Every year, 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) – a blood clot in in one of the deep veins in the body, usually in one of the legs

pulmonary embolism – a blood clot in the blood vessel that carries blood from the heart to the lungs

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 is about blood clots in veins. If you want information on blood clots in arteries, which is a common cause of heart attack and stroke, see the topic on arterial thrombosis.

Who gets blood clots?

Anyone can get a blood clot, but you’re more at risk if you can’t move around much or if you’re unwell.

You’ve probably heard of blood clots linked to long-haul plane journeys or the contraceptive pill, but most blood clots actually develop during or just after a stay in hospital.

Your risk is also increased if you:

are over 60 years old

are overweight or obese

have had a blood clot before

are having hormone replacement therapy (HRT)

are pregnant or have recently given birth

are dehydrated

have cancer or are having cancer treatment

have a condition that causes your blood to clot more easily than normal, such as antiphospholipid syndrome

The rest of this topic will focus on blood clots linked with admission to hospital.

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 measures to reduce this risk should be taken when appropriate.

Assessing your risk of blood clots

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 if you have any of the other “risk factors” mentioned above.

If the assessment shows that you’re at risk of a blood clot, you should be offered preventative treatment. The options include blood-thinning medication (anticoagulants) and 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 medication to help prevent clots.

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 medication or treatment I am having to help prevent clots?

Reducing your risk of blood clots

There are things you and the medical professionals looking after you can do before, during and after your hospital stay to minimise your risk of developing a blood clot.

Before coming into hospital

You can help yourself before coming into hospital by:

trying to lose any excess weight

keeping as mobile as you can

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 in hospital

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 offered

get up and move around as soon as you’re advised to

After leaving hospital

You’re still at risk of developing a blood clot in the days and weeks after leaving hospital, so you might be advised to continue preventative measures for a short period. Your care team will discuss this with you before you are discharged.

You may be given compression stockings to wear until you are fully mobile, and you may need to keep using anticoagulants for several weeks. You should also take care to stay as mobile as possible and keep yourself well hydrated.

How to tell if you have a blood clot

Before leaving hospital, you should be told about anything you need to look out for that could suggest you’ve developed a blood clot.

Symptoms of a blood clot can include:

cramping pain, redness, warmth, or swelling in one of your legs – these are symptoms of DVT

breathlessness, chest pain, fainting or coughing up blood – these are symptoms of a pulmonary embolism

If you develop symptoms of 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 treating blood clots.