World Thrombosis Day 2026: DVT, PE and Blood Clot Warning Signs

With Dr Andrew Choong, vascular and endovascular surgeon in Singapore

Published 13 October 2026 · 1 min 36 sec · Watch on YouTube

About this video

Blood clotting is normal and essential: it is what stops bleeding after a cut or an injury. In this video for World Thrombosis Day, 13 October, Dr Andrew Choong explains what happens when a clot forms where it should not, inside a blood vessel. In an artery, a clot can block blood flow to the brain, the heart or the leg, causing a stroke, a heart attack or limb-threatening ischaemia.

The clot most people need to understand is a venous clot: a deep vein thrombosis (DVT) in the deep veins of the leg. The leg may become swollen, painful, red, warm or tight, often on one side only. The danger is that part of the clot can break off and travel to the lungs as a pulmonary embolism. One-sided leg swelling should not be ignored, especially after surgery, a long flight, prolonged immobility, cancer, pregnancy or a previous clot.

Sudden breathlessness, chest pain, coughing blood or collapse may indicate a pulmonary embolism. Seek emergency care immediately; call 995 in Singapore for life-threatening symptoms. A new swollen, painful leg needs medical assessment the same day.

Related patient information

• Read the full article: World Thrombosis Day 2026 and the warning signs of a blood clot
• DVT symptoms and diagnosis
• Pulmonary embolism
• DVT treatment: medicines and selected procedures
• Vascular ultrasound assessment
• World Thrombosis Day 2026: preventing blood clots in hospital

More blood clot videos

• DVT and pulmonary embolism: the warning signs
• What is a deep vein thrombosis?
• What is a pulmonary embolism?
• Why blood clots form
• The DVT treatment window
• World Heart Day: heart attack, brain attack, leg attack