Risk factors and Prevention of Travellers Blood Clots or Deep Vein Thrombosis (DVT)

Deep Vein Thrombosis (DVT) is also known as “Economy class syndrome”. This is a bad term as they can occur in first or business class, in buses, or in fact any prolonged travel over 4hrs. In fact, there is probably more leg movement in economy class as the seating is so uncomfortable! It is not known whether traveller’s clots differ from post-operative clots. Aisle seats have a lower incidence of DVT than window or middle seats. Short people, and tall people, also seem to have a higher incidence. Travel is not the only factor, as they can occur with prolonged squatting as with gardening. They also can occur after any surgery, although some operations are more of a concern than others. There are recognised risk factors (see below).

We are talking about blood clots that are in the veins deep inside the leg, and are known as Deep Vein Thrombosis (DVT). You can’t see these veins and so clots are diagnosed with a blood test, or an ultrasound. They are potentially lethal, as they can break off and travel along with the blood stream and lodge in the lungs. Most patients survive however.

Apart from DVT, the Superficial Veins Thrombosis (SVT, AKA superficial phlebitis) is a common condition caused by varicose veins or prolonged immobility (like long haul flights). The leading symptom of the disease is a formation of red, tender lumps in the place where varicose veins were, or superficial veins trunks are running (like inner side of the thigh or leg). For a long time, SVT has been treated as a minor problem. Recently we discovered, that about 20% of extended SVT can spread to deep veins causing DVT or even PE. That is why it is so important to prevent SVT from happening by treating existing varicose veins or using compression stockings when flying.

Varicose veins can be successfully treated in The Vein Centre 3 months after the onset of DVT, 6 weeks after extended SVT or 2 weeks after localised SVT.

Risk factors for DVT

  • Previous DVT
  • Recent surgery
  • Recent trauma to the leg such as in sports teams
  • Active cancer
  • Known hereditary clotting tendencies
  • Family history of DVT
  • Oral contraceptives
  • Prolonged squatting or travel >4hrs
  • Pregnancy
  • Obesity (BMI > 30)
  • Age over 40 yrs
  • Varicose Veins

The top 5 are regarded as higher risk


Walking, and compression knee length stockings are the only proven beneficial factors.

Abstaining from alcohol does not appear to help. Although unproven, drinking lots of fluids to prevent dehydration will help to minimise jet lag and makes sense.

Who should wear compression stockings? Those with more than one risk factor should definitely wear them. You only need knee high with an ankle pressure of 30mmHg. Aspirin  appears to have only a small benefit in preventing DVT. If you have one of the 5 high risk factors, you should come and have a consultation with us about the risks, and possibility of adding some anti-clotting medication. We can also advice you about the recommended compression stockings or assess you for a presence of superficial vein disease like varicose veins.

Treatment of an existing varicose veins also plays an important role in prevention of DVT or SVT.