It was a shock to 30-year-old swim coach Jill Greenleaf - a second blood clot within five years. She already knew the symptoms.
"One leg was swollen, warm, hot, painful to walk on," Greenleaf said.
An ultrasound confirmed Greenleaf’s blood clot was from her ankle to her hip. Blood clots can be fatal.
"The clot fragment or the whole clot can break free from the leg and travel through the body, through the lung and cause pulmonary embolism," Dr. Stephen Dempsey, interventional cardiologist said.
Other complications can be damage from chronic blockage.
"You will at least have a forty percent chance of developing chronic pain, swelling, discoloration," Dempsey said.
Other risk factors include smoking, malignant cancers, birth control pills and inactivity for long periods of time.
Restoring venous circulation can be done with medications and sometimes a surgical procedure called a thrombectomy, where the clot is sucked out.
"If we do demonstrate a large blood clot, we place a device in the vein and it allows us to do two things. It allows us to administer a blood thinning medication, or a blot clot busting medication, which dissolves the clot. And secondly, it allows us to disrupt the clot mechanically and suck the clot out of the vein," Dr. Dempsey explained.
For people who have had one blood clot, the risk for another one is greater.