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Prevention of deep vein thrombosis in lower limb immobilisation

Patient information A-Z

Information for adult patients who have a lower limb injury requiring immobilisation.

What causes a deep vein thrombosis (blood clot)?

Blood clots also known as a deep vein thrombosis (DVT) or venous thromboembolism (VTE) is the presence of a blood clot in the veins (usually of the legs).

DVT’s can cause permanent leg swelling, leg ulcers, aching legs and changes in skin colour of the leg. Some DVT’s can move to the lungs causing a pulmonary embolism (PE) which may cause chest pain, breathing difficulties and even death.

DVT’s often occur in people who are moving around less than they usually do. This can also be a complication of having your limb immobilised following an injury or break in the bone. We know that on average 1 in 50 people who have their limb immobilised after injury will suffer a blood clot.

Certain risk factors will determine if your risk of a clot is higher or lower than this average.

Who is at greater risk of developing a blood clot?

Some patients are known to be at a higher risk than others due to a range of factors:

  • You are over 60 years old
  • You have a personal or family history of bloods clots
  • You have active cancer
  • You have recently had a major operation
  • You have an Achilles tendon rupture
  • You are pregnant or have had a baby in the last 6 weeks
  • You have a disorder which makes your blood more likely to clot
  • You take the combined oral contraceptive pill or hormone replacement therapy
  • You have one or more long term medical condition requiring treatment: heart disease / lung disease / bowel disease / hormone disease
  • You have a body mass index of 30kg/m2 or more
  • You have varicose veins

How will you help me reduce my risk?

There are a number of methods that can be used to reduce a risk of developing a clot. The methods we will use will depend on your level of risk.

Some of the ways that we reduce the risk are:

  • Mobilise as early as possible.
  • Drink plenty of fluids.
  • Medication if you are at a much greater risk, your clinician will talk to you if you require additional medication.

What can I do to reduce my risk of developing a blood clot?

You can help reduce your risk of developing a clot by:

  • Drinking plenty of water or other non-alcoholic drinks to keep hydrated
  • Moving around as much as you can
  • Taking any medication you have been prescribed.
  • Carrying out the following leg exercises with one or both legs
Deep vein thrombosis leg exercise

Lying on your back or sitting, bend and straighten your ankles quickly 10 times.

Keep your knees straight during the exercise to stretch your calf muscles.

Try to do this exercise two or three times an hour.

Please note that these exercises are only for the leg that is not in a cast.

Who can I contact for further advice?

Urgent advice: You must return urgently to the emergency department if you:

  • Develop any permanent leg swelling, leg ulcers, aching legs or changes in skin colour of the leg.
  • Develop any chest pain or breathing difficulties
  • Develop increasing limb pain that is getting progressively worse and is not controlled by simple pain medication
  • Develop swollen, painful, pale or blue coloured and cold toes on the plastered limb
  • Develop any significant bleeding.

If you are prescribed rivaroxaban tablets (or dalteparin injections)

The medication helps to reduce the risk of development of a blood clot in the veins of your injured leg. Both medicines work by increasing the time it takes your blood to clot.

You should take your first dose of medication 24 hours after the plaster or splint was placed on your leg and continue taking it daily until the plaster or splint is removed. In most cases, this is six weeks.

  • You should take the medication at the same time each day.
  • If you accidentally take more medication then you should phone 111 or let your GP know as soon as possible, so they can assess your risk of bleeding.
  • If you miss a dose you should take it as soon as you remember. If it is less than six hours until your next dose, do not take the drug, wait for your next due dose.
  • There is an increased risk of some side effects if you are also taking: Aspirin, clopidogrel or other antiplatelets / anti-inflammatory medication (NSAIDs).
  • If you are already on aspirin, clopidogrel or NSAIDs your clinician may prescribe you a medication to protect your stomach (for example omeprazole 20mg daily) for the duration of treatment with rivaroxaban or dalteparin if you are not already taking this or a similar medicine.
  • Medication should be stored at room temperature out of reach of children
  • If you are scheduled to have surgery on your injured leg, do not take your rivaroxaban the day before or the day of your surgery so that your blood clotting can return to normal.


  • You should take rivaroxaban 10mg (one tablet) once daily.
  • It should be taken with or after food.
  • If you cannot swallow the tablet whole, it can be crushed and mixed with soft food such as apple puree. If you decide to take the medication like this, you must ensure you take the whole tablet. Rivaroxaban is not suitable if you are pregnant or breastfeeding.


  • Dalteparin should be taken once or twice a day. Make sure you know how often to take this medicine.
  • The dose of dalteparin depends on how much you weigh.
  • Dalteparin syringes should be disposed of in a yellow sharps bin. You should be given one of these.
  • For disposal of sharps bins you can check with your local council. You can search on your council website for how to dispose of ‘domestic clinical waste’: they will list participating pharmacies who will take your sharps bin for safe disposal. If you are unable to take the sharps bin yourself, you can arrange for a collection from your local council.

If you have unexpected significant bleeding (nosebleed, blood in your stool or vomit) do not take your medication and return to the Emergency Department for assessment.

Who must you tell that you are taking rivaroxaban or dalteparin?

  • Your GP, in case they need to give you any other medication
  • Any health professional involved in your medical care during the treatment period. i.e. dentist, pharmacist, physiotherapist


If you have any questions about your risk of developing a clot, or about anything in this leaflet please ask your treating clinician, nurse or pharmacist for more information or visit

References and sources of evidence

Low molecular weight heparin for the prevention of venous thromboembolism in patients with lower-leg immobilization (Review), Zee AAG, van Lieshout K, van der Heide M, Janssen L, Janzing HMJ. The Cochrane Collaboration. The Cochrane Library, 2017.

NICE Guideline 89. Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism. March 2018.

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Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151