Blood Clots – Essential Information on Thrombosis.

Blood clots and thrombosis. Essential information.Hospital-acquired infections and superbugs like MRSA and c. diff (clostridium difficile) often come up as killers in the newspaper and TV news headlines.  But what about thrombosis?  It kills 37 times more people than MRSA.  For example in the UK alone (and this is an international problem) it kills up to 32,000 people per year.

But it’s largely (but not totally) preventable.

What is thrombosis – a blood clot?

Thrombosis is a blood clot in a vein.  They commonly start in one of the long veins of the leg and are called Deep Vein Thrombosis, or DVT.  Parts of the clot can then break off from this primary site, travel in the circulation and get stuck in the veins in the lungs.  Here they are called Pulmonary Embolism or PE.  This can be life threatening.

How do you get a DVT or a PE (blood clot)?

Stories about young people (often women) who get DVTs after a flight make the news because they’re relatively rare.

When you’re in hospital, having had an operation or being unwell, you’re less mobile than normal.  The blood in the veins of the legs depends on the calf muscles working as we move

Blood Clots - essential information.about to help with its return to the heart.  There are also valves in the veins that help with this process.

However when the blood isn’t being effectively pushed back to the heart because you’re less mobile than usual, it can pool and become a bit sticky – especially if you’re a bit dehydrated or taking certain meds.  These factors all conspire to create a clot.

How do I reduce the risk of blood clot?

When you go into hospital you should be assessed for your individual risk of thrombosis as there are certain risk factors that will then determine what sort of preventative treatment you should have.

Risk factors for thrombosis are things like: being over 40 years of age, having an operation (especially one on the abdomen, pelvis, legs/hips), trauma (fractures), some medical conditions such as diabetes, cancer and its treatment, immobility during your hospital stay and recovery, varicose veins, being very overweight, pregnancy, smoking and having had a previous DVT.

There are different levels of risk for clot depending on the combination of risk factors that you have.

Clot prevention measures in hospital include anti-thrombosis stockings. You will be measured for these so that you get the right size; they should be tight fitting and may be either to the knee or to the top of the thigh.  If you can, keep these smooth on the legs as wrinkles can act like a tourniquet.

If your risk assessment shows you are at greater risk you should also have low-dose heparin injections that help to keep the blood thin.  These are given once a day into the fatty tissue of the stomach and you may be taught how to self inject in preparation for doing them at home.

There are also inflatable leg ‘boots’ if you are at very great risk and immobile for a long time.Blood clots - essential information.

You can help yourself by:

  • Being as mobile as possible (getting out of bed and walking about) as soon as you’re advised that it’s safe to do so.
  • Also be sure to drink enough, which will mean you need to get up to use the bathroom – exercise in itself!
  • Before you have a planned stay in hospital, lose weight and stop smoking if you need to.
  • If you can’t get up and about then do regular leg exercises – circling the ankles, flexing and stretching the feet and toes.  These are similar to the exercises that are advised on long haul flights.
  • Some people find it difficult to challenge their medical team and to ask questions about their care when they’re in hospital – you’re in your pyjamas and feeling unwell, it’s no surprise!  If you feel you or your loved one might be at risk from a blood clot but don’t know if you have been assessed, simply say that you’ve been reading about DVTs on the internet and want to know more, are you at risk, have you had a risk assessment etc.

If you’re not happy and/or have any of the risk factors we mentioned above then question a little more and ask for the rationale behind the answer you’ve been given.  It may be that the hospital doesn’t have a thromboprophylaxis (say thrombo-proffill-axis) policy but that’s not a good enough answer.  And never believe a doctor or surgeon who says his patients don’t get DVTs.

If you are going to have a planned stay in hospital then ask about these things before you decide that’s the hospital you want to go to.  This is the same for the UK under Choose and Book or the private system and in the US.

How do I know if I have a blood clot?

DVT is difficult to diagnose.  Commonly though, the leg may be:

  • hot,
  • swollen,
  • tender and painful.
  • Not everyone has all these symptoms and there are other causes of them.

Various scans and blood tests are used to determine the likelihood of a clot and if it’s confirmed then you will have blood thinning injections (heparin) and then take blood thinning tablets (warfarin) as the body gets on with the job of safely dissolving the clot.


Thrombosis can be life threatening but it is preventable.  Before or during the very early part of your hospital stay you should have a risk assessment and then be given the appropriate anti-clot measures – stockings +/- heparin +/- inflatable boots – for your degree of risk.

Remember to ask, just as you would about any other aspect of your care.  A good doctor or nurse won’t be worried by your questions and will encourage you to do all the right things to ensure your good recovery.

Elspeth Raisbeck