Blood vessel with clotted blood cells

What is a blood clot?

Blood clotting is a normal process of the body to stop excessive bleeding when a blood vessel is injured.

Image from video showing blood cells in a blood vessel. Click to play video.
Click here to watch a short video on the formation
of blood clots

When can blood clotting be a problem?

Sometimes blood clots form abnormally within a blood vessel. In some cases the clot becomes large enough to block the blood flow.

The medical term for development of an abnormal blood clot is thrombosis.

Sometimes all or part of a blood clot breaks off and travels to other parts of the body. This is called an embolism.

Read further to understand more about thrombosis and embolism, and who is at risk.

Patient's hands grasping their lower leg

Deep Vein Thrombosis

What is a deep vein thrombosis?

  • A deep vein thrombosis or DVT is a blood clot that forms in a deep vein
  • DVT mostly occurs in the deep veins of the legs, but can also occur in other parts of the body such as the veins of the arms or the abdomen

What are the symptoms of DVT?

Not everyone with DVT will experience symptoms. When symptoms are present they may include:

  • Swelling of the leg or arm (sometimes it occurs suddenly)
  • Pain or tenderness in the leg that may only be felt when standing or walking
  • Feeling of increased warmth in the area of the leg or arm that is swollen or that hurts
  • Redness or discolouration of the skin
Patient’s torso with hand on chest

Pulmonary Embolism

What is a pulmonary embolism?

  • A pulmonary embolism or PE is a blood clot in a pulmonary (lung) vessel
  • A PE occurs when a blood clot breaks off, travels through the blood stream and lodges in the lung, blocking the blood flow

What are the symptoms of PE?

Symptoms of PE can include:

  • Sudden sharp chest pain
  • Shortness of breath
  • Chest pain that gets worse with deep breathing or coughing
  • Coughing up blood or pink, foamy mucus
  • Rapid heart rate
  • Excessive sweating

Together, DVT and PE are known as venous thromboembolism or VTE.