DVT Flashcards
What % of surgical patients do DVTs occur in?
25-50%
What is Virchow’s Triad?
Blood contents
Blood flow
Vessel wall
What are the ‘blood contents’ risk factors for DVT post-operatively?
Surgery causes an increase in platelets and fibrinogen
Dehydration
Malignancy
Increasing age
What are the ‘blood flow’ risk factors for DVT post-operatively?
Surgery
Immobility
Obesity
What are the ‘vessel wall’ risk factors for DVT post-operatively?
Damage to veins, especially pelvic veins
Previous VTE
When does post-operative DVT have its peak incidence?
5-10 days post-op
What % of below knee DVTs are asymptomatic?
65%
What are the symptoms of DVT?
Calf warmth, tenderness, erythema, and swelling
Mild pyrexia
Pitting oedema
What are the differential diagnoses for DVT?
Cellulitis
Ruptured Baker’s cyst
How are DVTs investigated post-operatively?
Compression US
Thrombophilia screen?
What is found on compression US in DVT?
Clot will be incompressible
When is a thrombophilia screen required in post-operative DVT?
If no precipitating factors, recurrent DVT, or family Hx
How is decided how to investigate a suspected post-op DVT?
Assess probability using Wells’ Score
How is suspected post-op DVT investigated if it was a low-probability on Wells’ score?
Perform D-Dimers - if negative excludes DVT, if positive do compression US
How is suspected post-op DVT investigated if med/high probability on Wells’ score?
Compression US
How is post-op DVT managed?
Anti-coagulation
Graduated compression stocking
How is a patient with DVT anti-coagulated?
Therapeutic LMWH
Start warfarin using Tait model
What is given in therapeutic LMWH?
Enoxaparin 1.5mg/kg/24hour SC
What is the Tait model of warfarin?
Give 5mg OD for first 4d
How long should LMWH be given in DVT?
Until INR 2.5
How long should warfarin be given in a patient with a below knee DVT?
6-12 weeks
How long should warfarin be given in a patient with an above knee DVT?
3-6 months
How long warfarin be given in a patient with an ongoing cause for DVT?
Indefinite
When should graduated compression stockings be considered in post-op DVT?
For prevention of post-phlebitic syndrome
How is DVT prevented pre-operatively?
Pre-op VTE risk assessment
TED stockings
Aggressive optimisation, especially hydration
Stop OCP 4 weeks pre-op
How is DVT prevented intra-operatively?
Minimise length of surgery
Use minimal access surgery where possible
Intermittent pneumatic compression boots
How is DVT prevented post-operatively?
LMWH Early mobilisation Good analgesia Physio Adequate hydration
