Behavior of venous thrombi: historical observations.

Charles White in 1784 first demonstrated that milk leg was not caused by retained milk or lochia but rather by obstructing clots in the veins. In 1847, Virchow observed that venous thrombi often migrated to the lungs. Workers since then have found that, in general, thrombi in veins and in pulmonary arteries tend to form large recanalizing channels, accompanied by the destruction of any valves that are present, but that those in arteries form only small "arteries of organization." On the other hand, observers have reported capricious instances of opposite behavior. Furthermore, fresh thrombi and emboli in both systems occasionally disappear in the early period after formation or lodgement. It is urged that we use the full potential of modern diagnostic and monitoring methods to procure more data on the details of intravascular clot behavior.