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Traveller’s Thrombosis

 ... Prepared by Dr Cormac Carey - TMA member Toowoomba

Travellers Thrombosis or Deep Vein thrombosis (DVT) is a rare but dangerous medical problem which occurs when blood in the legs of travellers clots. The serious problems occur when the clot dislodges from the leg and moves to the heart or lungs where it interferes with their performance.

While it is several years since "Economy Class Syndrome" entered our travel jargon the recent release of newer and safer anti- clotting agents make it pertinent to reappraise our approach to this issue. In practical terms, risk factors need to be identified and their importance weighed against appropriate medical advice for each individual traveller.

Risk factors for travellers thrombosis

The following factors may increase an individual travellers' risk of suffering a thrombosis during travel:

  • Flights longer than 5 hours
  • Family history of abnormal clotting
  • Genetic clotting disorders
  • Recent lower limb surgery
  • Recent soft tissue injury of lower limbs
  • Pregnancy or shortly after delivery
  • Recent abdominal or pelvic surgery
  • Cancer
  • Female smokers who take the contraceptive pill

Persons with more than one risk factor are at even higher risk; E.G. Use of hormone replacement therapy in a woman, coupled with a genetic predisposition can lead to a thirteen times increased risk compared to the average traveller.

Perhaps the most important risk of all is having had a past episode of a Deep Vein Thrombosis with no recognised obvious trigger.

Some travellers have no particular risk factors. In that case, exercises as described on the aircraft instruction cards, plus plenty of water e.g. 200mls per hour are sensible precautions.

Low Risk Travellers

This would include persons over 40 years of age, overweight, or who have had recent minor surgery.
This group would be recommended to do as per low risk plus flight socks or grade 1 wear compression stockings
Note that persons with diabetes should seek medical advice before wearing any compression stockings.

Medium Risk Travellers

People aged over 50 years, previous DVT or pulmonary embolism (clot on lung), recent lower limb injury, treatment for heart failure, or women who have had a baby less than 6 weeks earlier.
Consideration should be given to booking an aisle seat, and wearing grade 2 compression stockings. Such stockings provide 20-30mmHg compression and only need to be knee high. They should be tried well in advance of the flight, as they can be difficult to put on when new.

High Risk Travellers

This category includes persons who have had DVT within the past twelve months, persons with a lower limb in a plaster cast or immobilizing splint, who have had a recent stroke or heart attack or major surgery within previous three months.
In addition to exercises, fluids, and aisle seat, consideration would usually be given to taking injections of low molecular weight heparin to lessen clotting during flight. Patients already on warfarin do not need heparin as well.

Persons who are hesitant to give themselves an injection prior to a flight, or who will have trouble carrying and storing injectible medication, will be happy to know there is now a medical breakthrough. There are new oral anti-clotting agents e.g. rivaroxaban. This is a prescription medicine that has been shown to prevent deep vein thrombosis in patients following hip and knee replacement surgery. Common dose for travel is one tablet daily, on the day before the flight, the day of the flight and the day after the flight.

Like all medications including the injectible heparin there is a potential for bleeding in the event of an injury, or a risk of interactions with other medications. The treating travel medicine doctor would consider these factors.


There is still no evidence that aspirin is helpful in preventing DVT as it affects the platelets and stops arterial clotting, but has very little effect on clotting in the veins. Users may experience side effects and be lulled into a false sense of security. If a person has significant risk, they should be on effective anticlotting medication as noted above.