Go with the flow

Deep vein thrombosis (DVT) can be a worry for frequent travellers. It occurs when altered blood flow leads to the formation of a blood clot in a deep vein of the leg. Symptoms include a swollen or painful calf or thigh. In uncommon cases, part of the clot moves to the lungs, causing a pulmonary embolism (blocked blood vessel) that, if severe, may cause the affected lung to collapse.

DVT isn’t caused only by travelling. Each year, it occurs in between one and three people per 1,000, according to the Department of Health, and, of those, only one in 100 cases is fatal. Nevertheless, frequent travellers may be more at risk than others. Professor Mark Whiteley, a consultant venous surgeon and phlebologist, explains why: “The things that cause clots are the Virchow’s Triad [named after German physician Rudolf Virchow]. These are changes in the blood, changes in the blood flow and changes in the vessel wall. Any one of those can cause a clot.

“When you fly, you have a change in the flow, since you’re just sitting there, so the blood isn’t flowing as it should. You’re up in the air, so you have decreased oxygen and have changed the consistency