embolism

Superficial venous thrombosis