Summertime plans could include a 21-hour flight from the airport to the “Land Down Under,”It’s a short drive from Boston to Grandma in Phoenix. You can also take a train trip through the Grand Canyon for 10 hours or travel across country by bus to Orlando.

Extensive travel, whether by plane, train, bus, or car, can increase the likelihood of developing blood clots.

“Standing and stretching the legs every two to four hours is advised for travelers at risk for deep vein thrombosis (DVT),”Dr. David Stone is a member the Society for Vascular Surgery. For healthy veins and arteries, Vascular surgeons encourage travel.

A blood clot could form in the veins of your leg during extended travel. If the clot is able to travel to the lungs, it can cause a pulmonary embolism.

According to statistics from the Centers for Disease Control and Prevention, between 300,000 and 600,000 Americans are killed each year by a blood clot in their lungs. The following are risk factors for the undiagnosed and preventable condition.

* Vein injury, including major surgery

* Slow blood flow from limited movement

* Increased estrogen levels from medications

* Chronic illnesses, such as heart disease, lung disease, cancer treatment or inflammatory bowel disease

* Family history of DVT

* Age

* Obesity

* Smoking

* High blood pressure

* A catheter in a central vein

* An inherited clotting disorder

Nearly anyone can be affected. David Bloom, a 39 year-old NBC News reporter, died in 2003 from a blood clot following weeks of travel around Baghdad with a cramped military vehicle.

“Whenever traveling in confined places, persons at risk of developing DVT should raise and lower their heels and toes and tighten and release their leg muscles,”Dr. Stone. “This helps to promote blood flow to the legs. Also, drink plenty of water, and wear loose-fitting clothes.”

As preventive measures against DVT, Vascular surgeons recommend regular exercise and a healthy weight. DVT can also be detected using ultrasound.

It is important to detect DVT early as half of DVT victims do not experience warning signs.

DVT can often be treated with anticoagulant medication. For more information on vascular health, visit VascularWeb.org (the Society for Vascular Surgery website).