Preventing blood clots
Advice on preventing blood clots at home or in hospital.
The formation of a blood clot or 'thrombus' inside
a blood vessel is called thrombosis; you may have
heard the term DVT or deep vein thrombosis that most commonly
occurs in the leg veins.
A complication of developing a clot is it can break away
from where it formed and travel to another part of the body, where
it may become lodged in another blood vessel and restrict the blood
flow. When a clot travels it is known as an 'embolus' and
when it gets stuck in another blood vessel it's called an
'embolism'; you may have heard the term PE or pulmonary embolism,
which is a clot in the lungs. VTE or venous thromboembolism
is a term that includes both DVT and PE.
How can blood clots form?
There are two reasons that a clot might form
- Changes or damage to the blood vessels:
If there is pressure on a vein a clot can form.
Pressure on the vein might be caused by immobility, surgery
or long distance travel.
- Problems with the blood: Blood problems
can be inherited, caused by drugs you are taking, acute illness
(such as an infection, cancer, respiratory failure, heart failure),
or pregnancy. If you are dehydrated, the blood can get
'sticky' which can increase the risk of blood forming a clot.
There are a number of factors that can increase a person's
chance of developing a blood clot.
- Developing a clot in the past or having a family history of
- Major surgery, particularly orthopaedic (bone) surgery
- Major trauma or leg injury
- Aged over 60
- Cancer or chemotherapy treatment
- Acute illnesses
- Being immobile
- Pregnancy, some types of contraceptive pill or hormones
- Faulty blood clotting e.g. thrombophilia
If you have to come in to hospital
When you are admitted to hospital, nurses and doctors will
assess you to see if you are at risk of developing a clot and will
repeat the assessment every 48 to 72 hours. You might hear
this referred to as a VTE assessment (VTE stands for venous
thromboembolism - a clot in a vein). If you are assessed to
be at risk of developing a clot you will be offered the appropriate
Prevention can include one or all of the following:
- An injection of heparin called Dalteparin (Fragmin)
- Anti-embolism stockings, often called 'TEDS'
- Leg pumps or 'flowtrons'
To help prevent clots at home or after you have been in
- Walk around as much as possible or, if you are not very mobile,
exercies you legs while you are in bed or sitting in a chair.
- Drink plenty of fluids
- If you are at risk, wear anti-embolism stockings when you are
on long haul journeys
There are information leaflets available on admission and
discharge from hospital.
Signs and symptoms of a clot
Typical symptoms of a deep vein thrombosis (DVT) include
swelling, pain, tenderness in the calf and sometimes heat and
redness when compared to the other leg.
The typical symptom of pulmonary embolism (PE) is shortness of
There are other causes of painful swollen calves and difficulty
in breathing. If you are concerned contact your GP, visit NHS Direct or call on 0845 45 47 or in
an emergency go Accident and Emergency.
For more information visit the NHS.uk page