Symptoms — and why they're easily missed
DVT symptoms are notoriously non-specific. Up to 50% of DVTs — particularly calf DVTs — are completely asymptomatic and are only discovered incidentally during imaging. When symptoms do occur, they overlap with muscle injuries, cellulitis and other common conditions.
- Swelling in one leg (or, rarely, both) — particularly the calf or thigh
- Pain or tenderness in the leg — classically described as cramping or heaviness
- Warmth over the affected area
- Redness or discolouration of the skin
- A palpable cord in the calf (rare, but specific when present)
- Symptoms of PE if clot has migrated: sudden breathlessness, chest pain, rapid heart rate, coughing blood — these are medical emergencies
Risk factors
Diagnosis
The Wells Score is the standard pre-test clinical probability tool. It assigns points for risk factors and symptoms, stratifying patients into low, moderate or high probability before imaging.
D-dimer blood test is used in low-to-moderate probability cases — a negative D-dimer effectively rules out DVT in most patients. A positive D-dimer (which is non-specific and raised in many conditions) requires imaging to confirm or exclude a clot. Compression ultrasound of the leg veins is the primary imaging test — it is non-invasive, widely available and highly accurate for proximal DVT.
Treatment
Anticoagulation (blood thinning) is the mainstay of DVT treatment. Direct oral anticoagulants (DOACs) — rivaroxaban, apixaban — are now first-line and do not require routine monitoring. Treatment typically lasts 3–6 months for a provoked DVT and indefinitely for unprovoked or recurrent clots.
Below-knee compression stockings reduce the risk of post-thrombotic syndrome — persistent swelling, pain and skin changes in the affected leg. They are recommended for all patients with proximal DVT.