Deep Vein Thrombosis (DVT)

🔍 When to Suspect

Unilateral leg swelling, pain, tenderness, redness, or warmth, particularly in the calf, often with known risk factors for venous thromboembolism (VTE)

From the full topic in The Ocean Library: Deep Vein Thrombosis (DVT)

🧭 When to suspect

Suspect a deep vein thrombosis (DVT) in any adult with unilateral leg symptoms, classically in the calf:

• swelling

• pain

• tenderness

• warmth or redness

A DVT is a thrombus in a deep vein; the danger is that:

• the clot may extend proximally

• it may embolise to the lungs as a pulmonary embolism (PE), which can be fatal

The decisive distinction is proximal versus distal disease. A proximal DVT (at or above the popliteal trifurcation) is the clot that matters most – it is the source of virtually all clinically significant PE and the focus of NICE management.

In primary care, you need to:

• stratify probability with the 2-level DVT Wells score

• arrange the right test in the right order

• never miss a PE or a limb-threatening leg

In all non-pregnant adults with suspected DVT, calculate the 2-level DVT Wells score first – it decides whether the next step is an ultrasound or a D-dimer.

• The score is not validated in pregnancy.

• Pregnant or recently postpartum women follow a separate pathway.

2-level DVT Wells score – clinical feature	Points
Active cancer (treatment ongoing, within 6 months, or palliative)	1
Paralysis, paresis or recent plaster immobilisation of the lower limb	1
Recently bedridden ≥ 3 days, or major surgery within 12 weeks (general/regional anaesthesia)	1
Localised tenderness along the distribution of the deep venous system	1
Entire leg swollen	1
Calf swelling ≥ 3 cm larger than the asymptomatic side	1
Pitting oedema confined to the symptomatic leg	1
Collateral superficial veins (non-varicose)	1
Previously documented DVT	1
An alternative diagnosis is at least as likely as DVT	−2
DVT likely	≥ 2 points
DVT unlikely	≤ 1 point

Key risk factors to weight clinically:

• active cancer

• recent surgery, trauma or immobility (including long-haul travel and lower-limb plaster)

• oestrogen-containing contraception or HRT

• pregnancy/puerperium

• obesity

• increasing age

• a personal or family history of venous thromboembolism (VTE) or known thrombophilia

Source: NICE NG158 · NICE QS201

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