Varicose veins are a risk factor for developing a blood clot, specifically in the superficial system. It is one that occurs within the varicose vein known as a superficial venous thrombosis (SVT). More than 60% of patients who present with SVTs have varicose veins. That is an alarming number.
There is also a possibility of developing a deep vein thrombosis within the deep veins which is more dangerous and unfortunately can occur together with a superficial vein thrombosis between 6 to 40% of the time.
If you feel any pain, hardening of the varicose veins or swelling, you will need to get it checked out by your health provider especially to rule out a deep vein thrombosis.