Deep Vein Thrombosis Flashcards
What is the definition of a deep vein thrombosis?
A clot in a vein - commonly in the pelvis or leg
- other locations indicate a more sinister underlying cause
What are the risk factors for a deep vein thrombosis?
Increased age Pregnancy/synthetic oestrogen Trauma Surgery (especially pelvic and orthopaedic) Past DVT Obesity Cancer Immobility Thrombophilia
What is Vichow’s triad of risk factors?
Stasis
Hypercoagulability
Vessel wall injury
What are the clinical features of a DVT?
Calf warmth, swelling, tenderness and erythema
Pitting oedema
Fever
What are the components of the Wells score?
Active cancer
Paralysis, paresis or recent plaster immobilisation of the leg
Recently bedridden for >3 days
Major surgery within 12 weeks
Local tenderness along the deep vein system
Entire leg swollen
Calf swelling >3cm than non-symptomatic leg
Pitting oedema
Collateral (non-varicose) superficial veins
Previously documented DVT
Alternative diagnosis as likely as DVT ( - 2 points)
How is a DVT diagnosed?
Wells score 1 or less
- perform d-dimer (negative excludes DVT, positive requires USS)
- USS (positive diagnoses DVT)
Wells score 2 or more
- d-dimer and USS (both negative excludes DVT, USS only positive diagnoses DVT, d-dimer only positive requires USS repeat in one week)
When would a thrombophilia test be performed?
Before anti-coagulant therapy
Recurrent DVTs
DVT in an unusual location
What are some other causes of a raised d-dimer?
Recent surgery Infection Pregnancy Malignancy D-dimer is a breakdown product of fibrin and is released in many processes
What is the treatment of a DVT?
Low molecular weight heparin (enoxaparin) or fondaparinux started immediately and continued for 5 days
- unfractioned heparin is used in renal failure or if there is an increased risk of bleeding
Warfarin started at the same time as LMWH (pro-thrombotic for first 48 hours)
Consider DOACs
IVC filters to minimise PE risk if anticoagulation fails
Graded compression stockings (post-thrombotic change protection)
What is post-thrombotic change?
Pain, swelling and skin changes over the affected area
How long does the treatment for a DVT last?
3 months - after 1st DVT
6 months - 1st DVT in post-op or cancer patients
Permanently - in recurrent DVTs or if the patient has a genetic clotting disorder
What methods of prevention are surgical patients provided with?
Stop OCP 4 weeks pre-op
Mobilise quickly post-op
LMWH for high risk patients
Graduated compression stockings and intermittent pneumatic compression devices
Fondaparinux instead of LMWH in major orthopaedic surgery to reduce bleeding risk
