Understanding Deep Vein Thrombosis and Flying: Risks and Precautions

Posted 23 Oct

We call it deep vein thrombosis (DVT); you may have heard it called a “blood clot in the leg”. Either way, DVTs are one of those things that are incredibly important to know about so you can learn the signs and understand your risks, given that developing a blood clot can have some severe consequences. And if you’re a jet setter (or even a long commuter), then you definitely need to know about deep vein thrombosis. Here’s the lowdown from our podiatrists.

Deep Vein Thrombosis and Flying

A DVT describes a blood clot that forms in the deep veins, usually in the calves or thighs. Other areas of the body with a ‘deep vein’ can also get a DVT, such as in the pelvis, arms, abdomen, or even the chest, but these occur much less frequently. 

DVTs (blood clots) are a concern during flights because sitting still for long periods—often in cramped seats—slows down blood flow in the legs. A lack of movement greatly increases the chances of a clot forming, which is why doing long drives in a car (greater than four hours) also carries similar risks. 

If that blood clot breaks loose, it can travel through the bloodstream to the lungs, causing a blockage called a pulmonary embolism, which can be life-threatening. Long flights, with extended sitting times and reduced mobility, make DVT a real risk.

To better understand the likelihood and effects of a DVT, according to the research, there’s approximately one case of DVT per 1000 people, which makes it relatively common for something that can have quite serious consequences. It’s also the underlying source of 90% of acute pulmonary embolisms, which cause 100,000 deaths per year in the United States. 

In terms that are closer to home, approximately 30,000 Australians have a DVT each year. Blood clots are also responsible for an estimated 10% of all deaths in Australia, and yet up to 70% of these are preventable.

Is It Safe To Fly With Deep Vein Thrombosis? 

If you have an active deep vein thrombosis? No, that generally is not considered safe unless you’re cleared by a doctor. The limited movement and prolonged sitting during a flight means that your risk of blood clots growing larger or breaking loose, potentially leading to a pulmonary embolism like we described earlier. If you have a DVT and need to travel, you’ll definitely need to speak with your doctor and vascular specialist about how to best keep you safe and minimise your risks.

If you’re at risk of a DVT? Then flying can still be safe, but your doctor will likely advise you to take several precautions. It'll be more important to drink plenty of water, move your legs regularly, avoid alcohol, and take short walks during the flight to promote blood circulation. Your doctor may also recommend compression stockings for you (we do!) to reduce swelling and improve blood flow. 

Just to be clear, if you have a DVT or have any concerns about blood clots, you need to speak with your doctor or vascular specialist.

Who Is Most At Risk Of A DVT When Flying?

Here’s a comprehensive list of risk factors from a medical journal published last year - we’ve made it easy to understand if you have an increased risk of a DVT:

Risk factor: Reduced blood flow

• Staying still for long periods (such as bed rest, surgery, stroke recovery, or long flights) reduces blood flow, increasing the risk of clot formation.
  
• Situations that compress veins or slow blood flow, like pregnancy, tumours, vein narrowing, or congenital issues, can cause higher pressure in the veins, leading to clotting.
  

Risk factors: Injury to the vein

• Physical injury or surgeries can damage veins, making clots more likely.
  
• Venous catheters, intravenous drug use, or previous DVTs can also harm vein walls, triggering clot formation.
  

Risk factor: Increased blood thickness

• Diseases that increase blood cell counts (or even dehydration) make the blood thicker and more prone to clotting.
  

Risk factor: Higher risk of clotting (coagulation)

• Both genetic deficiencies (like deficiencies in specific proteins) and conditions like cancer, infections (sepsis), heart diseases, lupus, inflammatory bowel disease and many others can increase the risk of DVT.
  

Other risk factors:

• Certain variations in vein anatomy can naturally increase the risk of developing clots.
  
• Obesity (due to both slower blood flow and higher levels of a protein that makes blood more likely to clot)
  
• Ageing (especially over 60)
  
• Pregnancy
  
• Having surgery
  
• Admission to intensive care
  
• Dehydration
  
• Having a lower limb injury that limits your mobility for more than 72 hours
  

What Are The Signs And Symptoms Of DVT? Can You See A Blood Clot?

The most common signs and symptoms include swelling, pain, and changes in skin colour or temperature in the affected leg. Swelling is often one of the first noticeable signs and usually occurs in one leg, most frequently in the calf or thigh. This swelling can appear suddenly and worsen over time. The leg may feel tight, and clothes or shoes might fit more snugly than usual.

If pain is present, it’ll range from a dull ache to sharp, intense discomfort. It often starts in the calf and may feel like muscle cramping or soreness. This pain may be more noticeable when standing, walking, or applying pressure to the area. Tenderness is also typical, especially in the calf or inner thigh. Touching the area may cause discomfort or a heightened sense of pain.

In addition to swelling and pain, you might notice skin changes over the affected area. The skin may appear red, bluish, or darker than the surrounding area, and the affected leg may feel warm.

In some cases, veins near the skin's surface can become more visible or appear swollen. These symptoms can develop gradually or suddenly, so you’ll want to get help quickly if you notice these signs.

How Can You Prevent A DVT And Blood Clots During Air Travel?

To prevent DVT during flights, focus on keeping your blood circulation active throughout the journey:

• Aim to stand up, stretch, and walk around the cabin every hour. If standing isn’t possible, perform simple seated exercises, like ankle circles, heel raises, and foot pumps, to keep the blood flowing in your legs and help prevent blood clots.
  
• Wearing compression stockings helps encourage blood flow in the legs, reducing the risk of clot formation. They apply gentle pressure to your lower legs, preventing blood from pooling in your veins. They will likely be highly recommended if you have had recent surgery.
  
• Drink plenty of water throughout the flight to stay hydrated, as dehydration can thicken the blood and increase the risk of clots. Avoiding excessive alcohol and caffeine also helps, as they can contribute to dehydration.
  
• Choose comfortable, loose-fitting clothes that do not restrict blood flow, especially around your waist and legs.
  
• Crossing your legs for long periods can constrict blood vessels, so keep your legs uncrossed as much as possible.
  
• If you have a high risk of DVT, absolutely speak with your doctor before flying. They may recommend taking a blood-thinning medication before the flight to lower the risk of clotting. You may also be advised to avoid cramped seating and ask for exit row seating or an aisle seat instead.
  

What Should You Do If You Suspect DVT Mid-Flight?

If you suspect DVT mid-flight, it’s important to take immediate action to reduce the risk of complications, as it can be potentially life-threatening. Start by moving your legs and feet to promote blood circulation. While seated, perform gentle exercises such as ankle circles, heel raises, or foot pumps. This can help keep the blood flowing in your legs and potentially prevent the clot from worsening.

If possible, stand up and walk around the cabin periodically. Movement is key to promoting blood flow, which can alleviate some symptoms and reduce the risk of the clot growing larger. Keep drinking water, and alert the flight crew about your symptoms so they can provide support and be prepared for any emergencies. Once you land, get to a doctor quickly.

What Not To Do With Deep Vein Thrombosis? 

If you have a DVT, there are several things you should avoid to prevent complications:

• If you suspect you have DVT, don’t ignore symptoms like swelling, pain, or changes in skin colour. Prompt medical evaluation is critical to prevent the clot from worsening or causing a pulmonary embolism.
  
• Refrain from sitting or lying down for extended periods. Movement is key to promoting blood flow, so take short walks, stretch your legs, or perform seated leg exercises regularly.
  
• Massaging the leg where the clot is suspected or confirmed can potentially dislodge the clot, increasing the risk of it travelling to the lungs and causing a pulmonary embolism.
  
• Avoid tight clothing, especially around the legs and waist, as it can restrict blood flow and potentially worsen the condition.
  

If your doctor prescribes blood thinners or other medications, do not stop taking them without consulting your doctor. Stopping medication prematurely can increase the risk of the clot growing or new clots forming.

Final Thoughts On DVT

As podiatrists who have seen our fair share of DVTs and have chatted with patients who have been through the experience, the resounding message is that it’s always best to be safe. It’s much better to raise the alarm if you suspect a DVT and then get to breathe a big sigh of relief when you learn that everything is fine than shrug off a DVT to discover severe consequences for your health. Keeping educated on identifying a DVT and knowing how to reduce the risk of a blood clot is a fantastic first step.

Have questions or concerns about your lower limb health? Our podiatrists are here to help. We have two clinics across Brisbane CBD and Newmarket, and you can book an appointment by calling us on (07) 3356 3579 or booking online here.