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Deep-vein thrombosis – what is it and what are its symptoms?

Posted: 06/03/2020


Throughout March 2020, charities and public health organisations across the UK are aiming to increase awareness of deep-vein thrombosis (DVT) and the serious and potentially fatal complications that can arise if it is not diagnosed and treated early.

What is a DVT?

Many air travellers wear compression or ‘anti-embolism stockings’ when flying and regularly walk up and down the aisles on a long-haul flight to try to prevent DVT. The ‘worried well’ may even ingest half a self-prescribed aspirin despite there being insufficient medical evidence to support the view that this will prevent DVT on a long-haul flight in the otherwise fit and healthy.

So what should we know about DVT and why should we be more concerned?

DVT is more commonly known as a blood clot. It is a frequently occurring medical condition which can potentially be fatal if the clot is not diagnosed and treated. Blood clots do not discriminate and affect one in every 1,000 people in the UK each year.

Deep veins refer to the large vessels in the centre of a limb surrounded by muscle, as opposed to superficial veins. A DVT typically occurs in the slow, sluggish venous circulation of the lower limbs or pelvis, although it can occur elsewhere.

Factors affecting DVT occurrence

The following factors may increase the likelihood of an individual developing DVT. These include:

  • Prior history of DVT or inherited tendency of DVT
  • Obesity with a BMI over 30
  • Stroke – due to immobility and increased prothrombotic activity
  • Pregnancy (one in 1,000 women will suffer DVT in pregnancy and the risk of developing DVT is five times greater for pregnant women than non-pregnant women)
  • Those on oestrogen-containing medicines such as HRT or the combined contraceptive pill
  • Those over the age of 65
  • Long periods of immobility (travel or bed rest)
  • Recent major surgery (hospital-acquired thrombosis).

Although eight out of ten people with DVT will not show any obvious signs or symptoms, when they do present, the most common features of DVT include:

  • Painful swelling, usually in the calf or legs
  • Discolouration (pale blue or reddish purple)
  • Abnormally hot skin.

How is DVT diagnosed?

Two tests are used to confirm a diagnosis of suspected DVT. The first is known as a D-Dimer, a simple blood test to monitor the body’s activity for breaking down clots.

If the D-Dimer is positive, imaging may be performed. This second test could either be an ultrasound scan (sometimes known as a Doppler), a venogram, or a magnetic resonance direct thrombosis imaging (MRDTI).

A venogram involves injecting dye into the foot which is then followed by x-ray as it travels up the leg. If it reaches a clot, the flow of the dye will be disrupted and will be visible on the x-ray. An MRDTI can detect clots without the need for dye or x-rays.

DVT prevention

People with one or more risk factors or a single high-risk factor such as recent hip or knee surgery may be prescribed small doses of anticoagulants to reduce their risk of DVT. This is known as thromboprophylaxis.

Whenever travelling for longer than three hours, regular calf exercises are recommended as well as regular walking whenever possible and drinking plenty of water.

The use of compression stockings is also advised. These work by putting gentle pressure on your legs and ankles to help blood flow. Medical advice should be sought to ensure compression stockings are the correct size and class.

Treatment for DVT

If a diagnosis of DVT is confirmed, anticoagulants are prescribed to prevent the clot from growing and to stop any new clots forming. The most common drugs prescribed are heparin and warfarin.

Despite treatment, 30% of people who suffer a DVT will go on to develop further problems such as post-thrombotic syndrome or venous ulceration within the following 10 years.

Pulmonary embolism (PE)

One of the major concerns about DVT is that the clot becomes dislodged. When a fragment, or indeed an entire clot comes away from the deep vein, it returns with the normal flow of blood back to the right side of the heart where it is then pumped into the pulmonary circulation, the lungs. The fragments of clot can become stuck and cause pulmonary emboli (PE) that block blood flow to the lungs.

Death from a PE is due to acute right heart failure. The heart cannot cope with the sudden increased pressure and will start to beat faster to try to overcome this. People suffering from PE will complain of chest pain and shortness of breath, may cough up blood or suffer a loss of consciousness. They may also feel dizzy and clammy.

Between 2013-2015, the average death rate per year arising from venous thromboembolism was 12,640 in England. Pulmonary embolism therefore remains a clinically significant cause of mortality requiring both awareness and preventative action.

The clinical negligence team at Penningtons Manches Cooper has acted on behalf of families who have suffered the devastating consequences of either delayed diagnosis or delayed treatment of DVT and PE which have resulted in cardiac arrest, hypoxic brain injury and death.

However, if detected early, venous thromboemboli are treatable and preventable. People are encouraged to seek medical advice if they suffer from any of the above symptoms, particularly after surgery or a long-haul flight.

#spottheclot #stoptheclot


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