Blood clots

Reducing the risk of a blood clot from surgery

This page is about the care and treatment of people who are at risk of developing a blood clot because they are having an operation that requires an overnight stay in hospital. It explains advice from NICE (the National Institute for Health and Clinical Excellence) and is closely based on the leaflet provided by NICE.

About blood clots
When you sit still or lie down for a period of time blood moves around your body more slowly, this can trigger a blood clot to form. When a clot forms in one of the ‘deep veins’ in your leg, thigh, pelvis or arm it is known as deep vein thrombosis (DVT).

The blood clot itself is not life threatening, but if it travels to another part of your body it can cause problems – this is called a venous thromboembolism (VTE). If the clot travels to the lungs it is called a pulmonary embolus (PE) and it can be fatal. If a blood clot does travel it can still cause damage to your veins.

Risks for forming a blood clot
Everyone who has an operation is at risk of developing a blood clot but some people have extra  ‘risk factors’ that make them more likely to develop one. Your doctor should assess which risk factors apply to you.  A blood clot may develop in the body at any time during or after an operation.

Example risk factors for developing blood clots

  • You or a member of your family has had a blood clot before.
  • You have cancer.
  • You have longstanding problems with your heart or lungs.
  • You are on the combined contraceptive pill or taking HRT.
  • You have inflamed varicose veins (phlebitis).
  • You are obese (you have a body mass index of 30 or more).
  • You are unable to move around.
  • You take a journey of more than 3 hours in the 4 weeks before or after your operation (for example, on an aeroplane or train).
  • You are over 60.
  • You have a disorder that makes your blood more likely to clot.
Reducing the risk
All patients staying in hospital after thoracic surgery have devices on the legs and injections to thin the blood, unless there is a reason not to have these. We will also keep you well hydrated, if you cannot drink much a drip may be required.

The devices that reduce your risk of developing a blood clot work by encouraging your blood to circulate around your body. Compression stockings are tight stockings specially designed to reduce the risk of blood clots. The stockings squeeze your feet, lower legs and thighs, helping your blood to move around your body more quickly. Your nurse will show you how to wear them correctly. It is important to wear the stockings as much as possible until you are back to your usual level of activity.

Heparin is the most common medicine used to prevent blood clots. This is given by an injection on the abdomen in the evening.

Inflatable compression devices go around your legs (and sometimes your feet) and inflate automatically at regular intervals. They apply pressure when inflated which keeps your blood moving around your body. These are used whilst you are asleep in theatre.

You are still at risk of developing a blood clot in the days and weeks after your operation. This risk continues until you have recovered from your operation and you are back to your usual level of activity. Your physio exercises are good for your lungs and to prevent blood clots. If you cannot move around, leg exercises should be arranged for you. You should also avoid long periods of travel for 4 weeks after your operation to reduce your chances of developing a blood clot.

What are the signs of a blood clot?
There are certain signs to look out for after your operation that could mean you have a blood clot. You should contact your doctor if you experience any of the following in the days or weeks after your operation:

  • You have pain or swelling in your leg.
  • The skin on your leg is hot or discoloured (red, purple or blue).
  • Your feet are numb or tingling.
  • The veins near the surface of your legs appear larger than normal or you notice them more.
  • You suddenly become more short of breath.
  • You feel new pain in your chest, back or ribs which gets worse when you breathe in deeply.
  • You start to cough up blood.