How could you tell if you have a blood clot in your thigh?

Only way to: Know for sure is to get a test called venous duplex ultrasound. Your doctor will need to order it. If there is a clot in the femoral vein, you are at risk for pulmonary embolism, which can be fatal. Time to see a doctor now.

Swelling and pain: While these are not specific, swelling and pain of the thigh or of the calf can be signs and symptoms of deep vein clots of the thighs. Blood clots of the arteries in the thighs would cause a cold, painful, and numb foot and calf. The only way to know for sure is to go to the er or see a vascular surgeon who can do an ultrasound of the blood vessels to see clot.