Blood clots

Blood cells travelling through the circulation system. Some blood cells are grouped together as a clot.

What is a blood clot?

A blood clot helps to repair injured blood vessels. However, when blood becomes semi-solid, the flow of blood within the circulation system can be obstructed. If not treated quickly, a blood clot can travel to an organ and stop blood flow and oxygen, resulting in a life-threatening condition. There are two types of blood clot:

  • Arterial clot: These form in an artery and result in symptoms that appear quickly.
  • Venous clot: These form more slowly than arterial clots but are still dangerous when left untreated.

A blood clot that prevents too much blood spilling from an injury is positive. However, if a blood clot forms in a healthy cell it can turn into a thrombus, another type of blood clot, which leads to thrombosis


In some cases, blood clots can dissolve on their own. In other cases, a blood clot can obstruct a vein, causing a life-threatening condition.

Blood clots can occur in:

Symptoms of blood clots

A blood clot can be asymptomatic (show no symptoms) or it can show symptoms which vary depending on where the obstructed blood vessel is.

If the blood clot affects a limb, most commonly a leg, there may be the following symptoms:

  • A cramping sensation
  • Swelling in the affected limb
  • Pain
  • Discolouration of the skin (such as a reddish or blue tint)

If the blood clot affects the heart, brain or lungs, the following symptoms can occur:

  • Difficulty speaking
  • Blurred vision
  • Sudden shortness of breath and difficulty breathing
  • Pressure or a stabbing pain in the chest

If you experience any symptoms, seek medical help immediately.

Medical tests to diagnose blood clots

If you’re suspected of having a blood clot, you may receive:

  • A physical examination
  • Venous ultrasound (ultrasound imaging of the veins in the body)
  • CT angiography (a type of x-ray) of the chest, head and neck, abdomen or pelvis

What are the causes?

Blood clots aren’t common in young healthy people but it’s still possible. Risk factors for blood clots are:

  • Ageing
  • Being overweight or obese
  • Smoking
  • Using some birth control methods - check your combined pill, vaginal ring or contraceptive patch instructions to check if the risk is increased
  • Pregnancy
  • Family history of blood clots
  • Sitting too long, particularly when the legs are crossed
  • An accident involving a traumatic injury
  • High cholesterol

Can blood clots be prevented?

Lifestyle choices can help to prevent blood clots:

  • Stay in a healthy weight range
  • Exercise
  • Stay hydrated
  • Wear flight socks if taking a long flight – these can be bought over-the-counter at pharmacies
  • Don't smoke

Treatments for blood clots

Your specialist will advise you on the best course of treatment based on:

  • If the blood clot is in a vein or artery
  • If it is near a specific organ
  • The risk of the blood clot causing serious complications – such as a stroke, heart attack or pulmonary embolism

Blood clots can dissolve on their own over time but if the examination findings suggest that the clot will result in a life-threatening condition, you may be prescribed anticoagulants (also referred to as blood thinners) to reduce the clot size and the likelihood or more clots forming.

Alternatively, surgery may be necessary to remove the clot. This is usually used when the diagnosis shows the clot is life-threatening or in emergency situations (where severe symptoms may have already developed).

Which type of specialist treats blood clots?

Many specialists can be involved in the treatment of blood clots, depending on where the blood clot is located. For example, a cardiologist for the heart, a pulmonologist for the lungs and a neurologist for the brain.

If you currently have or have had a blood clot, you may be referred to a haematologist (a blood specialist). A vascular surgeon performs the surgical removal of blood clots.

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