Are YOU at risk of a blood clot? From jet-setting to taking the Pill: Leading vascular surgeon explains the 9 top risk factors - and how to beat them
- Every five minutes, someone dies of a blood clot or deep vein thrombosis
- Blood clots can cause heart attack, stroke, gangrene, dead leg, or a dead gut
- However simple changes in lifestyle can dramatically lower your risk
- Surgeon Mark Whiteley explains what causes clots and how to prevent them
Thrombosis is a common condition caused by blood clots forming in an artery or a vein - costing the UK £640 million annually and up to $39.5 billion in the US.
Indeed it's been estimated that every five minutes someone dies of a blood clot or deep vein thrombosis (DVT).
Yesterday, we reported the story of Sarah Cobb , 27, who died of a fatal blood clot allegedly caused by the contraceptive pill.
This is an issue that comes up from time to time, causing confusion no doubt among the over 14 million women in the UK and US who take it.
But what exactly is it and how can it be treated and avoided? Here, vascular surgeon Professor Mark Whiteley explains.
Thrombosis is a common condition caused by blood clots forming in an artery or a vein. It's estimated that every five minutes someone dies of a blood clot
The fact that the blood clots is a good thing. In fact we wouldn't survive long if our blood didn't clot.
If blood did not clot, we would be continually bleeding. Not only during the obvious times, such as when we fall over and cut ourselves, but also from lots of little bleeding points such as in our bowel, bladder, mouth, etc.
We are constantly springing little leaks but, thanks to our clotting system, they are plugged before we even know about them.
When a blood clot forms in the heart or an artery it can cause conditions such as a heart attack, stroke, gangrene, dead leg or a dead gut, although this is not common.
The major risk factors are smoking, high blood pressure, diabetes and high cholesterol levels. On top of this are some factors we can't influence such as old age and being male.
However, more common than this is venous thrombosis. Blood clots are much more likely to occur in the veins because veins are much bigger and have a slower flow of blood.
Signs and symptoms
About 50 percent of people suffering from DVT won't even know that they have it. However, if you are showing signs, you may have:
- Generalized pain in the leg, usually the calf, and some swelling if the blood clot is particularly big
- Discomfort when walking, particularly in the calf muscle
- A tender lower leg and swelling
- If the clots are in the upper thigh or even pelvis, the leg is often very swollen, very blue and very tender.
Superficial venous thrombosis (also called phlebitis) occurs in the superficial veins and so the clots are closer to your skin and rarely include swelling. Symptoms may include:
- Tender lumps palpable under the skin
- They often feel like 'tubes' or lumps
- Red and inflamed skin
- Inflammation around the affected area
Here are the most common causes of venous thrombosis:
1. SMOKING
Smoking causes 'hardening of the arteries'. Although nothing is visible to the naked eye, research has shown that the vein wall in smokers is very inflamed and damaged.
People who smoke have much thicker blood. Certain proteins, particularly fibrinogen, increase in smokers making the blood thicker, but as the lung tissue gets damaged, the body reacts by producing more red blood cells and this also thickens the blood.
The vein wall in smokers is very inflamed and damaged which increases the risk of blood clots
The thickening of the blood and inflammation of the vein wall both increase the risk of blood clots and venous thrombosis.
What does this mean for me?
In short, if you smoke – find a way to stop.
2. ORAL CONTRACEPTIVE PILL
When the first oral contraceptive pills were produced in the 1960s, they had a very high-dose estrogen content, which made DVT and superficial venous thrombosis much more common. This was because the estrogen changed the composition of the blood and made it much more likely to clot.
What does this mean for me?
Over the last couple of decades, combined pills with estrogen and progesterone compounds have reduced the dose of estrogen considerably, and the 'mini pill' has no estrogen in it at all.
The result of this is that the oral contraceptive pill does slightly increase the risk of DVT and superficial venous thrombosis, but by itself, is only a small risk factor nowadays.
Oral contraceptive pills slightly increase the risk of blood clots due the dose of estrogen
However this is completely changed if the person on the oral contraceptive pill has another risk factor which can then magnify the effect of the pill. The most important ones are smoking and being on the pill, which gives a much higher risk of thrombosis compared to the normal person.
Other factors that could worsen the risk of someone on the pill include having major surgery, major illness or a family history of venous thrombosis. Women taking the oral contraceptive pill who smoke should seriously consider stopping smoking as soon as possible.
3. VARICOSE VEINS AND 'HIDDEN VARICOSE VEINS'
For decades, doctors and nurses thought that varicose veins were 'only cosmetic'.
If you see bulging veins on the surface of your skin, they are varicose veins. They actually occur because the underlying veins have lost their valves and are allowing blood to fall backwards down the veins, stretching the veins below them.
Blood falling the wrong way down the veins causes inflammation around the ankles and damages the vein wall – and this can cause all sorts of problems including blood clots, bleeding, venous eczema, skin damage and even venous leg ulcers.
However, in many cases, this will not also present bulging veins on the surface, and instead are 'hidden varicose veins'.
Varicose veins cause inflammation because of blood falling the wrong way down the veins
Many medical professionals will tell you that if you get a clot in varicose veins, it is called 'phlebitis' and does not cause any problem apart from a painful lump. Until 2012, this was widely thought to be correct.
However, two major committees produced guidelines to the contrary after research had shown that clots in the superficial veins could extend into the deep veins and then fly off to the lung – a condition called pulmonary embolism or PE (an embolism of the clot in the leg veins travelling up through the veins, through the right heart and into the lungs).
What does this mean for me?
Since 2012, the guidelines state that people with 'phlebitis' (or more correctly superficial venous thrombosis) should be referred to a vein clinic or a vascular service for a venous duplex ultrasound scan to check whether the clot is near the deep veins.
If it is, the patient needs to have anticoagulation to reduce the risk of a pulmonary embolism. However, virtually nobody today gets referred for such a scan and most only receive painkillers and support stockings.
Incredibly, some even get given antibiotics even though there is no infection involved.
4. OPERATIONS
Having surgery is a well-recognized cause of DVT. This is particularly common if the surgery is of the abdomen or of a major joint such as the hip replacement.
This is due to a number of contributing factors, such as the fact that patients are usually starved for a minimum of six hours before the operation, are usually quite dehydrated and lie still for a long period of time due to general anesthetic.
The operation itself can have an impact on the major veins – either by direct pressure being placed on the major veins, such as in abdominal surgery, or twisting the veins in the legs during manipulation, as in hip surgery.
Operations can have an impact on the major veins either by direct pressure or twisting them
What does this mean for me?
We have now changed to performing local anesthetic walk-in, walk-out surgery as much as possible which decreases the risk of blood clotting. As technology continues to advance, increasing numbers and types of procedures will be treated in a minimally invasive way.
5. LONG-DISTANCE FLYING
The risks of getting DVT from flying hit the headlines about 15 to 17 years ago when a young lady flying from Australia to the UK died after the flight.
Getting DVT from flying was labeled 'economy class syndrome' as it was instantly thought that it was the lack of movement in airline seats which caused the change in blood flow.
Research over the years has pointed out that when aircrafts fly at commercial levels, the passenger cabins are pressurized to keep the atmosphere reasonable.
However, to save fuel and to keep the planes as light as possible, cabins are pressurized to somewhere around 7000 feet altitude pressure – not the full atmospheric pressure that you are used to the ground.
This means that the air is 'thinner'. Scientifically, although the percentage of oxygen in the air is the same as at ground level (approximately 21 percent), the actual molecules are further apart due to the lower pressure.
So there is less oxygen in any set volume of air and hence, each breath has got less oxygen in it than a breath at ground level. This means that the level of oxygen in the blood is decreased at altitude.
During flights under four hours this seems to have very little effect, except for people who have heart or respiratory disease.
Long-distance flying puts people at risk due to the decreased level of oxygen in the blood
However for long flights, the low oxygen levels in the blood mean that the cells on the inside of the vein walls start undergoing a stress reaction.
Rather than being perfectly flat, they start bulging a little in the middle, getting a bit lumpy and pulling apart from the cells around them.
This allows water to leak out of the blood through the vein wall and into the tissues causing swelling of the ankles.
Finally, it is likely that activity is reduced and so there is less blood pumping into your veins than there would be if you were walking around normally. This change in the blood flow can also cause clots.
A recent study has suggested that up to one in 12 people can show minor DVT after a flight of seven hours or more. Obviously most of these people do not have any obvious clinical symptoms of DVT, but the fact this can be seen shows that the problem is real.
What does this mean for me?
The best ways to avoid DVT in commercial flights is to consider the following: reduce the changes in your blood constituents by keeping hydrated.
If you drink caffeine or alcohol (both of which dehydrate you) make sure you also drink plenty of water or juice to rehydrate.
There is precious little that can be done to reduce changes to the wall itself. However, changes in the blood flow can be improved by wearing well fitted travel stockings as well as keeping your feet moving, either by wiggling them in your chair or walking up and down the aisle occasionally.
Properly fitted travel stockings reduces the amount of water that can escape from the veins into the tissue. They also narrow the veins, making the flow faster and clotting less likely.
But make sure they are properly fitted, rather than straight off the shelf or they might not have the same effect.
6. INACTIVITY
Inactivity is a major cause of DVT. Most people will naturally move, even when asleep, due to internal body reflexes, however when we concentrate for long periods of time we can overcome these and stay stationary allowing blood to pool and therefore clot.
This was the cause of death in a young man that was reported in the national press a few years ago who was playing video games for long periods of time without moving.
Of course this is also the cause of DVT in people who are unable to move normally due to general immobility, plaster casts on the legs, or who are unwell.
In patients who are unwell, they may have additional problems such as dehydration, or the presence of cancer which also increase the risk of thrombosis.
Being stationary for long periods of time allows the blood to pool and, therefore, clot
What does this mean for me?
The best way to prevent this is to exercise. This may be as simple as just getting up and walking around every half hour or so.
For those who are immobile, it is often sensible to have a thromboembolic disease compression stocking (TED stocking) or even a mechanical aid to pump the blood in the foot or lower leg, to keep blood flowing up the veins periodically.
For those at very high risk, injections of heparin or tablets that reduce blood clotting (anticoagulants) can also be used to reduce risk of DVT.
7. DEHYDRATION
Dehydration is a potent cause of DVT, as it clearly changes the constituents of the blood. Many people who are on holiday in very hot climates are particularly prone to dehydration.
This can be worsened if they play sport, fall asleep on the beach and therefore don't rehydrate or drink a lot of alcohol/caffeine, which will also increase dehydration and the concentration of the blood.
When you are on holiday, dehydration followed by a flight home, can be a common cause of DVT.
Dehydration is a potent cause of blood clots as it changes the constituents of the blood
Fever can also be a cause of dehydration. Even quite 'minor' ailments such as the flu or a severe cold, that raise the temperature for a day or two, can keep a person in bed, change their mobility and reduce their access to water.
If they have a temperature and are sweating a lot, they can also quickly become dehydrated.
What does this mean for me?
Any illness that causes excessive vomiting or diarrhea will also cause severe dehydration and if you are ill and unable to rehydrate by drinking fluid, may even need to be admitted to hospital to have fluid administered by a drip.
8. CANCER
Although doctors have known that cancer can increase the risk of DVT and superficial venous thrombosis for many years, it has not ever been regarded as a major cause of blood clots.
However, in recent years the National Institute of Health and Clinical Excellence has highlighted that any patient who suffers from DVT that occurs for no known reason, must be screened for a hidden cancer.
Indeed, it is estimated that if the patient is over 40 and has an unprovoked DVT thrombosis, there is a one in 10 chance that they have a malignancy.
Anyone who has an unexpected DVT, particularly if they are over 40, must be examined by a doctor to look for evidence of malignancy and simple screening tests should be performed to make sure there is no hidden cancer.
What does this mean for me?
Patients with established diagnosis of cancer should be monitored for any signs of DVT and, if at high risk, preventative measures such as injections to reduce blood clotting or a TED stocking should be recommended.
Mark Whitley recommends seeing a doctor for any family history of blood clots in the veins
9. FAMILY HISTORY
Last, but certainly not least, is a family history of blood clots in the veins. Some families have a terrible history of blood clots.
Clots in the arteries causing stokes, heart attacks, aneurysms or leg bypasses are arterial and do not count as far as this risk is concerned.
There are many proteins in the blood that are involved in the normal process of making or breaking down blood clots. In some families, a mutation occurs and the protein does not function normally.
What does this mean for me?
Although science is advancing all of the time, it must be pointed out that not everybody with a thrombophilia get a positive blood test.
Probably over half of the families that have obvious thrombophilia will actually have a negative blood test. It is not that the blood test is wrong, it is just that we do not know all of the factors that cause the condition..
Therefore, anyone who has a clear family history of thrombophilia will be treated on the family history regardless of whether the blood test is positive or negative.
Avoiding blood clots can come down to changing simple lifestyle habits including quitting smoking, managing blood pressure, exercising, and eating well.
Avoiding blood clots can come down to changing simple lifestyle habits including quitting smoking, managing blood pressure, exercising, and eating well
TREATMENT FOR BLOOD CLOTS
The best way to treat these is to avoid them in the first place. That is, do not smoke, keep an eye on your blood pressure, keep any diabetes under control, exercise well, and eat well to keep your cardiovascular system healthy and your weight normal and take statins if your cholesterol is high.
However, that's not always possible. If you do get an arterial thrombus or embolus, then treatment needs to be immediate, and depends very much on which part of the body is affected.
If the clot has gone to the brain or heart then the treatment is often injecting thrombolysis to break down the clot. If the clot has gone down the leg or arm, then surgery is often required to remove the clot.
This article was originally published by Healthista
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