OKLAHOMA CITY -- Melanie Bloom was used to worrying about her husband while he was at work.

David Bloom, a journalist with NBC News, had covered dangerous assignments all over the world. But little did Melanie Bloom know that when he was imbedded with U.S. soldiers in Iraq in 2003, the danger wouldn't be from insurgents.

"(It was) more shocking to learn it was something in his own body," Bloom said of her husband's sudden death.

David Bloom died from deep vein thrombosis, an abnormal clotting of the blood in a deep vein, commonly in the leg or pelvis. A blood clot in his leg broke off and traveled through the bloodstream and into his lungs, a condition known as pulmonary embolism.

His wife had never heard of the disorder that killed her husband, but since his death, Melanie Bloom has become a spokesperson for the Coalition to Prevent DVT.

Bloom spoke Tuesday at the Public Health Grand Rounds at the University of Oklahoma Health Sciences Center in Oklahoma City. Her visit was part of the activities surrounding the month of June, which was named DVT Awareness Month in Oklahoma.

The problem of DVT and PE is widespread. Up to 1 million Americans suffer from DVT or PE every year. About 300,000 patients die as a result of PE.

"Unlike other diseases that we just can't prevent, we can actually do something about this," said Suman Rathbun, vascular specialist at the OU College of Medicine.

Blood thinners can be administered to prevent blood clots, but much of the prevention has to do with awareness, she said. It's important to recognize the risk factors, including taking birth control pills or hormone replacement therapy, obesity, family history of blood clots, prolonged travel or recent surgery.

Symptoms of DVT include pain, tenderness and swelling in the calf or thigh, which can be warm to the touch. But as many as half of all DVT cases produce minimal or no symptoms.

David Bloom had several of the risk factors, which created the "perfect storm" to bring about DVT, his wife said.

Bloom had a genetic predisposition to the disorder, but that wasn't discovered until after his death. Additionally, he was dehydrated in the desert and slept in cramped quarters with his knees tucked up against his chest.

About two days before he died, Bloom told his wife over the phone about leg pain.

His producer, who was from the United Kingdom, gave him the number of a hotline in the U.K. Bloom spoke with a doctor, but without seeing him in person the doctor said the leg pain could be any from any of a number of factors.

So Bloom shrugged off the pain. And his wife didn't think anything of it either.