Blood Clot

A blood clot is when blood forms into a solid deposit in a vein or artery. If it occurs in the veins in the legs, it’s called deep vein thrombosis (DVT), and if a clot travels to the lungs, it’s known as a pulmonary embolism (PE), which can be very serious. 

  1. DVT causes tenderness and pain, usually in the back of the calf or thigh
  2. Can be caused by remaining inactive for long periods
  3. Medication can prevent complications

It’s important to speak to a doctor if you think you could have symptoms of DVT, such as swelling or pain in the legs. If you are unable to get to a doctor in person and want to speak to someone online, our video service can help. 

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What is a blood clot?

A blood clot is a hard collection of blood. Clotting is an essential mechanism to prevent external bleeding when we sustain a wound. However, if too much blood collects in one place inside a vein, this can lead to a problem called deep vein thrombosis (otherwise known as a clot in a vein or DVT). Clots typically manifest in veins in the legs. 

In some cases, sections of a blood clot can break off and travel through the bloodstream. When this occurs, and a deposit reaches the lungs, it’s known as a pulmonary embolism (blood clot in the lung or PE). This is a very serious condition, requiring emergency treatment, so it’s important to address clots when they first materialise to ensure this doesn’t happen.

How common is a blood clot?

Blood clotting helps to repair injured blood vessels. Usually platelets form a plug at the injured area, and chemicals are released to form a mesh, to clot the blood. However, this can become problematic if the clot begins to grow or if it’s passed to an artery in the lung.

Blood clots have a prevalence of around 1 in 1,000 people. The incidence rate increases exponentially with age: only around two or three people per 100,000 people get a blood clot between 20-30 years old, whereas around 500 per 100,000 people get a blood clot over the age of 85. In the last few years the incidence rate has risen, and this can be put down to an ageing population and more testing for DVT.

What complications can a blood clot cause?

A possible complication of DVT is a pulmonary embolism. According to NHS Inform, about 1 in 10 people with DVT will go on to have a severe pulmonary embolism. 

Less severe cases of PE (where only a small clot enters the lung) might be treated in a similar way to DVT. But if there is evidence to suggest that a larger clot has entered the lung, which might include symptoms such as difficulty breathing or chest pain, emergency treatment will be necessary. Suspected symptoms of a PE should warrant urgent medical attention, as it can result in serious complications such as heart failure if it is not treated effectively.

DVT can also lead to a long-term condition known as post-thrombotic syndrome, which can cause chronic pain, a rash on the calf or thigh, or ulcers. 

However, if you have leg symptoms such as swelling or tenderness which you think could be a sign of DVT, but are not sure, our online video consultation service may be able to help you. They can tell you if your symptoms warrant further investigation, and provide advice on what to do next. They can also offer guidance if you have had a blood clot before, and want to speak about your ongoing treatment plan.

Page last reviewed:  15/06/2020
Diagnosis and treatment

How is a blood clot caused?

The movement of blood in the veins is helped by muscle action; immobility and inactivity cause the flow of blood to slow down, and this may lead to the formation of a clot. Clots may develop if you’ve had an operation and are having to lie or sit down for long periods, or if you’re living with a condition that causes immobility. People who have suffered from heart failure, cancer or are obese are also at greater risk of blood clots. 

How is a blood clot diagnosed?

A blood clot in the leg (deep vein thrombosis or DVT) can be diagnosed through a combination of physical examination and testing. A DVT will sometimes form in a vein below the knee, which will cause pain and tenderness in the calf, as well as a significant swelling. This swelling will become hot, and red in colour as blood is passed to the outer veins due to a blockage. 

However, it is also possible for a DVT to be asymptomatic, and not lead to any noticeable signs unless it becomes a PE; in this event, emergency treatment will be necessary. 

Will I need tests?

If a doctor thinks that symptoms could be due to another condition, some tests may be necessary. Muscle strains, cramps and skin infections can present similar symptoms to a DVT, so it’s important to rule these out. 

The two most common tests that a doctor will conduct are the D-dimer blood test and a duplex doppler. The D-dimer test detects the amount of protein fragments in the blood which indicates a clot. The doppler test uses ultrasound to show the flow of blood in the body. If a pulmonary embolism is suspected, a doctor may decide to get an echocardiogram, or a CTPA scan. This is a CT scan that looks specifically at the arteries in the lungs.

How is a blood clot managed?

Anticoagulation therapy is the most common treatment for a DVT. This stops the blood from forming clots as easily, and prevents them from developing into a PE. 

There are various types of anticoagulant drugs, the most renowned of which is warfarin. Other medications include dabigatran, rivaroxaban or apixaban.

A doctor may also recommend the use of compression stockings. They apply pressure to the veins to facilitate the flow of blood.

A PE can be treated with anticoagulants, but this usually requires hospitalisation, particularly if there are serious indications such as a fast heart rate or low blood pressure.

Page last reviewed:  15/06/2020
Questions and Answers

How is a blood clot treated?

A blood clot can usually be treated with anticoagulants, which will stop the clot building and relieve the swelling. This allows the body to break down the clot so that blood can flow normally again. Compression stockings may also be used to help the flow of blood. 

Less severe cases of a pulmonary embolism can be treated in the same way as DVT. However, severe cases will require treatment in hospital.

How long will it take for me to recover?

It can take between a few weeks and a few months for the body to completely dissolve a blood clot, during which time anticoagulants will need to be used. A course of anticoagulants should be taken for up to three months to prevent a clot forming again.

Can I consult a doctor about blood clots online?

If you’re short of breath or having chest pain, or experiencing any other symptoms of a pulmonary embolism, you should go to hospital right away.

Our online video consultation service is available if you would like a doctor to examine any symptoms which you think could be a blood clot in a leg. Our UK doctors will be able to provide advice on managing symptoms and let you know if you need a physical examination or further treatment. Book an appointment at a time that suits you. 

Page last reviewed:  15/06/2020

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