Blood clots

What is a blood clot/venous thromboembolism (VTE)?

Blood clotting is a natural process to stop you from losing too much blood if a blood vessel like a vein or artery is injured. Blood cells called platelets stick together with red blood cells helped by special proteins known as clotting factors. This makes a sticky plug called a clot, or thrombus. Once the injury has healed this clot will dissolve and disappear.

Sometimes a clot can form when it shouldn’t, inside the blood vessel. This can block the flow of blood and is called a thrombosis. 

Blood clots in veins are called venous thromboembolism (VTE). There are two main types:

• Deep vein thrombosis (DVT): this is where a blood clot develops in one of the larger veins deep inside your body. This is usually a vein in your leg but can be a vein in your pelvis, arm or tummy.
• Pulmonary embolism (PE): this is where part of a clot breaks free and travels to your lung where it blocks some of the blood getting to a part of your lung.

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What causes a venous thromboembolism (VTE)?

Blood usually flows quickly through your veins, back to your heart. This is helped by the muscles around the veins. If something slows down this blood flow, or makes your blood ‘stickier’, a blood clot can form.

Lymphoma can cause a VTE for a few reasons. 

• Cancer cells can produce clotting factors which makes the blood stickier.
• Enlarged lymph nodes can press on deep veins slowing the blood flow.
• Lymphoma symptoms and treatment might make you less mobile than normal which slows down the flow of blood in your veins.

Certain lymphoma treatments can also increase your risk of developing a blood clot. These include chemotherapy, surgery and the targeted treatment lenalidomide. Your medical team will consider this and make sure the benefits of treatment outweigh these risks. Sometimes blood thinning treatment is recommended to reduce this risk. Complications of lymphoma treatments such as dehydration and infection can also increase the risk of you developing a blood clot. 

Some patients require a line in their vein for treatments. A line is a tube which is inserted into one of your larger veins and can stay in place for months. Sometimes blood clots can develop in these lines. 

As well as lymphoma and its treatment you are more likely to have a VTE if you:

• are aged over 60
• are overweight
• smoke
• take the contraceptive pill or hormone replacement therapy (HRT)
• are pregnant, or have recently had a baby
• have had a blood clot in the past.

Most people with lymphoma will not develop a blood clot but having one can be serious, so it is important to know the signs and symptoms, and what to do if you think you may have one.

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What is a deep vein thrombosis (DVT)?

Veins carry blood back to your heart from the rest of your body. Superficial veins are close to the skin and are often visible. Deep veins are bigger, and they run through muscles and along bones.  A DVT is where a blood clot forms in one of these deep veins and is the most common type of VTE. 

What are the symptoms of a DVT?

In most cases a DVT will only affect one limb at a time which is usually a leg but can occasionally be an arm, or your tummy. The symptoms can include:

• throbbing pain usually in the calf or thigh
• warm red skin where the pain is
• one limb more swollen than the other
• swollen veins that are hard or sore to the touch.

What should I do if I think I have a DVT?

Having a blood clot can be very serious and needs to be treated quickly. If you think you might have a blood clot, seek medical advice straight away.

If you have any of the symptoms of a DVT then speak to your GP surgery and ask for an urgent appointment, or ring 111. If you also have chest pain or shortness of breath, then the clot may have travelled to your lung. This is an emergency so call 999 or get a friend or family member to take you to A&E straight away. 

How is a DVT diagnosed?

If it is suspected that you have a DVT you will be referred for an ultrasound scan. This should be within 24 hours. An ultrasound is like the scan used on pregnant women and will see whether blood is flowing normally through your veins. In some cases, for example if the ultrasound was not conclusive, you may also have an X-ray or CT scan of the vein. This is called a venogram. Dye is injected into your veins, and the X-ray or CT scan will show where the blockage is.

How is a DVT treated?

If you are unable to have an ultrasound quickly, whilst waiting you might have an injection of the blood thinning (anticoagulant) medication heparin or a tablet blood thinner. This will be decided by your medical team.

If a DVT is diagnosed the main treatment used is the blood thinning medication rivaroxaban. If the clot has caused a large blockage, then a procedure might be needed to remove the blood clot from the vein. Very rarely people are not able to have blood thinning medication. In these cases, a small filter is inserted into the vein to reduce the risk of the blood clot travelling to the lungs.

After you have started treatment, you will also be advised to not take any long journeys until at least 2 weeks after you start treatment. You should also keep mobile and if the clot is in your leg, you should try to keep it elevated whilst sitting down. This will help reduce swelling and help your recovery. 

Blood thinning medications increase the time it takes your blood to clot and so can cause excessive bleeding. Your medical team will go through this and the other side effects, and what to do if you develop them.

What are the possible complications of a DVT?

The most serious complication of a DVT occurs when a blood clot travels to the lungs which is called a pulmonary embolism (PE). 

After having a DVT you can also develop long term pain and swelling of the affected limb. This is called post-thrombotic syndrome and can be treated with compression stockings, exercise and painkillers.

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What is a pulmonary embolism (PE)?

A pulmonary embolism (PE) is where a piece of a blood clot breaks off, travels around your body and blocks one of the blood vessels in your lungs. It can be life threatening.

What are the symptoms of a PE?

These can occur with or without the symptoms of a DVT and include:

• sudden onset of unexplained breathlessness
• sharp chest pain, especially when you breathe in which can be in the front or back
• coughing up blood (haemoptysis).

What should I do if I think I have a PE?

Having a blood clot can be very serious and needs to be treated quickly. If you think you may have a blood clot, seek medical help right away.

If you have the symptoms of a PE, it is important that you are seen immediately as it can be life-threatening. Ask for an urgent GP appointment or contact NHS 111. However if you have severe difficulty in breathing, have chest pain, feel your heart is beating fast or pass out, call 999 or ask someone to take you to A&E immediately.

How is a PE treated?

If it is suspected that you have a PE, you will likely be admitted to hospital for further tests and treatment. This might be a blood test or a special scan called a computed tomography pulmonary angiogram (CTPA). You will usually be given an injection of a blood thinner before you get any test results. If tests confirm that you do have a PE, you will then continue on blood thinning medication. Depending on the type of blood thinning medication used you may require 5 days of blood thinning injections first, or a short period of higher dose tablet medication before you start a regular dose. You will then need to take anticoagulant tablets for at least 3 months. This can be as long as 12 months depending on the cause and your medical history. Anticoagulants stop the blood clot from getting any bigger and preventing any new ones from forming.  

Blood thinning medications increase the time it takes your blood to clot and so can cause excessive bleeding. Your medical team will go through this and the other side effects, and what to do if you develop them.

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How can I reduce my chances of having a DVT or PE?

Even though having lymphoma increases your risk of developing a blood clot there are many things that you can do to try and reduce this.

Healthy lifestyle

There are lots of simple day-to-day things which include to:

• stop smoking
• maintain a healthy weight
• stay active – even just taking short regular walks can help
• reduce alcohol intake
• drink plenty of water to keep hydrated, at least 6-8 glasses as recommended by the NHS.

Take care when travelling

If you go on a long journey, especially of more than three hours, whether that be by car, train or plane, your risk of developing a clot increases. Things you can do to reduce this risk include:

• wearing loose clothing
• drinking plenty of water to keep hydrated
• avoiding drinking alcohol whilst travelling
• making sure you move and stretch your feet regularly
• wearing flight socks
• getting up and moving around whenever possible.

Reducing risk when receiving treatment

When having treatment, especially in hospital, your risk of developing a clot can increase. Your medical team should assess this risk and then reduce it using a number of different methods: 

• Helping you to keep moving as much as possible.
• Prescribing compression stockings, which are tight above-the-knee socks.
• Keeping you well hydrated.
• You might be prescribed medication to thin your blood, especially if you are less mobile than normal.
• You might be advised to use a pneumatic compression device. This is worn around your legs and feet and regularly inflates to keep your blood flowing.

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