Evidence-based On-call

Deep vein thrombosis

Clinical features

Use the following clinical prediction rule to rank patients for their risk of having a DVT.

^a
For patients with symptoms in both legs, use the most symptomatic leg.

Clinical prediction rule to rank your patient's risk of a DVT

Ask about	Score
Active cancer (on-going treatment, diagnosed within the last 6 months or having palliative care)	+1
Paralysis, paresis, or plaster immobilisation of a leg	+1
Recently bedridden >3 days or major surgery within past 4 weeks	+1

Look for	Score
Localised tenderness over distribution of the deep veins ^a	+1
Entire leg swollen	+1
Calf circumference 10 cm below tibial tuberosity >3cm greater than other calf	+1
Pitting oedema only in the symptomatic leg ^a	+1
Collateral dilated (but not varicose) veins	+1
An alternative diagnosis as or more likely than DVT	-2

Match your patient's score to the risk.

Remember DVT cannot be safely diagnosed or excluded on history and physical examination alone. Imaging studies are necessary. ^a

In addition, ask about features that might affect your management:

recurrent venous thromboembolism ^a
a known clotting disorder ^b
a history of clotting disorders in first-degree relatives ^c
oral contraceptive pill ^bor HRT use ^a (especially with a known thrombophilia). ^b
current or recent pregnancy ^b (especially if known thrombophilia). ^c
- Ask which leg is affected: a DVT is less likely if the right leg is affected clinically. ^a

Don't bother asking how long she has been pregnant: the trimester does not help predict DVT. b

The following are not particularly helpful in diagnosing DVT:

asking about age, sex, symptom duration, recent trauma, a family history of venous thromboembolism, erythema, or recent hospital admission. ^a
looking for Homan's sign - it does not help diagnose or exclude DVT in hospital patients. ^a

Upper limb DVT

Check for common causes: ^c