Blood clots

Thrombosis is the formation of a blood clot in a blood vessel. A deep venous thrombosis, or DVT, is when a blood clot forms in a deep vein, most often in the leg. These can travel in the circulation and lodge in the blood vessels of the lungs. This is known as a pulmonary embolism, or PE.

You may have a higher risk of developing blood clots if you have cancer, but blood clots are also a potential side-effect of some cancer drugs. You may need to take a medication to help prevent a blood clot, particularly if you are admitted to hospital.

Deep venous thrombosis (DVT)

A DVT is a blood clot that forms in a deep vein, usually in your leg or groin, but it can also occur in the arm or neck, particularly if you have an indwelling intravenous line, sometimes used for giving chemotherapy

Symptoms of a DVT in your leg or arm include:

• Redness or discolouration
• Swelling in one limb
• Pain or tenderness

You may have no symptoms at all.

Pulmonary embolism (PE)

A pulmonary embolism is when a DVT or part of it breaks off, travels in the blood and becomes lodged in a blood vessel in your lungs.

Symptoms of a PE include:

• Chest pain (which may be worse on deep breath)
• Shortness of breath and/or rapid breathing
• Coughing up blood
• Feeling light-headed or dizzy

What should I do if I have symptoms?

Contact your doctor or specialist nurse immediately if you feel you have these symptoms. Most blood clots can be successfully treated if detected early. They can be serious if left untreated.

How are they treated?

If you have a blood clot you will usually be given medicine called an anticoagulant to thin your blood.

How can you help prevent blood clots?

• You may need to take medicine (anticoagulant) to help prevent blood clots forming, particularly if you are admitted to hospital. Discuss this with your medical team.
• Keep as active as possible – move your legs and feet often when you’re in bed, take regular walks and try not to sit for long periods.
• Drink lots of water – dehydration can contribute to blood clots. Avoid alcohol as it can make you dehydrated.
• Don’t smoke (or give up smoking*).
• Try to lose weight if you are overweight.
• Wear compression stockings (to improve your blood flow) if you have had surgery, until you are able to move around freely.
• Wear compression stockings if you are going on long journeys, such as a long-haul flight – your pharmacist or doctor can advise you about this.

*Reviewed by Dr Karl Ewins, consultant haematologist (July 2021)