Avoiding Blood Clotting Complications When Flying Before and After Surgery

Many people travel from around the globe to Hospital for Special Surgery to be seen by our orthopedic specialists.

Passengers boarding a commercial airliner.

Before receiving world-class care at the hospital, patients who travel by air in excess of six to eight hours should be sure to take necessary precautions to avoid blood-clotting complications such as deep vein thrombosis (DVT) and pulmonary embolism.

Using simple preventive measures, patients can maximize their resistance to blood clotting and increase their likelihood of surgical success.

What is a deep vein thrombosis (DVT)?

Deep vein thrombosis (DVT) is a blood clot, commonly found in the leg or thigh, that can form as a result of stagnant blood flow, coagulation, and damage to vein walls. DVTs can cause leg pain and swelling.

What is a pulmonary embolism?

A pulmonary embolism is a blockage of arteries that traverse the lung Blood clots such as a DVT can travel to the lung and lead to a pulmonary embolism.

“When left untreated, DVTs can inflict damage on the vein where the clot is located, causing chronic swelling and even ulceration," explains Anne Bass, MD Attending Physician in the Division of Rheumatology at HSS. "Pulmonary emboli can produce symptoms of shortness of breath, chest pains, a rapid heart rate, or fainting. In very rare cases, a fatal blockage of pulmonary arteries may occur.”

How does flying relate to blood clots and deep vein thrombosis?

Although it is very rare for a person to develop a DVT from a long flight, airline passengers are sedentary with their legs bent for extended periods of time and tend to become somewhat dehydrated during flight. Each of these factors may contribute to blood clot formation.

  • When flying, passengers are normally sedentary and immobilized. This is a problem because it is the contraction of muscles in the legs, normally caused by motion and movement, that allows blood to circulate back to the heart. When the body is immobilized, blood pools in the legs, and this increases the risk of clotting. Additionally, when seated for a lengthy amount of time, the knees remain at a right angle, resulting in a “kink” in the veins of the legs, preventing proper circulation.
  • The dryness of the recirculated air on planes can leave its passengers dehydrated. This leads to the blood to become concentrated and more prone to clotting without the proper amount of hydrating fluids.

How can you prevent blood clotting on long flights?

To combat poor circulation on long flights, try to stand up and stretch during the flight, and stay hydrated by drinking water or other nonalcoholic beverages. Wearing compression socks may also help.

  • Standing, stretching, and walking up and down the aisle as frequently as possible to get the blood moving and to "get the kinks out."
  • In addition to exercising, graduated compression stockings are also recommended to help prevent blood pooling in the legs. They can be found at surgical supply stores and pharmacies.
  • Prevention of dehydration on flights is as easy as drinking a steady amount of water or other non-alcoholic beverages.

Can taking anticoagulants prevent a DVT during surgery?

Anticoagulants would seem to be a simple solution to blood clotting, but when taken prior to surgery, they can thin the blood and increase the risk of bleeding at surgery. Anticoagulants should only be given to patients who are known to be at high risk for blood clots, either based on their medical history or their having a known genetic risk factor for clotting.

Although anticoagulant pills or injections − and their effects − can wear off before surgery, the risk/benefit ratio of giving these medications to patients without an established elevated clotting risk is too high.

If a person travelling to HSS from outside the United States has a history of clotting risk, DVT, or pulmonary embolism (or someone in their family does), they should talk to a physician in their own country as well as to their HSS doctor about treatment options before traveling to HSS for their surgery.

A history of clotting and its resulting complications does not prohibit patients from traveling by air, however, Dr. Bass notes “Even those with an elevated risk of clotting complications will be able to travel to HSS as long as preventive measures are taken,” she says.

Does flying before surgery increase the risk of clotting complications?

If preventive measures are neglected, a very long flight prior to surgery can increase the probability of complications for patients who undergo orthopedic surgeries such as a hip or knee replacement.

In orthopedic surgery, the cutting of bones prompts the body to respond by revving up its clotting system, a response that mirrors its reaction to a bodily injury. Due to the size of the bones involved in hip and knee replacements, there is a higher risk of blood clotting than other orthopedic surgeries. Dr. Bass also adds that in patients with hip fracture, the risk is further increased because of the immobilization of patients prior to surgery.

What are the risks of blood clots after surgery?

There is a general risk of clotting for up to four to six weeks after surgery for all patients, but flying long distances aggravates this problem further. As a result, those who travel such distances may be subject to enhanced preventive measures after their procedure.

For example, after hip and knee surgeries, blood thinners are typically administered to patients. If there is a long plane flight in the patient’s future, their doctor will choose an appropriate type of blood thinner to accommodate those plans. Patients can be given anticoagulants following surgery, and the choice of blood thinner includes balancing the risk of clotting with the risk of bleeding after surgery.

Solutions for DVT

When DVT is detected in patients, they are treated with blood thinners, including heparin injection, twice a day. These work quickly to help dissolve the blood clot and prevent the formation of new clot. Simultaneously, the doctor will initiate an oral blood thinner like warfarin (Coumadin®), which is continued for three months if a clot is found in the leg, and six months if the clot is in the lung.

Although there are solutions to dealing with DVT, especially when discovered early, effective prevention is always a good policy.

Summary by Mike Elvin


Anne R. Bass, MD
Attending Physician, Hospital for Special Surgery
Professor of Clinical Medicine, Weill Cornell Medical College

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