Blood clots can cause serious damage to our bodies, but they are often preventable says Dr Mel Wynne-Jones


Do you know how to cut your risk of a blood clot? ©iStock

Venous thromboembolism (VTE) includes deep vein thrombosis (DVT) and pulmonary embolism (PE), and affects two people per 1,000 each year. In DVT, a blood clot develops in a deep vein (usually in the leg, but sometimes in the brain, arm or trunk).

PE means part of the clot detaches and travels to the lungs, blocking blood flow, sometimes fatally.

The causes

Over half of those who develop DVT have identifiable risk factors. These include a personal or family history of VTE, being older, pregnant or immobilised (travel, illness, injury or an operation, especially one involving the lower body), taking hormones (oral contraceptive pill or HRT), and dehydration.

People are also more at risk if they smoke, are obese, have varicose veins, heart failure or cancer, or blood that clots more easily – for example, antiphospholipid syndrome or inherited thrombophilias.

The symptoms

VTE may have no symptoms at all, but DVT typically causes pain, redness and swelling. Your calf may feel hot and hard.

But this can also be due to cellulitis (infection) or phlebitis, which makes skin and veins feel sore, hard and red.

A PE may cause sharp chest pain that makes it hurt to breathe, breathlessness, faintness, palpitations, a cough and/or blood in the sputum.

These symptoms can also be caused by other conditions, such as chest infections.

Tests you may need

Blood tests may detect clot by-products (D-dimers), low blood-oxygen levels or a blood disorder/antiphospholipid syndrome.

An ultrasound scan of your calf may reveal a DVT; plethysmography (checking blood flow) or a venogram (X-ray after a special injection) may be needed, too.

If a PE is suspected, you’ll need a chest X-ray, a heart tracing and a lung scan or CT pulmonary angiography (CTPA).

CTPA uses complex X-rays to look at lung arteries.

You may also be tested for VTE-linked conditions.

Your treatment

You may need oxygen, painkillers and treatment for underlying causes or other conditions.

Inferior vena caval filters can be used in an emergency or for recurrent PE. These act as sieves to stop blood clots reaching the lungs.

Treatment is aimed at preventing more clots from forming or spreading. Initially this will be daily injections of heparin anticoagulant into the skin of your tummy.

You’ll also be given ‘blood-thinning’ drugs, such as warfarin which requires regular monitoring blood tests to minimise bleeding, or a NOAC (new oral anticoagulant) which doesn’t.

You’ll need these for at least three months or possibly even for the rest of your life,  if VTE is likely to reoccur.

You’ll also need to wear compression stockings for two years to prevent long-term calf swelling, discomfort or ulcers (post-thrombotic syndrome).


NICE, the National Institute for Health and Care Excellence, recommends that people undergoing certain operations, or who break a leg, should stop taking any hormones, wear compression stockings and have heparin injections.

Women at special risk should also be counselled before getting pregnant, and may be offered heparin injections.

If you have a tendency to VTE you may need to take anticoagulants indefinitely; aspirin does not protect.

5 Ways to reduce your risk

1. Know your personal risk factors and follow recommended precautions if you’ve had VTE or are at increased risk.

2. Keep active, don’t smoke and lose weight if you’re obese.

3. Wear support tights if you have varicose veins, and report redness, soreness or swelling immediately.

4. When sitting or travelling by plane, coach or car, point toes up and down regularly to stretch and pump calf muscles. Walk around whenever possible.

5. Longer journeys increase risks. Limit alcohol, which can trigger sleep (immobility) and dehydration (which makes blood sluggish).