The movie "The 33" details the lives of 33 Chilean miners who were exploring a vein of copper deep in the earth when a cave-in trapped them in the narrow shaft. If you want to understand what deep vein thrombosis is, the comparison is a pretty good one.

For miners, the deeper they dig, the tougher it is to get them out if something bad happens.

For those with a blood clot (thrombus), if it's lodged in a deep vein of your leg, the more potentially life-threatening the situation becomes. The clot can travel from those deep veins back to your heart and lodge in your lungs, where it causes sudden death about 25 percent of the time.

Five years ago, the National Institutes of Health estimated deep vein thrombosis (DVT) affected 300,000 to 600,000 folks in the U.S. annually. Today the Centers for Disease Control and Prevention believes the number could be as high as 900,000.

The biggest risk factors for DVT include a previous blood clot (take a blood thinner, if prescribed, and two 82 mg aspirins daily if your doc agrees), obesity (lose weight by banishing added sugars and syrups, processed foods, trans, and sat fats), immobility (stand up frequently and walk as much as possible) and surgery (that's why you wear calf massagers post-op).

The most obvious symptoms of DVT are swelling and reddish-purple discoloration in a lower extremity. If a clot is suspected, screening can be done using ultrasound, venography, and MRI.

If a doctor finds a DVT, treatment is typically anticoagulation therapy. And great news: All 33 miners survived.