PHILADELPHIA (WPVI) -- Jessica Winn was just weeks into motherhood when things went wrong.
"I was sitting on the couch feeding him, and I looked down and noticed that my leg was swollen," recalls Jessica.
She was initially told she had a superficial blood clot and sent her home. But within hours, she was back at the hospital.
"The clot started up here and went through a lot of these veins," she says, pointing to her leg.
A hospital at her home in Dallas, Texas, said the massive clot couldn't be removed.
Jessica was put on blood thinners, and told: "No more running, no more skiing, no more hiking, no playing around with my newborn baby," she notes.
Then, a relative connected her with Dr. Deepak Sudheendra at Penn Medicine. He discovered Jessica had May-Thurner Syndrome.
It occurs when an artery in the pelvis lays on top of, and compresses a major vein.
The blood there slows down, and a clot can form in the leg. Some doctors say the condition is rare.
Dr. Sudheendra doesn't agree.
"May-Thurner syndrome probably is present in what we think may be 25% of the population," he says.
Dr. Sudheendra says for most people, it never causes symptoms. But weight gain, or inactivity could raise the risk of trouble.
And so does pregnancy. "If you have a growing baby there, there's less room, and more compression," he notes.
Dr. Sudheendra broke up the clot with a device that sprays it with powerful drugs, then vacuums it out.
He also put a stent into the vein to keep it open.
Jessica was on blood thinners for a while, but now just takes a baby aspirin.
And she's cleared for all her activities.
"I'm running again and walking again and doing anything and everything," she says with a broad smile.
But Jessica does wish she had been more aware of the risk for clots.
She urges any woman who is pregnant, or any new mom with swelling in her leg to get it checked out right away.