Deep Vein Thrombosis

Probability assessment (Wells score)

Deep vein thrombosis

Clinical feature Score
0 or less = low probability; 1-2 = moderate probability; 3 or more = high probability
Active cancer (ongoing or < six months) 1
Paralysis, paresis, or recent plaster immobilisation 1
Recently bedridden >3 days, or major surgery <4 weeks 1
Localised tenderness along deep venous system 1
Entire leg swollen 1
Calf swelling >3 cm vs other leg (10 cm below tibial tuberosity) 1
Pitting oedema (greater in the symptomatic leg) 1
Collateral superficial veins (non-varicose) 1
Alternative diagnoses as likely, e.g. Baker's cyst, superficial thrombophlebitis, cellulitis) -2

Pulmonary embolism

Clinical feature Score
Either:<=4 - unlikely; >4 - likely
or <2 - low; 2-6 = moderate; >6 - high
Clinical signs and symptoms of DVT 3
PE is top or joint-top diagnosis 3
Heart rate>100 1.5
Immbolization >3 days, or surgery in last 4 weeks 1.5
Previous objectively diagnosed DVT or PE 1.5
Haemoptysis 1
Malignancy with treatment within 6 months, or palliative 1

Oral contraceptive pill - up to 6x risk
HRT - approx double risk. Includes tibolone, raloxifene
Previous VTE
Age (40 years or older)
Genetic coagulopathies - factor V Lieden, protein C & S deficiencies, antithrombin deficiency, prothrombin gene mutation. Usually require an additional risk factor to cause DVT.
Acquired coagulopathies - lupus anticoagulant and antiphospholipid antibodies, myeloproliferative disorders e.g. polycythaemia rubra vera
Pelvic mass or lymph nodes


Remember: the superficial femoral vein is a deep vein.


See section on warfarin and heparin for more info.