Deep Vein Thrombosis (DVT)

(WUSA) -- Seventeen year old Margaret Smith and her family have made many trips to Shady Grove Adventist Hospital in Rockville over the past few months.

Margaret's medical odyssey began in January, when the high school junior from North Potomac, Maryland, sat through a four-hour college ACT practice exam.

Margaret says it was difficult to sit still, as she felt building pain in her left leg and back.

Margaret says, "I wasn't concentrating at all... just wondering when the break would be so I could stand up."

She went home and told her parents about the pain. By the next morning, the family decided to take her to the emergency department at Shady Grove Adventist Hospital.

Eventually, tests would reveal a lengthy clot down the major vein in Margaret's left leg. This is what's called deep vein thrombosis, or DVT.

If a piece of that clot were to break off and travel back up to the teenager's lungs, it could cause a potentially fatal blockage of blood flow, a pulmonary embolism.

Her mother Barbara Smith says, "I was shocked and in disbelief, because Margaret is a fairly healthy young lady."

Dr. Richard Silva is the vascular surgeon who treated Margaret. He says this clot was more than a foot in length by the time it was discovered.

Dr. Silva says, "It really went from her belly all the way down her leg."

Dr. Silva says standard treatment involves trying to dissolve the clot with blood thinners. But that can leave the leg painful and swollen.

He opted for a relatively new technique, venous thrombectomy. It is performed while the patient is sedated, but still awake, in a catheterization lab.

Dr. Silva used a sterile sheath, or tube, to thread up the vein from behind Margaret's knee. Once the sheath was past the clot, the surgical team deployed a mesh filter to catch any pieces of the clot that might break free. Then the clot was dissolved with medication and sucked out before the small incision was closed. The filter was removed during a follow-up procedure a few weeks later. Margaret has made a full recovery, and hopes to resume playing sports soon.

Deep vein thrombosis, or DVT, is rare in people as young as Margaret. But the student athlete had been "kneed" in the groin area during a soccer game last fall. Doctors think that may have started the clot formation.

Trauma, surgery, and sitting or lying still for extended periods of time are all risk factors for DVT.

The key symptoms are pain, tenderness and swelling in the leg.

To avoid deep vein thrombosis, follow this advice from the National Heart Lung and Blood Institute:

During longer trips, especially those over 4 hours:

Walk up and down the aisles of the bus, train, or airplane. If traveling by car, stop about every hour and walk around.

Move your legs and flex and stretch your feet to encourage blood flow in your calves.

Wear loose and comfortable clothing.

Drink plenty of fluids and avoid alcohol.