Avoiding Blood Clotting Complications When Flying Long Distances Before Surgery

An interview with Anne R. Bass, MD

  1. Introduction
  2. Clotting Complications: Deep Vein Thrombosis (DVT) and Pulmonary Embolism
  3. Long-Distance Travel and How it Relates to Clotting and DVT
  4. Blood Clotting Prevention on Long Flights
  5. Anticoagulants
  6. Surgery and Clotting Complications
  7. Risks of Clotting After Surgery
  8. Solutions for DVT


Patients travel from remote locations around the globe to Hospital for Special Surgery to be seen by our orthopedic specialists. Before receiving world-class care at the hospital, patients who travel by air in excess of 6-8 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.

Clotting Complications: Deep Vein Thrombosis (DVT) and Pulmonary Embolism

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.

According to Dr. Anne Bass, chairperson of the Deep Venous Thrombosis Prevention Committee at HSS, “DVTs can cause leg pain and swelling. Clots can also travel to the lung, causing a pulmonary embolism, which is a blockage of arteries that traverse the lung. 

“When left untreated, DVTs can inflict damage on the vein where the clot is located, causing chronic swelling and even ulceration," she explains. "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.”

Long-Distance Travel and How it Relates to Clotting and DVT

Although it is very rare for a patient to develop DVT from a long flight, Dr. Bass explains that the following 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.

Blood Clotting Prevention on Long Flights

To combat poor circulation on long flights, Dr. Bass recommends:

  1. Standing, stretching, and walking up and down the aisle as frequently as possible to get the blood moving and to "get the kinks out."
  2. 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.
  3. Prevention of dehydration on flights is as easy as drinking a steady amount of water or other non-alcoholic beverages.


Anticoagulants would seem to be a simple solution to blood clotting, but when taken preoperatively, they can thin the blood and increase the risk of bleeding at surgery.

Dr. Bass explains that anticoagulants should only be given to patients who are known to be at high risk for clotting (DVT, or pulmonary embolisms), either based on their medical history or their having a known genetic risk factor for clotting. Although Lovenox or heparin injections - and their effects - can wear off before surgery, the risk/benefit ratio of giving these injections to patients without an established elevated clotting risk is too high.

If a patient has a history of clotting risk, DVT, or pulmonary embolism in him/herself or his/her family, the patient should talk to a doctor in their own country as well as to their HSS doctor about treatment options before traveling to HSS for their surgical procedure.

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.”

Surgery and Clotting Complications

A very long flight prior to surgery can increase the probability of complications for patients undergoing hip and knee replacements when preventive measures are neglected.

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.

Risks of Clotting After Surgery

There is a risk of clotting for up to 4-6 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. The risk of bleeding after surgery diminishes with time, and one option is the use of warfarin (Coumadin®) which develops its blood thinning effect over several days.

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 3 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


Headshot of Anne R. Bass, MD
Anne R. Bass, MD
Program Director, Rheumatology Fellowship Program, Hospital for Special Surgery
Attending Physician, Hospital for Special Surgery

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