Deep vein thrombosis

Sometimes a reason cannot be found as to why the blood clot has formed, but risk factors for blood clots include:

• Previous blood clots or a family history of blood clots
• Pregnancy
• Use of the oral contraceptive pill or hormone replacement tablets
• Surgery or reduced mobility (for example, leg plaster casts)
• Long haul flights (and other forms of travel if more than four hours in duration)
• Smoking
• Being overweight
• Increasing age
• Cancer
• Underlying condition of ‘sticky blood’.

Sometimes, you may need some tests to look into why you had the blood clot. If this is needed, your team will refer you to see a specialist.

If you need treatment for a DVT, this will usually be managed as an outpatient, but sometimes your personal circumstances and the type of DVT you have may need admission to hospital.

The main treatment is called an anticoagulant (‘blood thinner’). This is a medicine that causes chemical changes in your blood to stop it clotting easily. It will stop the clot getting larger while your body slowly absorbs it and reduces the risk of further clots developing.

There are many types of anticoagulants, and your health care professional will select the best one for you. This may be as injections or tablets. In all cases, you should expect to receive specific information about the medicine before you leave the hospital.

Occasionally and in very severe cases, other treatments may be needed to remove or break up a blood clot. This might be with a medicine called a thrombolytic (‘clot buster’) or less commonly, with surgery. If you need one of these treatments, you will still need to receive an anticoagulant afterwards.

You will usually be recommended to take the medicine for at least three months. Some people may need to take them for longer or sometimes lifelong. Specialist blood tests may be needed to help with this decision and if needed, we will refer you to a specialist.

The anticoagulant will help stop the clot from getting bigger and may help with the symptoms of leg swelling. The pain and swelling will reduce with time and treatment.

Once you have been diagnosed with a DVT you will be referred to an anticoagulation clinic. The team will check that there are no problems with the medicine you are taking, perform any blood tests if needed and answer any questions that you may have. We may refer you to a general medicine clinic or thrombosis clinic for further investigations if needed.

You must seek immediate medical attention if your symptoms worsen, or if you develop any new symptoms, such as: 

• Chest pain or breathlessness
• Coughing or vomiting blood
• Increased leg swelling

Exercise and rest: You may find that you cannot do as much physical activity as normal due to your symptoms. Avoid long periods of exercise in the first few weeks. If you need a painkiller, paracetamol is considered to be safe to take with anticoagulant medicines. Aspirin and other anti-inflammatory medicines (for example ibuprofen, naproxen or diclofenac) should be avoided, unless under the guidance of your GP. This is because they may interfere with your treatment and potentially increase the risks of bleeding. Other medication: Always check with your GP or pharmacist before taking any medication, including herbal or alternative treatments, to make sure they are safe to take with your treatment.

Diet: Try to eat a healthy, balanced diet and to avoid excessive changes in your weight. Alcohol intake may interfere with your anticoagulant treatment so we recommend that you do not drink more than one to two units of alcohol per day. Speak to a healthcare professional for more advice, especially if you are due to start warfarin. Alcohol can also increase your risk of falls and injuries, which can be more serious if you are taking an anticoagulant.

Travel: Ideally, long distance travel is not advisable for two weeks after your diagnosis. Post-thrombotic syndrome (PTS): This is a common complication of DVT. Symptoms include leg swelling, varicose veins and occasionally leg ulcers. They can occur in 20-50 per cent of cases, but usually with extensive DVTs and the symptoms may vary. These symptoms can be lifelong and compression stocking may help, although you should not wear them until the initial leg swelling has settled. Walking and exercise reduce the risk of developing PTS. 

In general, anyone who has had a DVT (or PE) is at a higher risk of having a blood clot in the future, compared to someone who has never had a blood clot. It is important to tell any healthcare professional that you see, about your history of blood clots, as this may affect your treatment.

Useful sources of information

NHS Choices:

• www.nhs.uk/conditions//bloodclotsThrombosis UK
• https://thrombosisuk.org/index.php

UCLH cannot accept responsibility for information provided by external organisations. 

Emergency Services Division
4th Floor East
250 Euston Road
London NW1 2PG
020 3447 9889