Venous disease
Deep Vein Thrombosis
A blood clot in the deep veins of the leg. Prompt diagnosis prevents clots travelling to the lungs and protects the leg long-term.
Last reviewed 1 Jul 2026
Reviewed by Dr Tay Jia Sheng · Vascular, Endovascular & General Surgeon
What is deep vein thrombosis?
Deep vein thrombosis (DVT) is a blood clot forming in the deep veins, usually of the leg. It typically causes swelling, pain and warmth in one leg — though it can be silent. The immediate danger is pulmonary embolism, where part of the clot travels to the lungs. The longer-term risk is post-thrombotic syndrome: chronic swelling, heaviness and skin changes in the affected leg.
How it is diagnosed
Duplex ultrasound is the standard test and can be performed at the time of consultation. Blood tests and further imaging are added where needed.
Treatment
- Anticoagulation — blood-thinning medication is the mainstay, preventing clot extension while the body clears it
- Compression therapy — reduces swelling and the risk of post-thrombotic syndrome
- Clot removal procedures — in selected extensive cases, catheter-based thrombolysis or thrombectomy can clear the clot and preserve the vein valves
- Investigating the cause — unprovoked DVT warrants a thoughtful search for underlying causes
When to seek help urgently
Sudden breathlessness, chest pain or coughing blood alongside a swollen leg is an emergency — call 995. A newly swollen, painful leg on its own should be scanned within a day.