Find out why they happen, who is at risk and what you can do to prevent them.
While blood clots are essential to stop us from bleeding to death from minor cuts, they can also be seriously bad news. Weight gain, an unhealthy diet, inactivity, smoking or even medication can cause blood vessels to become blocked, leading to major problems if left unchecked.
So how do blood clots form and who is at risk?
Not all blood clots are bad news
They form when blood turns from a liquid into a semi-solid mass. ‘Clotting is a natural process that “plugs” a hole and stops you losing too much blood in the event of an injury – on the outside, this is known as a scab,’ explains Professor Mark Whiteley, a leading consultant venous surgeon. But when platelets, plaque or cholesterol build up inside a vessel, it can create a clot, and can be life-threatening.
There are 3 main causes of blood clots
Blood does not normally clot inside our vessels, so something has to change in order for clots to appear. These include: Changes in blood composition, which include concentration levels of plasma, red blood cells, white blood cells and platelets; changes in blood flow if it becomes sluggish or slow; and changes in the vessel wall, where damage may be caused by lifestyle factors.
A staggering 60% of blood clots happen during or after a hospital stay, due to inactivity. But there are things you can do to prevent blood clots when you’re sedentary in hospital or on a long-haul flight. ‘In hospital, there are a number of blood tests to determine somebody’s risk of stroke, heart attack or pulmonary embolism,’ says Dr Emeka Okorocha. ‘You may be given blood-thinning tablets and surgical stockings to reduce the risk.’ When you are on a plane, moving your legs a lot, even when sitting, can help. Try extending your legs straight out and flexing your ankles, or pull each knee in towards your chest.
Smoker? It’s time to quit
‘Artery clots are usually caused by things that are bad for your circulation,’ says Professor Whiteley. Smoking is particularly bad, as it thickens blood and damages vessel walls. ‘The walls of our blood vessels are lined with a special sort of cell that prevents normal blood from clotting on it, but smoking changes the surface of these blood platelets, making it easier for them to stick together and form clots,’ he explains. Artery walls can also be damaged by high blood pressure, a high-fat diet and diabetes. But healthy lifestyle changes can reduce your risk of getting blood clots.
Hydration is important
Preventing a blood clot could be as simple as drinking a glass of water. ‘When people are dehydrated, the composition of their blood changes and becomes more concentrated,’ says Professor Whiteley. Drinking plenty of water helps to thin the blood and keep it flowing. Loma Linda University researchers found that people who drank five or more 250 ml glasses of water daily cut their stroke risk by around 53%.
Symptoms can vary – here’s what to look for
Spotting signs early could save your life. If you notice any of these symptoms, seek urgent medical help:
- Sudden shortness of breath and chest pain, particularly when you breathe in ✣ Coughing up blood
- Painful, swollen legs
- A tender calf, particularly when standing
- A red patch on your leg that feels warm to the touch
- Sudden and severe headaches
- Numbness or weakness, particularly on one side of your body
Different clots = different symptoms
A blood clot in an artery can be serious, and can cause a heart attack or a stroke. They usually cause sudden and severe pain and, in the case of stroke, can be accompanied by limb weakness, as well as difficulty in speaking and seeing. Don’t worry, there are simple lifestyle changes that you can make to keep healthy and to significantly reduce your risk.
DEEP VEIN OF THE LEG
A blood clot in a deep vein of the leg (called deep-vein thrombosis or DVT) causes a swollen leg and pain. There is a risk that some of the clot could break off and travel all the way to your lungs – causing a pulmonary embolism – but there are simple ways to reduce your risk.
SUPERFICIAL VEINS OF THE LEG
A blood clot that occurs in the superficial veins of the leg causes superficial venous thrombosis (called phlebitis). This is usually just painful, but if the clot extends near the deep vein, it could travel to your lungs too, so it’s good to get these checked out.
Prevention is key
- Keep at a healthy weight (BMI 19–25)
- Maintain healthy blood pressure and cholesterol
- Reduce your salt and sugar intake
- Stay hydrated
- Keep moving and wear compression socks during a long flight
- Elevate your feet and legs while sitting or lying down to stop blood pooling
- Don’t smoke
- Speak to your GP if you have a family history and are taking oral contraceptives
Beware of varicose veins
When veins bulge or become twisted, it leads to varicose veins. This happens when a valve in the vein fails and blood collects in the vessel, rather than continuing towards the heart. Blood flow becomes slow, which in some cases can cause superficial blood clots – these usually clear by themselves and don’t lead to DVT. ‘Often the only bother is looking unsightly, but research suggests that for one in 20 people, “simple” varicose veins will deteriorate every year, leading to swollen ankles, eczema or brown stains around the ankles,’ says Professor Whiteley. If your varicose veins are causing you discomfort, pain, swelling, pigmentation, or an ulcer has lasted more than two weeks, go see your doctor.
Seek medical help!
All types of clots should get checked out. Even blood clots in ‘superficial’ veins should be assessed by a specialist, who will perform an ultrasound to monitor blood flow. ‘Anyone who has a clot close to the deep veins must have anticoagulation treatment (drugs to thin the blood) to stop the clot from travelling to their lungs.’
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