Every year, many thousands of people in the UK develop a blood clot in a vein. It's known as venous thromboembolism (VTE) and is a serious, potentially fatal, medical condition.
VTE is the collective name for deep vein thrombosis (DVT) and pulmonary embolism.
Although serious, most blood clots can be completely avoided. The key is to be aware if you're at risk and take some simple preventative steps.
This article concentrates on blood clots in a vein. If you want information on blood clots in an artery, which is a common cause of heart attack and stroke, you can read more in our section about arterial thrombosis.
Who gets blood clots?
Although it can happen to anyone, you're more at risk of develping blood clots if you can't move around very much or if you're unwell.
You've probably heard of blood clots linked to long-haul plane journeys or the contraceptive pill, but you're much more likely to get a blood clot after going into hospital. In fact, about two-thirds of all blood clots occur during or just after a stay in hospital.
Read more about how and why blood clots occur.
Hospital-acquired blood clots
In 2005, a House of Commons Health Committee report stated that every year in England an estimated 25,000 deaths occur as a result of hospital-acquired VTE.
The report also stated that the estimated number of deaths due to VTE, "is more than the combined total of deaths from breast cancer, AIDS and traffic accidents, and more than 25 times the number who die from MRSA."
The government recognises that deaths from hospital blood clots are preventable and has recommended that all patients admitted to hospital should be assessed for their risk of developing blood clots and, if necessary, protection should be provided.
Following the government's recommendation, a national VTE Prevention Programme has been put in place to try to reduce the number of deaths caused by VTE acquired in hospitals. The programme includes an analysis of all hospital-associated blood clots to identify problems, assess outcomes and improve prevention.
The VTE prevention programme has already had some positive results. For example, at London’s King’s College Hospital, where the programme has been implemented, there's been 20% less hospital-related blood clots and a 40% reduction in events associated with inadequate preventative treatment.
Am I at risk?
When you arrive at hospital, you should be checked for your risk of blood clots. Hospital staff will record your age and weight and ask you about your general health. The assessment will also take into account the reason for your hospital stay.
Your risk of clots is likely to be higher, for instance, if you're having a major operation, if you're going to be confined to bed for long periods, or you're very overweight.
Some people also have certain 'risk factors' that make them more likely to get a clot while in hospital. These include women who take the combined contraceptive pill or HRT, women who are pregnant or who have recently had a baby, if you're over 60, or if you've had a previous blood clot.
If the assessment shows that you're at risk of a blood clot, you should be offered preventative treatment. The options include blood-thinning drugs, compression stockings, or foot pumps to keep your blood circulating and help prevent any clots forming.
Hospital staff should check whether bleeding might be a problem before offering you a drug to help prevent a clot.
If you've been admitted to hospital and you haven't had your blood clot risk checked, it's important that you ask a doctor or nurse. Equally, if you've been told you're at risk of clots and have been given medicine, stockings or other devices, it's important that you understand how to use them properly.
Don't be afraid to ask hospital staff about reducing your risk of blood clots - it could save your life.
Questions you might like to ask your healthcare team about blood clots are:
- am I at risk of blood clots?
- how likely am I to have bleeding problems?
- what happens if I have problems with a drug or treatment I am having to help prevent clots?
How can I help myself?
You can help yourself before coming into hospital by:
- losing any excess weight
- stopping smoking
- talking to your doctor if you take HRT or the combined contraceptive pill – you may need to stop them a few weeks before your operation
While you're in hospital, you will reduce your chances of a blood clot if you:
- drink plenty of fluids to keep hydrated
- wear your compression stockings day and night (except when you're washing)
- wear any other compression devices you've been given
- take any blood-thinning medicines you've been prescribed
- get up and move around as soon as you're advised to
How to tell if you have a blood clot
The term venous thromboembolism (VTE) covers two types of venous blood clots:
A DVT is a blood clot in a deep vein, usually in the leg. You may have no symptoms at all with a DVT, or you may get a cramping pain, redness or swelling in the leg.
Read more about the symptoms of DVT.
Occasionally, a clot in a vein dislodges and forms what is known as an embolus and moves to the lungs. This is a more dangerous condition, called pulmonary embolism (PE). Known as the 'sudden killer' because it can strike so quickly, PE can cause breathlessness, chest pain and sudden collapse.
Read more about the symptoms of PE.
If, after you've left hospital, you develop any of the symptoms of a blood clot, or you suspect you may have a blood clot, see your GP or go to your nearest accident and emergency (A&E) department as soon as possible. Blood clots can be treated if they're spotted in time.
Read more about the treatment of blood clots.