Some people are very frightened of getting Deep vein thrombosis (DVT) whilst flying. Thousands and thousands of people fly each year. The cases of Deep vein thrombosis (DVT) are tiny but if you take some very simple precautions you can reduce that tiny risk.

What is deep vein thrombosis?

Deep vein thrombosis (DVT) is the formation of blood clots in major deep veins, commonly in the thigh or calf. Deep vein thrombosis has been linked to long distance travel. Some call it 'economy class syndrome'.

It is not only long distance air travel that puts people at risk. Sitting in one position for too long is a major factor. It can arise in first and business class not just economy, during a long car, bus or train journeys. If you work at a computer desk, or by a cash desk for long hours you are also at risk. Prolonged inactivity is the real problem.

What causes deep vein thrombosis (DVT)?

Blood clots are formed when blood stops moving and coagulates. Blood coagulates when blood clots outside a blood vessel, this is a normal process which protects the body against losing blood following minor accidents and cuts.

If the blood clots inside a blood vessel however (as with DVT), this can be dangerous. Just imagine thick lumps flying around your blood stream entering vital organs. That is what you want to avoid.

Most of us have experienced our legs and ankles feeling tight after flying. That is the normal swelling brought on by being in a pressurised environment. The risk while flying is increased because of the reduced cabin pressure at high altitudes, which causes fluid to pass from the blood vessels into the surrounding tissue, causing thickening of the blood.

Normal movement of the calf muscle when walking helps to pump blood from the legs to the heart, but with the loss of fluid while sitting for long periods, the blood can thicken, coagulate and form a clot in the deep veins of the leg.

In most cases of Deep vein thrombosis DVT, the clots are small and do not cause any symptoms. The body is able to gradually break down the clot and there are no long-term effects. The danger with larger clots may partially or totally block the blood flow in the vein and cause swelling of the calf (this is usually different from the mild ankle swelling that many people get during long haul flights) pain in the calf that is noticeable, or worse when standing or walking.

The following increases your risk of Deep vein thrombosis DVT, blood clotting disorders, varicose veins, cancer, heart failure, pregnancy, use of estrogen-containing medications, recent surgery or trauma, smoking, being overweight, age over 40 years and prolonged immobility.

Deep vein thrombosis prevention tips

There are a number of simple steps you can take to help prevent Deep vein thrombosis DVT. Walk down the aircraft aisles regularly, or if travelling by car, stop frequently, get out and take a walk. Do ankle and knee exercises every half hour while seated and wriggle your toes frequently.

 Make sure you dink plenty of water and go easy on caffeine and booze. If advised by your doctor take aspirin. Wear knee-high compression stockings can help.

Compression stockings are favoured by many long distance travellers to reduce the risk of blood clots. Wearing a compression stocking counteracts the loss of fluid into the tissue of the leg, and so reduces the risk of clotting.

Some doctors are now routinely recommending these stockings to people over the age of 40 who will be travelling for more than five hours. For specific advice consult your doctor.