Thrombosis is a medical condition that occurs when a blood clot forms in a vein or artery. It can lead to serious health problems such as stroke, pulmonary embolism, heart attack, or deep vein thrombosis. Risk factors for thrombosis include family history, age, certain medical conditions such as cancer, being overweight, smoking, and taking certain medications. Treatment options include anticoagulants, thrombolytic therapy, and mechanical means such as catheter-directed thrombolysis. Surgery may also be necessary in certain cases.