The Fate of a Thrombus

Key points

• • A thrombus is a solid mass formed from blood inside a vessel during life, and once formed it can follow several different fates.
• • It may dissolve and disappear (resolution) if the body's clot-dissolving system breaks it down, which is likeliest when the thrombus is small and fresh.
• • It may become organised, as fibrous tissue and new vessels grow into it, and it can be re-canalised so that some blood flow is restored through it.
• • It may grow larger (propagation) by adding more clot, which can extend the blockage further along the vessel.
• • It may break off as an embolus that travels in the blood and lodges in a distant vessel, for example causing a pulmonary embolism from a leg vein clot.
• • Separately, a thrombus may become infected and softened; and although an infarct is a consequence of arterial blockage rather than a fate of the clot itself, an arterial thrombus that blocks flow starves the tissue beyond.