Blood clots and deep vein thrombosis (DVT)

If you have left the emergency department (A&E) or urgent care centre with a lower limb plaster cast, splint or walker boot, it's important to know about blood clots and deep vein thrombosis (DVT).

DVT is a blood clot that forms in one of the deep blood vessels. It usually happens in your leg or pelvis (the area between the hip bones, in the lower part of the tummy). 

A blood clot is not life-threatening by itself. Sometimes, however, it can move out of position and travel to your lungs. This is called a pulmonary embolism (PE) and can be very serious.

Ask for an urgent GP appointment or call 111 if:

  • you have new pain in your leg
  • you have new swelling in your leg
  • you have warm or discoloured skin on your leg

Call 999 or go to A&E if:

You have any symptoms of DVT and:

  • you are breathless
  • you have pain in your chest, back or ribs that is worse when you breathe in
  • you are coughing up blood

These can be signs that the blood clot has travelled to your lungs. This is called a pulmonary embolism. It can be life-threatening and needs treatment straight away.

Who is at risk of DVT

You may be at risk of getting DVT if your mobility (movement) is reduced for a while. Some people are more likely to get DVT than others.

DVT is more likely to happen if you:

  • are over 60
  • smoke
  • are dehydrated
  • take the oral contraceptive pill or hormone replacement therapy (HRT)
  • are overweight or obese
  • have cancer or cancer treatment
  • have underlying ‘sticky blood’ (a condition that makes your blood more likely to clot)
  • have inflamed varicose veins (phlebitis)
  • previously had blood clots or have a family history of blood clots
  • are pregnant or have recently given birth
  • have a long-term (chronic) medical condition, such as heart or lung disease, or diabetes

How to lower your risk of DVT

Your doctor or nurse assesses your individual risk of getting DVT. To reduce your risk, try to:

  • stay active. If you cannot walk, move your legs, ankles and feet around as much as possible
  • drink plenty of fluids to avoid becoming dehydrated (unless you are told otherwise)

Medicine to lower your risk of DVT

Your doctor might prescribe a medicine that thins your blood and stops it from clotting as quickly as normal. This is called an anticoagulant. It can be taken as a tablet or sometimes given as an injection.

If you need an injection of anticoagulation medicine, the doctor or nurse will explain how to do this safely.

If you have an injection, you may get some discomfort and bruising around the injection site. This should improve when the injections stop. It is rare to have problems with bleeding after the injection.

If you have any abnormal bleeding, contact a GP. In an emergency, go to your nearest emergency department (A&E).

We want to involve you in decisions about your care and treatment. If you decide to have treatment for DVT, we ask you to sign a consent form. This says that you agree to have the treatment and understand what it involves.

If you would like more information about our consent process, please speak to a member of staff caring for you.

Ref number: 4288/VER2
Last reviewed: August 2019
Next review: August 2022

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Contact us

If you have any questions or concerns, please call the emergency department at St Thomas’ Hospital.

Phone: 020 7188 2127 (24 hours)

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Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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