When taking a long-haul flight, most of us are aware these days of the potential risk of deep vein thrombosis (DVT), and the importance of moving around every now and then to boost blood flow.
In the UK, around one in every 1,000 people are diagnosed with the condition each year. It can affect anybody but becomes more common with age. Obesity, pregnancy, smoking and periods of inactivity (such as being bed-ridden following illness or surgery) can increase the risk, along with the existence of other health conditions – including some cancers and heart disease. Taking certain medications, like some oral contraceptive pills, can also contribute.
Deep Vein Thrombosis (also known as DVT) is a blood clot that forms in the deep veins of the body, most commonly in the calf muscle of the leg. Sometimes there are no symptoms, and clots can be treated with anticoagulant medicines (drugs that reduce clotting).
There are some warning signs including pain, swelling, a heavy ache and redness/warmth of the skin in the affected area. Speedy treatment is crucial, as if it’s left untreated deep vein thrombosis can lead to a much more serious condition called a pulmonary embolism. This happens when a blood clot finds its way to the chest, blocking vital blood vessels in the lungs. A pulmonary embolism can be fatal, so it’s vital to seek medical help immediately if you’re concerned.
Thankfully, there’s a lot that can be done to prevent DVT, and having a history of the condition does not automatically mean flights are off the agenda, as Professor Mark Whiteley of The Whiteley Clinic one of the world’s leading venous experts, explains…
“Flying is definitely associated with deep vein thrombosis, and much research has been done on this subject,” says Professor Whiteley, who points out that it is flights over four hours that are linked with a “significant risk”.
“The two main known reasons are the inactivity due to sitting still for long periods of time, and secondly the fact that the air is thinner at altitude. This means there are less oxygen molecules in the air, and so there is less oxygen in the bloodstream. This can affect the lining of the vein walls, predisposing to a DVT.”
A deep vein thrombosis blood clot can develop anytime from a few days to a few weeks after a flight – usually after a long-haul journey. However, if you’re active during your flight and in the subsequent weeks, these blood clots can break up naturally.
Hopefully yes – but you’ll need to speak with your doctor, and possibly take extra precautions.
“This question is not simple to answer as it is dependent on a number of factors, such as how long ago the first DVT was, whether the person has experienced more than one DVT, the reasons the previous DVT occurred, its size, and so on,” explains Professor Whiteley. “However, as a general rule, as long as the patient takes advice from a specialist, they should be able to fly again, even if it does mean taking medication or an injection to keep safe during the flight.”
Whiteley also notes that a one-off, small DVT suffered many years ago is unlikely to indicate a significant increased risk. However, if you have had “one or two major DVTs” with causes that have not been investigated and you’ve not been prescribed anticoagulation medication, you might be advised not to fly until you’ve seen a specialist.
The British NHS guidelines for preventing future blood clot when flying are to wear flight socks or compression stockings, do plenty of exercises, walk around whenever you can, avoid alcohol and drink plenty of water.
While this varies hugely from person to person, if you are out of the recovery phase, taking anticoagulation medication (such as warfarin) and doing plenty of exercise, the risk of you developing DVT again is low and you should be able to fly as and when you please. This includes long-haul flights.
Your doctor will be able to advise you whether this will be a few weeks or a few months.
Not always but it might do – and this is why having the cause investigated is important. “It was previously thought that having one DVT will put you at risk forever. However, it’s now recognised that DVTs come in different shapes and sizes, and for different reasons,” explains Whiteley. “This is why it’s really important to not only receive the correct treatment, but also find out what the underlying cause was, so that future problems can be avoided.”
There are things you can do to lower the risk of DVT – and Professor Whiteley points out that these are things everybody can benefit from, not just those with a history or who are deemed ‘higher risk’.
“I would recommend keeping well hydrated, both in the lead up to and during a flight, and making sure you move around in the cabin every half-hour or so,” he suggests. “If your flight is longer than four hours, or if you have any predisposing medical conditions [which may put you at increased risk of DVT], I would also suggest wearing properly fitted grade-two graduated compression stockings, at least to the knee if not above.”
If you are able to take aspirin, you might want to consider taking 75mg before flying, though Whiteley notes that “whether this actually helps is unknown”.
If your DVT developed into a pulmonary embolism, you will likely be taking anticoagulants following your treatment. It’s essential that you seek the advice of your doctor if you are planning on flying anytime soon, but the actions you can take to avoid future pulmonary embolisms are to continue to take any prescribed anticoagulant medication, wear compression stockings, exercise regularly and drink plenty of water.
The other question PE sufferers ask is “how long do I have to wait to fly after my pulmonary embolism?” The answer is there is no rule of thumb for this – you might be more or less at risk based on your age, weight, fitness or family medical history.
More information on this can be found on the NHS page.
If you've had a thrombosis in the past, it's worth mentioning this to your travel insurer to ensure that you are covered in the event you develop another clot during your trip which causes the need for medical treatment.
You can compare quotes from a variety of specialist insurers on Medical Travel Compared.
Using our comparison tool, you will be able to declare your pre-existing medical conditions quickly and easily online and generate the most competitive quotes based on your condition(s). This facility is designed not only to help you find a sympathetic travel insurance provider but help you to avoid paying over the odds.