How did Rudolf Virchow explain the formation of thrombosis?

Rudolf Virchow significantly advanced medical science by disproving the prevailing 19th-century belief that phlebitis (inflammation of a vein) was the primary cause of most diseases.1

Instead, he demonstrated that the masses found within blood vessels were the result of a process he termed thrombosis. Virchow further explained that portions of these clots, or thrombi, could become detached and travel through the circulation to form an embolus. This embolus could then become trapped in a narrower vessel, causing serious lesions in the surrounding tissues.1

While modern medicine identifies various factors in clot formation—such as vessel injury, altered blood flow, and changes in blood coagulability—Virchow’s work was foundational in shifting the understanding of these vascular events away from simple inflammation toward a more precise pathological process.21