Venous disease
Deep Vein Thrombosis
A blood clot in the deep leg veins, diagnosed by ultrasound at consultation in Singapore. Prompt diagnosis prevents clots travelling to the lungs.
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 — one of the conditions I assess and treat in Singapore. 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.
Frequently asked questions
- What are the warning signs of a DVT?
- Swelling, pain and warmth in one leg are the typical signs, though a DVT can also be silent. A newly swollen, painful leg should be scanned within a day. Sudden breathlessness, chest pain or coughing blood alongside a swollen leg suggests a clot has travelled to the lungs — that is an emergency, and the right call is 995.
- How is a DVT diagnosed?
- Duplex ultrasound is the standard test and can be performed at the consultation itself, so the diagnosis is usually made in the same visit. Blood tests and further imaging are added where they are needed.
- Is blood-thinning medication the only treatment?
- Anticoagulation is the mainstay for most people: it prevents the clot extending while the body clears it, with compression to reduce swelling. In selected extensive clots, catheter-based thrombolysis or thrombectomy can remove the clot directly and help preserve the vein valves — which is the point of considering it early rather than late.
- What is post-thrombotic syndrome?
- The longer-term consequence of a DVT: the clot damages the vein valves, and over the following years the leg can develop chronic swelling, heaviness and skin changes. Prompt treatment and compression reduce the risk, and if it does develop it is assessed and managed in the same way as chronic venous insufficiency.
- Should the cause of a DVT be investigated?
- If a DVT was unprovoked — no recent surgery, immobility, long journey or other clear trigger — it warrants a thoughtful search for an underlying cause, because that shapes how long anticoagulation should continue and what else needs attention.