There are three categories of causes of thrombosis: damage to the blood vessel (catheter or surgery) , slowed blood flow (immobility), and/or thrombophilia (if the blood itself is more likely to clot).

Over 11-inches of thrombic material removed from patient’s pulmonary artery – the thrombus originated in the lower extremities before migrating to the heart, where it formed a perfect cast of the artery.