Preventing hospital associated blood clots

Information for patients and carers

Who is at risk?

Any adult who is admitted to hospital is at risk. Other factors that put people at greater risk include the following:

  • have undergone surgery lasting more than 30 minutes
  • are aged over 60
  • have experienced significant periods of immobility or a reduction in your usual level of mobility
  • are taking certain medications, such as HRT, oral contraception antipsychotic therapy  or chemotherapy
  • are pregnant or have had a baby within the last six weeks
  • have cancer or are undergoing cancer treatment
  • are obese with a BMI greater than 30
  • have had a previous venous thromboembolism (VTE)
  • are dehydrated
  • have certain blood diseases
  • have a family history of thrombosis
  • have an inherited or acquired clotting problem
  • are suffering from an acute medical illness
  • have more than one medical condition such as heart disease, diabetes or respiratory illness
  • have inflammatory disease such as Crohn’s or rheumatoid arthritis
  • have undergone long-haul travel of more than four hours within four weeks before or after your hospital stay.

Symptoms of deep vein thrombosis (DVT)

DVT is a blood clot usually in one of the veins of the leg or pelvis. Symptoms include swelling of the calf or thigh, usually accompanied by pain, heat or redness, or difficulty in weight bearing. However many DVTs produce no, or only some of these symptoms.

Symptoms of a pulmonary embolism (PE)

PE occurs when a piece of blood clot breaks off into the bloodstream and blocks one of the blood vessels in the lungs. Symptoms include difficulty in breathing or shortness of breath, coughing up bloodstained sputum or chest pain that is often worse on breathing in. These can sometimes be accompanied by symptoms of DVT.

Going home

Until you return to your usual level of activity, you may need to wear anti-embolism stockings after you go home. Your nurse will tell you how to put them on and what you should check your skin for, who to contact if you have a problem and when to stop wearing them.

VTE can happen at any time during a stay in hospital or in the weeks after leaving hospital. If you experience any VTE symptoms or bleeding once you are at home you should seek urgent medical advice from your GP, by contacting 111, or your nearest emergency department


Preventing blood clots is a priority for our hospital staff. Many people think that going on a long flight is the biggest risk factor for suffering a VTE. Unfortunately, the risk of getting a blood clot in hospital is far greater than from a long-haul flight. About two-thirds of all blood clots happen during or in the 90 days after a stay in hospital.

Although the risks are small, the consequences can be serious and lead to long-term medical problems such as permanent swelling in the leg, varicose veins and even leg ulcers.

Our doctors, nurses, pharmacists and other teams all play an important role in keeping you safe.

There are a number of measures that will help minimise your risks of getting a hospital-associated VTE. This leaflet explains what you can expect while you’re in hospital and aims to answer some of the initial questions you may have. If you would like more information or have any concerns, please speak to a member of your healthcare team.

Most DVTs can be prevented safely and effectively. On admission to hospital, each patient has their risk for VTE assessed and, if necessary, preventative measures advised. We will also assess if any of the preventative measures may not be suitable for you.

As with any treatment, there is the possibility of adverse effects. Please talk to a nurse, doctor or pharmacist if you think the treatment is causing you any problems.

You may be given one or more of these treatments:


Drugs used to prevent and treat blood clots are called anticoagulants. While you are in hospital it’s likely that you will be given anticoagulant medication in the form of an injection, which is of animal origin and may be of concern to you, but sometimes it will be in tablet form instead. Your healthcare professional will advise which is best for you.

In some situations the medication may need to be continued once you have left hospital. If you need to continue with the medication at home, you will be your nurse will show you how to administer injections and equipment will be provided to take home

Anticoagulants reduce your risk of developing a clot, but they may also increase your risk of bleeding. Because of this, we assess whether bleeding might be a problem during your hospital treatment. If your risk of having problems is higher than your risk of VTE, you will not be given an anticoagulant to help prevent VTE, but you may be given other treatments instead.

Anti-embolism stockings (AES)                                                               

You may be measured and fitted with anti-embolic stockings (AES) which are usually knee length. You should be shown how to wear them and told to tell a

healthcare professional about any new pain or discomfort in your feet or legs. Your stockings should be removed for a short time twice a day so that you can have a wash and check for any skin problems.

Compression devices                                                               

These are inflatable sleeves that are fitted around the leg or foot and kept in place while you are immobile in your hospital bed. They inflate at regular intervals and the pressure increases the flow of blood back to the heart.

Keep moving                                                               

It is important to move around as soon as possible, especially after surgery. This is sometimes the only measure that needs to be taken.

Leg exercises                                                               

Point your toes down and bend the foot up at regular intervals as this helps to pump blood back to the heart. Do this at least ten times an hour when you are inactive.

Drink plenty of fluid                                                                 

Dehydration can also increase your risk of DVT, so make sure you drink enough fluid.

About blood clots

Blood normally flows quickly and uninterrupted through our veins. Sometimes however, clots can form that either reduce the blood flow or stop it completely.

A deep vein thrombosis (DVT) is a blood clot in a deep vein, usually in the leg or pelvis. The common cause is immobility—for example not moving around as much as you usually do while you’re unwell or recovering from an operation. Long-term discomfort and swelling of the ankle and calf can occur in some people following a DVT. This is called post-thrombotic syndrome.

A pulmonary embolism (PE) is when all or part of the DVT becomes dislodged and travels with the natural flow of blood back to the lungs. The clot then gets stuck in the blood vessels of the lung. This may be fatal.

DVT and pulmonary embolism together are known as venous thromboembolism (VTE).

Blood services (anticoagulation and phlebotomy)