Bleeding and thrombotic disorders Flashcards
What is disseminated intravascular coagulation?
- An acquired, consumptive process
- The coagulation cascade is activated and micro thrombi are laid down (intravascular deposition of fibrin) leading to thrombosis of small and midsize vessels and organ failure
- Exhaustion of the coagulation cascade resulting in bleeding due to decreased platelets and coagulation factors
What are the causes of disseminated intravascular coagulation?
- Sepsis
- malignancy
- massive haemorrhage
- Severe trauma
- Pregnancy complications e.g. pre-eclampsia, placental abruption, amniotic fluid embolism
What are the investigations that should be carried out in DIC?
- Coagulation PT, aPTT and fibrinogen
- D-dimers
- FBC and film
What is the treatment of DIC?
- Treat underlying cause!!
- Fresh frozen plasma +/- platelets if bleeding or high risk for bleeding
Why is fibrinogen low in DIC?
Because it is being converted into fibrin
Why are d dimers increased in DIC?
Because fibrin is being broken down to d dimers
What can you do if a patient who is on warfarin has a high INR?
- Stop warfarin or reduce the dose
- Give vitamin K (oral or IV)
- Give coagulation factors (II, VII, IX and X) - prothrombin complex concentrates e.g. beriplex or octaplex
Describe the pathogenesis of coagulopathy in liver disease
- Poor coagulation factor synthesis in the liver
- Vitamin K deficient (poor diet ± obstructive component to jaundice)
- Poor clearance of activated coagulation factors
- DIC
- Hypersplenism leading to low white blood cells and platelets
- Reduced thrombopoietin synthesis leading to low platelets
If a patient has prolonged APTT, what test should you do next?
- Mix the patient plasma with normal plasma (1:1 ratio)
- If there is a full correction of APTT, then there is a factor deficiency
- If there is a partial correction of APTT, then there is a inhibitor
What is lupus anticoagulant?
- Phospholipid dependent antibody
- It interferes with phospholipid depended tests such as APTT resulting in a prolonged APTT
- If persistent then may be associated with a prothrombotic state
What is antiphospholipid syndrome?
Persisting lupus anticoagulant and thrombosis (or recurrent foetal loss)
Explain how you can test for lupus anticoagulant
- APTT is often prolonged
- APTT 50:50 dilution only partially corrects
- DRVVT (dilute Russel viper venom test) ratio is prolonged but corrects with excess phospholipid
What is acquired thrombophilia?
•Acquired antiphospholipid syndrome •Presence of antiphospholipid antibodies - lupus anticoagulant - anti cardiolipin antibodies - beta-2 glycoprotein 1 antibodies
What is the mechanism of acquired thrombophilia?
Disruption of annexing V shield exposing excess phospholipid
What is the clinical scenario of acquired thrombophilia?
- Venous/arterial thrombosis with a high risk of thrombosis recurrence
- Recurrent miscarriage