Vice President Dick Cheney went to George Washington University Hospital Tuesday morning after experiencing discomfort in his left lower leg, where a blood clot was discovered a few weeks ago.

After consulting with his doctors, Cheney was asked to return to the hospital for repeat ultrasound imaging of the deep venous thrombosis, or clot, in that leg, said spokeswoman Megan McGinn

"The ultrasound revealed no extension or complication of the clot," she said. "His blood thinning medication was found to be therapeutic. These results are expected and reassuring, and the current course of treatment will continue."

Cheney returned to the White House to resume his normal schedule, she said.

Just over two weeks ago, doctors discovered a blood clot in the vice president's leg. They said at the time that he likely would have to be treated with blood-thinning medication for several months.

Spokeswoman Lee Anne McBride said at the time that the 66-year-old had visited his doctor's office on March 5 after feeling minor discomfort in his calf. An ultrasound showed the blood clot — called a deep venous thrombosis — in his left lower leg.

Blood clots that form deep in the legs can become killers if they break off and float into the lungs. This is called a pulmonary embolism. Deep vein thrombosis strikes an estimated 2 million Americans each year, killing 60,000.

Many people who suffer DVT do so after spending long periods without moving, such as passengers on long-haul airline flights. Cheney had just spent about 65 hours on a plane on a nine-day, round-the-world trip.

Cheney has had had a host of heart-related problems over the years.

He had six hours of surgery on his legs in 2005 to repair a kind of aneurysm, a ballooning weak spot in an artery that can burst if left untreated. He has had four heart attacks, quadruple bypass surgery, two artery-clearing angioplasties and an operation to implant a special pacemaker in his chest.