What is it? What are the symptoms? What are the treatments?

What is thrombosis?

Thrombosis is the term for a blood clot in a blood vessel, and can be venous (venous thromboembolism, or VTE, when the clot is in a vein) or arterial (when it's in an artery). Arterial thrombosis usually occurs when there is aterosclerosis, which is the clogging of the arteries.

One of the commonest VTEs is the deep-vein thrombosis (DVT), which usually occurs in one of the larger veins in the lower leg. If a piece of an original blood clot becomes detached and travels around the bloodstream to another part of the body, it's known as an embolism. One of the commonest embolisms is a pulmonary embolism (PE), where a detached piece of blood clot lodges itself in a lung.

Blood clots are a common cause of death in England, affecting around 25,000 people a year. They interfere with the flow of blood and, if not treated, can cause serious problems, including heart attacks and strokes.

Although they can often be treated if they are spotted in time, prevention is a much better option. You may need to make some lifestyles changes to reduce your risk of thrombosis, such as stopping smoking, eating more healthily and taking more exercise.

Anyone can be affected by blood clots, although your risk increases after you hit 40. You're also at higher risk if you have a family history of thrombosis; if you're immobile for stretches of time – such as on a long-haul flight or in hospital; if you have damaged veins or arteries; if you're on the contraceptive pill and if you have certain medical conditions.

Expectant and new mums are also at increased risk of a blood clot in the vein, although the extent of the risk depends on age, weight and how many previous pregnancies they've had. You're ten times more likely when you're expecting than a woman the same age as you who isn't pregnant to get a thrombosis.

What are the symptoms of Thrombosis?

Blood clots can have few or no symptoms, which is what makes them dangerous. However, symptoms of a venous thromboembolism include warm, reddened, swollen skin in the affected area; a feeling of heaviness in the area; prominent veins; itching and mild fever (temperature of 38°C or above), although you may have all, some or none of these.

With a Deep Vein thrombosis, often the only symptom is pain in the affected site.

If a piece of clot detaches and forms a pulmonary embolism (PE), symptoms include breathlessness, even when resting; chest pain and bringing up blood; fainting; rapid heart beat and bluish skin. This is a medical emergency.

Symptoms of an arterial thrombosis vary, depending on whereabouts in your body the clot is. For example, you're likely to develop symptoms of a heart attack if it's in one of the heart's main arteries, or symptoms of a stroke if it's blocking the blood supply to the brain.

What are the treatments and remedies of Thrombosis?

If your blood clot is in a vein, you'll be prescribed anticoagulant medication, which makes the blood less viscous (sticky) and less likely to clot. You'll probably be given heparin by injection straightaway, as this acts fast to stop further clotting. Then longer term you may be given warfarin, which thins the blood.

If the clot was in your leg, you'll be prescribed compression stockings to reduce swelling and lessen the risk of getting post-thrombotic syndrome, where symptoms including itching, pain, heaviness around the original site, swelling or an ulcer can recur, affecting previous thrombosis sufferers long term. You'll usually be advised to wear the stockings for two years after your thrombosis has resolved.

If you develop a venous thrombosis in pregnancy, you'll be taught how to inject yourself with heparin daily and for six weeks after the birth. The type of heparin usually prescribed in pregnancy is called low-molecular-weight heparin (LMWH), because it can't cross the placenta so it won't affect your baby.

For an arterial thrombosis, medication is prescribed to rectify blood flow to the heart and brain. Alternatively, surgery to unblock the artery or to re-route blood flow around the blockage, may be necessary. There are different methods of surgery depending on where your thrombosis occurred.

Further help

For health advice and information 24 hours a day, 365 days a year, the NHS offers call and web services. You can also visit NHS websites for services, health information and health news at nhs.uk 

  • England – call 111 from any landline or mobile phone free of charge, or visit nhs.uk 
  • Scotland – call 111 from any landline or mobile phone free of charge, or visit nhs24.com 
  • Wales – call 0845 4647 , or visit nhsdirect.wales.nhs.uk 
  • Northern Ireland – visit hscni.net