Haematology\ Venous Thromboembolism Flashcards
What are the three factors typically involved in thrombosis formation (and also make up Virchow triad)?
- Stasis of blood flow
- Vascular endothelial injury
- Hypercoagulable state
What is Homans sign?
Calf pain with passive ankle dorsiflexion associated with the presence of a deep venous thrombosis (DVT) (a frequently pimped but unreliable examination finding)
What physical examination findings suggest a DVT?
- Local edema (>3-cm diameter increase compared to the unaffected side)
- pain
- warmth
- a palpable cord (indicating a thrombosed vein)
- presence of newly developed varicose veins
What is the imaging study of choice to rule out DVT?
Compression ultrasonography
What is the role of D-dimers in the workup of suspected DVT?
D-dimer levels <500 ng/mL are helpful in excluding DVTs.
What are the risk factors for thrombsis?
- Inherited
- Protein C deficiency
- Factor V Leiden mutation
- Prothrombin gene mutation
- Antithrombin deficiency
- Protein S deficiency
- Acquired
- Malignancy
- Trauma
- Recent Surgery
- Pregnancy
- Drugs
- Immobilisation
- Heart failure
- Antiphospholipid syndrome
- Myeloproliferative disorders
- Hyperviscosity syndromes
- Hyperhomocysteinemia
- Nephrotic syndrome
- Obesity
- Past VTE
Do all DVT patients need a workup for an inherited thrombophilia?
No
What is the management of a DVT?
Unfractionated or low-molecular-weight heparin (LMWH) and warfarin
For how many days should treatment with heparin and warfarin overlap?
- At least 4-5 days
If heparin and warfarin have overlapped sufficiently and international normalized ratio (INR) has been therapeutic for two consecutive days, what should you do?
Discontinue heparin and continue warfarin alone.
How long should you continue oral anticoagulation with warfarin if the cause of the venous thromboembolism (VTE) is reversible?
3 months
How long should you continue oral anticoagulation with warfarin if its patient’s first idiopathic VTE?
6-12 months
How long should you continue oral anticoagulation with warfarin if the cause of the venous thromboembolism is irreversible?
indefinitely
What does INR stand for?
International normalized ratio
By whom and why was INR developed?
By the World Health Organization (WHO) in order to standardize prothrombin times
What INR is considered therapeutic for warfarin treatment of DVTs?
2-3
What should be done if anticoagulation is contraindicated (eg, active bleeding) or if anticoagulation has failed?
Place an inferior vena cava (IVC) filter
Is LMWH at least as effective as unfractionated heparin?
Yes
What are the advantages of using LMWH versus unfractionated heparin?
- Longer half-life allows for once or twice daily dosing
- doses are fixed
- monitoring of the activated partial thromboplastin time (aPTT) is not required
- thrombocytopenia is less likely
What percentage of symptomatic, untreated, proximal DVT patients will develop pulmonary embolism?
50%
What are the symptoms associated with pulmonary embolism (PE)?
- Dyspnea
- pleuritic pain
- cough
- hemoptysis
What are the signs associated with PE?
- Tachypnea
- rales
- diaphoresis
- tachycardia
- heart gallop
- a loud second heart sound
What chest x-ray (CXR) findings suggest a PE?
- Atelectasis
- Hampton hump
- Westermark sign
What is Hampton hump on CXR?
A triangular pleural-based density with an apex that points toward the hilum
